ovs-vswitchd.conf.db(5)       Open vSwitch Manual      ovs-vswitchd.conf.db(5)



NAME
       ovs-vswitchd.conf.db - Open_vSwitch database schema

       A  database  with  this  schema  holds  the  configuration for one Open
       vSwitch daemon. The top-level  configuration  for  the  daemon  is  the
       Open_vSwitch  table,  which  must  have  exactly one record. Records in
       other tables are significant only when they can be reached directly  or
       indirectly  from the Open_vSwitch table. Records that are not reachable
       from the Open_vSwitch table are automatically deleted  from  the  data‐
       base, except for records in a few distinguished ``root set’’ tables.

   Common Columns
       Most  tables contain two special columns, named other_config and exter‐
       nal_ids. These columns have the same form and purpose each  place  that
       they appear, so we describe them here to save space later.

              other_config: map of string-string pairs
                     Key-value  pairs  for  configuring  rarely used features.
                     Supported keys, along with the forms taken by their  val‐
                     ues, are documented individually for each table.

                     A  few tables do not have other_config columns because no
                     key-value pairs have yet been defined for them.

              external_ids: map of string-string pairs
                     Key-value pairs for use by external frameworks that inte‐
                     grate  with  Open  vSwitch,  rather  than by Open vSwitch
                     itself. System integrators should  either  use  the  Open
                     vSwitch  development mailing list to coordinate on common
                     key-value definitions,  or  choose  key  names  that  are
                     likely to be unique. In some cases, where key-value pairs
                     have been defined that are likely to  be  widely  useful,
                     they are documented individually for each table.

TABLE SUMMARY
       The  following list summarizes the purpose of each of the tables in the
       Open_vSwitch database.  Each table is described in  more  detail  on  a
       later page.

       Table     Purpose
       Open_vSwitch
                 Open vSwitch configuration.
       Bridge    Bridge configuration.
       Port      Port configuration.
       Interface One physical network device in a Port.
       Flow_Table
                 OpenFlow table configuration
       QoS       Quality of Service configuration
       Queue     QoS output queue.
       Mirror    Port mirroring.
       Controller
                 OpenFlow controller configuration.
       Manager   OVSDB management connection.
       NetFlow   NetFlow configuration.
       Datapath  Datapath configuration.
       CT_Zone   CT_Zone configuration.
       CT_Timeout_Policy
                 CT_Timeout_Policy configuration.
       SSL       SSL configuration.
       sFlow     sFlow configuration.
       IPFIX     IPFIX configuration.
       Flow_Sample_Collector_Set
                 Flow_Sample_Collector_Set configuration.
       AutoAttach
                 AutoAttach configuration.

Open_vSwitch TABLE
       Configuration  for  an  Open  vSwitch daemon. There must be exactly one
       record in the Open_vSwitch table.

   Summary:
       Configuration:
         datapaths                   map of string-Datapath pairs
         bridges                     set of Bridges
         ssl                         optional SSL
         external_ids : system-id    optional string
         external_ids : xs-system-uuid
                                     optional string
         external_ids : hostname     optional string
         external_ids : rundir       optional string
         other_config : stats-update-interval
                                     optional string, containing  an  integer,
                                     at least 5,000
         other_config : flow-restore-wait
                                     optional string, either true or false
         other_config : flow-limit   optional  string,  containing an integer,
                                     at least 0
         other_config : max-idle     optional string, containing  an  integer,
                                     at least 500
         other_config : max-revalidator
                                     optional  string,  containing an integer,
                                     at least 100
         other_config : min-revalidate-pps
                                     optional string, containing  an  integer,
                                     at least 1
         other_config : hw-offload   optional string, either true or false
         other_config : tc-policy    optional string, one of none, skip_hw, or
                                     skip_sw
         other_config : dpdk-init    optional string, one of false,  true,  or
                                     try
         other_config : dpdk-lcore-mask
                                     optional  string,  containing an integer,
                                     at least 1
         other_config : pmd-cpu-mask
                                     optional string
         other_config : dpdk-alloc-mem
                                     optional string, containing  an  integer,
                                     at least 0
         other_config : dpdk-socket-mem
                                     optional string
         other_config : dpdk-socket-limit
                                     optional string
         other_config : dpdk-hugepage-dir
                                     optional string
         other_config : dpdk-extra   optional string
         other_config : vhost-sock-dir
                                     optional string
         other_config : vhost-iommu-support
                                     optional string, either true or false
         other_config : vhost-postcopy-support
                                     optional string, either true or false
         other_config : per-port-memory
                                     optional string, either true or false
         other_config : tx-flush-interval
                                     optional  string,  containing an integer,
                                     in range 0 to 1,000,000
         other_config : pmd-perf-metrics
                                     optional string, either true or false
         other_config : smc-enable   optional string, either true or false
         other_config : pmd-rxq-assign
                                     optional   string,   either   cycles   or
                                     roundrobin
         other_config : n-handler-threads
                                     optional  string,  containing an integer,
                                     at least 1
         other_config : n-revalidator-threads
                                     optional string, containing  an  integer,
                                     at least 1
         other_config : emc-insert-inv-prob
                                     optional  string,  containing an integer,
                                     in range 0 to 4,294,967,295
         other_config : vlan-limit   optional string, containing  an  integer,
                                     at least 0
         other_config : bundle-idle-timeout
                                     optional  string,  containing an integer,
                                     at least 1
         other_config : offload-rebalance
                                     optional string, either true or false
         other_config : pmd-auto-lb  optional string, either true or false
         other_config : pmd-auto-lb-rebal-interval
                                     optional string, containing  an  integer,
                                     in range 0 to 20,000
         other_config : pmd-auto-lb-load-threshold
                                     optional  string,  containing an integer,
                                     in range 0 to 100
         other_config : pmd-auto-lb-improvement-threshold
                                     optional string, containing  an  integer,
                                     in range 0 to 100
         other_config : userspace-tso-enable
                                     optional string, either true or false
       Status:
         next_cfg                    integer
         cur_cfg                     integer
         dpdk_initialized            boolean
         Statistics:
            other_config : enable-statistics
                                     optional string, either true or false
            statistics : cpu         optional  string,  containing an integer,
                                     at least 1
            statistics : load_average
                                     optional string
            statistics : memory      optional string
            statistics : process_NAME
                                     optional string
            statistics : file_systems
                                     optional string
       Version Reporting:
         ovs_version                 optional string
         db_version                  optional string
         system_type                 optional string
         system_version              optional string
         dpdk_version                optional string
       Capabilities:
         datapath_types              set of strings
         iface_types                 set of strings
       Database Configuration:
         manager_options             set of Managers
       IPsec:
         other_config : private_key  optional string
         other_config : certificate  optional string
         other_config : ca_cert      optional string
         Plaintext Tunnel Policy:
            other_config : ipsec_skb_mark
                                     optional string
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
     Configuration:

       datapaths: map of string-Datapath pairs
              Map of datapath types to datapaths. The datapath_type column  of
              the Bridge table is used as a key for this map. The value points
              to a row in the Datapath table.

       bridges: set of Bridges
              Set of bridges managed by the daemon.

       ssl: optional SSL
              SSL used globally by the daemon.

       external_ids : system-id: optional string
              A unique identifier for the Open vSwitch’s  physical  host.  The
              form  of  the  identifier  depends on the type of the host. On a
              Citrix XenServer,  this  will  likely  be  the  same  as  exter‐
              nal_ids:xs-system-uuid.

       external_ids : xs-system-uuid: optional string
              The Citrix XenServer universally unique identifier for the phys‐
              ical host as displayed by xe host-list.

       external_ids : hostname: optional string
              The hostname for the host running Open vSwitch. This is a  fully
              qualified domain name since version 2.6.2.

       external_ids : rundir: optional string
              In  Open vSwitch 2.8 and later, the run directory of the running
              Open vSwitch daemon. This directory is used  for  runtime  state
              such  as control and management sockets. The value of other_con‐
              fig:vhost-sock-dir is relative to this directory.

       other_config : stats-update-interval: optional  string,  containing  an
       integer, at least 5,000
              Interval  for  updating statistics to the database, in millisec‐
              onds. This option will affect the update of the statistics  col‐
              umn in the following tables: Port, Interface , Mirror.

              Default value is 5000 ms.

              Getting statistics more frequently can be achieved via OpenFlow.

       other_config : flow-restore-wait: optional string, either true or false
              When  ovs-vswitchd  starts  up,  it  has an empty flow table and
              therefore it handles all arriving packets in its default fashion
              according to its configuration, by dropping them or sending them
              to an OpenFlow controller or  switching  them  as  a  standalone
              switch.  This  behavior  is  ordinarily  desirable.  However, if
              ovs-vswitchd is restarting as part of  a  ``hot-upgrade,’’  then
              this  leads to a relatively long period during which packets are
              mishandled.

              This option allows for  improvement.  When  ovs-vswitchd  starts
              with  this  value  set  as true, it will neither flush or expire
              previously set datapath flows nor will it send and  receive  any
              packets to or from the datapath. When this value is later set to
              false, ovs-vswitchd will start receiving packets from the  data‐
              path and re-setup the flows.

              Additionally,  ovs-vswitchd is prevented from connecting to con‐
              trollers when this value is set  to  true.  This  prevents  con‐
              trollers  from making changes to the flow table in the middle of
              flow restoration, which could result in undesirable intermediate
              states.  Once  this  value has been set to false and the desired
              flow state has been  restored,  ovs-vswitchd  will  be  able  to
              reconnect  to controllers and process any new flow table modifi‐
              cations.

              Thus, with this option,  the  procedure  for  a  hot-upgrade  of
              ovs-vswitchd becomes roughly the following:

              1.  Stop ovs-vswitchd.

              2.  Set other_config:flow-restore-wait to true.

              3.  Start ovs-vswitchd.

              4.  Use  ovs-ofctl  (or  some other program, such as an OpenFlow
                  controller) to  restore  the  OpenFlow  flow  table  to  the
                  desired state.

              5.  Set  other_config:flow-restore-wait  to  false (or remove it
                  entirely from the database).

              The ovs-ctl’s ``restart’’  and  ``force-reload-kmod’’  functions
              use the above config option during hot upgrades.

       other_config  :  flow-limit: optional string, containing an integer, at
       least 0
              The maximum number of flows allowed in the datapath flow  table.
              Internally  OVS  will  choose  a flow limit which will likely be
              lower than this number, based on real time  network  conditions.
              Tweaking  this value is discouraged unless you know exactly what
              you’re doing.

              The default is 200000.

       other_config : max-idle: optional string,  containing  an  integer,  at
       least 500
              The  maximum  time (in ms) that idle flows will remain cached in
              the datapath. Internally OVS will check the validity and  activ‐
              ity  for  datapath  flows regularly and may expire flows quicker
              than this number, based on real time network conditions.  Tweak‐
              ing  this  value  is  discouraged  unless  you know exactly what
              you’re doing.

              The default is 10000.

       other_config : max-revalidator: optional string, containing an integer,
       at least 100
              The  maximum  time  (in  ms)  that revalidator threads will wait
              before executing flow revalidation. Note that  this  is  maximum
              allowed value. Actual timeout used by OVS is minimum of max-idle
              and max-revalidator values. Tweaking this value  is  discouraged
              unless you know exactly what you’re doing.

              The default is 500.

       other_config : min-revalidate-pps: optional string, containing an inte‐
       ger, at least 1
              Set minimum pps that flow must have in order to  be  revalidated
              when  revalidation duration exceeds half of max-revalidator con‐
              fig variable.

              The default is 5.

       other_config : hw-offload: optional string, either true or false
              Set this value to true to enable netdev flow offload.

              The  default  value  is  false.  Changing  this  value  requires
              restarting the daemon

              Currently  Open  vSwitch  supports  hardware offloading on Linux
              systems. On other systems, this value is ignored. This function‐
              ality  is considered ’experimental’. Depending on which OpenFlow
              matches and actions are  configured,  which  kernel  version  is
              used,  and  what  hardware is available, Open vSwitch may not be
              able to offload functionality to hardware.

              In  order  to   dump   HW   offloaded   flows   use   ovs-appctl
              dpctl/dump-flows,  ovs-dpctl doesn’t support this functionality.
              See ovs-vswitchd(8) for details.

       other_config : tc-policy: optional string, one  of  none,  skip_hw,  or
       skip_sw
              Specified the policy used with HW offloading. Options:

              none   Add software rule and offload rule to HW.

              skip_sw
                     Offload rule to HW only.

              skip_hw
                     Add software rule without offloading rule to HW.

              This is only relevant if other_config:hw-offload is enabled.

              The default value is none.

       other_config : dpdk-init: optional string, one of false, true, or try
              Set this value to true or try to enable runtime support for DPDK
              ports. The vswitch must have compile-time support  for  DPDK  as
              well.

              A  value of true will cause the ovs-vswitchd process to abort if
              DPDK cannot be initialized. A value of try will allow  the  ovs-
              vswitchd process to continue running even if DPDK cannot be ini‐
              tialized.

              The  default  value  is  false.  Changing  this  value  requires
              restarting the daemon

              If this value is false at startup, any dpdk ports which are con‐
              figured in the bridge will fail due to memory errors.

       other_config : dpdk-lcore-mask: optional string, containing an integer,
       at least 1
              Specifies  the  CPU  cores  where  dpdk  lcore threads should be
              spawned. The DPDK lcore threads are used for DPDK library tasks,
              such as library internal message processing, logging, etc. Value
              should be in the form of a hex string (so  ’0x123’)  similar  to
              the ’taskset’ mask input.

              The  lowest  order  bit corresponds to the first CPU core. A set
              bit means the corresponding  core  is  available  and  an  lcore
              thread  will  be created and pinned to it. If the input does not
              cover all cores, those uncovered cores are considered not set.

              For performance reasons, it is best to set this to a single core
              on the system, rather than allow lcore threads to float.

              If  not  specified, the value will be determined by choosing the
              lowest CPU core from initial cpu affinity list.  Otherwise,  the
              value will be passed directly to the DPDK library.

       other_config : pmd-cpu-mask: optional string
              Specifies  CPU  mask  for  setting the cpu affinity of PMD (Poll
              Mode Driver) threads. Value should be in the form of hex string,
              similar  to  the  dpdk  EAL  ’-c  COREMASK’  option input or the
              ’taskset’ mask input.

              The lowest order bit corresponds to the first CPU  core.  A  set
              bit  means  the corresponding core is available and a pmd thread
              will be created and pinned to it. If the input  does  not  cover
              all cores, those uncovered cores are considered not set.

              If  not  specified, one pmd thread will be created for each numa
              node and pinned to any  available  core  on  the  numa  node  by
              default.

       other_config  : dpdk-alloc-mem: optional string, containing an integer,
       at least 0
              Specifies the amount of memory to preallocate from the  hugepage
              pool,  regardless of socket. It is recommended that dpdk-socket-
              mem is used instead.

       other_config : dpdk-socket-mem: optional string
              Specifies the amount of memory to preallocate from the  hugepage
              pool, on a per-socket basis.

              The specifier is a comma-separated string, in ascending order of
              CPU socket. E.g. On a four socket system 1024,0,2048  would  set
              socket  0  to  preallocate  1024MB, socket 1 to preallocate 0MB,
              socket 2 to preallocate 2048MB and socket 3 (no value given)  to
              preallocate 0MB.

              If  dpdk-socket-mem  and dpdk-alloc-mem are not specified, dpdk-
              socket-mem will be used and the default value is 1024  for  each
              numa  node.  If dpdk-socket-mem and dpdk-alloc-mem are specified
              at same time, dpdk-socket-mem will be used as default.  Changing
              this value requires restarting the daemon.

       other_config : dpdk-socket-limit: optional string
              Limits  the  maximum  amount of memory that can be used from the
              hugepage pool, on a per-socket basis.

              The specifier is a comma-separated list  of  memory  limits  per
              socket. 0 will disable the limit for a particular socket.

              If  not specified, OVS will configure limits equal to the amount
              of preallocated memory specified by other_config:dpdk-socket-mem
              or --socket-mem in other_config:dpdk-extra. If none of the above
              options specified or --legacy-mem provided in other_config:dpdk-
              extra,  limits will not be applied. Changing this value requires
              restarting the daemon.

       other_config : dpdk-hugepage-dir: optional string
              Specifies the path to the hugetlbfs mount point.

              If not specified, this will  be  guessed  by  the  DPDK  library
              (default   is  /dev/hugepages).  Changing  this  value  requires
              restarting the daemon.

       other_config : dpdk-extra: optional string
              Specifies additional eal command line arguments for DPDK.

              The default is empty. Changing this  value  requires  restarting
              the daemon

       other_config : vhost-sock-dir: optional string
              Specifies a relative path from external_ids:rundir to the vhost-
              user unix domain socket files. If this value is unset, the sock‐
              ets are put directly in external_ids:rundir.

              Changing this value requires restarting the daemon.

       other_config  :  vhost-iommu-support:  optional  string, either true or
       false
              vHost IOMMU is a security feature,  which  restricts  the  vhost
              memory  that  a virtio device may access. vHost IOMMU support is
              disabled by default, due to a bug in QEMU implementations of the
              vhost REPLY_ACK protocol, (on which vHost IOMMU relies) prior to
              v2.9.1. Setting this value to true enables vHost  IOMMU  support
              for  vHost  User  Client  ports  in OvS-DPDK, starting from DPDK
              v17.11.

              Changing this value requires restarting the daemon.

       other_config : vhost-postcopy-support: optional string, either true  or
       false
              vHost  post-copy is a feature which allows switching live migra‐
              tion of VM attached to  dpdkvhostuserclient  port  to  post-copy
              mode if default pre-copy migration can not be converged or takes
              too long to converge. Setting this value to true  enables  vHost
              post-copy  support  for all dpdkvhostuserclient ports. Available
              starting from DPDK v18.11 and QEMU 2.12.

              Changing this value requires restarting the daemon.

       other_config : per-port-memory: optional string, either true or false
              By default OVS DPDK uses a shared memory model  wherein  devices
              that have the same MTU and socket values can share the same mem‐
              pool. Setting this value to true  changes  this  behaviour.  Per
              port memory allow DPDK devices to use private memory per device.
              This can provide greater transparency as  regards  memory  usage
              but potentially at the cost of greater memory requirements.

              Changing  this value requires restarting the daemon if dpdk-init
              has already been set to true.

       other_config : tx-flush-interval: optional string, containing an  inte‐
       ger, in range 0 to 1,000,000
              Specifies  the  time  in  microseconds that a packet can wait in
              output batch for sending i.e. amount of  time  that  packet  can
              spend  in an intermediate output queue before sending to netdev.
              This option can be used to configure balance between  throughput
              and  latency. Lower values decreases latency while higher values
              may be useful to achieve higher performance.

              Defaults to 0 i.e. instant packet sending (latency optimized).

       other_config : pmd-perf-metrics: optional string, either true or false
              Enables recording of detailed PMD performance metrics for analy‐
              sis  and trouble-shooting. This can have a performance impact in
              the order of 1%.

              Defaults to false but can be changed at any time.

       other_config : smc-enable: optional string, either true or false
              Signature match cache or SMC is a cache between EMC and megaflow
              cache. It does not store the full key of the flow, so it is more
              memory efficient comparing to EMC cache. SMC is especially  use‐
              ful when flow count is larger than EMC capacity.

              Defaults to false but can be changed at any time.

       other_config  :  pmd-rxq-assign:  optional  string,  either  cycles  or
       roundrobin
              Specifies how RX queues will be automatically  assigned  to  CPU
              cores. Options:

              cycles Rxqs  will  be  sorted  by  order  of measured processing
                     cycles before being assigned to CPU cores.

              roundrobin
                     Rxqs will be round-robined across CPU cores.

              The default value is cycles.

              Changing this value will affect an  automatic  re-assignment  of
              Rxqs to CPUs. Note: Rxqs mapped to CPU cores with pmd-rxq-affin‐
              ity are unaffected.

       other_config : n-handler-threads: optional string, containing an  inte‐
       ger, at least 1
              Specifies  the  number  of threads for software datapaths to use
              for handling new flows. The default the  number  of  online  CPU
              cores minus the number of revalidators.

              This  configuration  is  per datapath. If you have more than one
              software datapath (e.g. some  system  bridges  and  some  netdev
              bridges),  then the total number of threads is n-handler-threads
              times the number of software datapaths.

       other_config : n-revalidator-threads: optional  string,  containing  an
       integer, at least 1
              Specifies  the  number  of threads for software datapaths to use
              for revalidating flows in the datapath. Typically,  there  is  a
              direct  correlation  between  the number of revalidator threads,
              and the number of flows allowed in the datapath. The default  is
              the  number  of  cpu  cores  divided by four plus one. If n-han‐
              dler-threads is set, the default changes to the  number  of  cpu
              cores minus the number of handler threads.

              This  configuration  is  per datapath. If you have more than one
              software datapath (e.g. some  system  bridges  and  some  netdev
              bridges),  then the total number of threads is n-handler-threads
              times the number of software datapaths.

       other_config :  emc-insert-inv-prob:  optional  string,  containing  an
       integer, in range 0 to 4,294,967,295
              Specifies  the  inverse probability (1/emc-insert-inv-prob) of a
              flow being inserted into the Exact Match Cache (EMC). On average
              one  in every emc-insert-inv-prob packets that generate a unique
              flow will cause an insertion into the EMC. A  value  of  1  will
              result  in  an  insertion  for every flow (1/1 = 100%) whereas a
              value of zero will result in no insertions and essentially  dis‐
              able the EMC.

              Defaults  to  100 ie. there is (1/100 =) 1% chance of EMC inser‐
              tion.

       other_config : vlan-limit: optional string, containing an  integer,  at
       least 0
              Limits  the  number  of  VLAN headers that can be matched to the
              specified number. Further VLAN headers will be treated  as  pay‐
              load, e.g. a packet with more 802.1q headers will match Ethernet
              type 0x8100.

              Open vSwitch userspace currently supports at most 2  VLANs,  and
              each  datapath  has  its own limit. If vlan-limit is nonzero, it
              acts as a further limit.

              If this value is absent, the default is currently 1. This  main‐
              tains backward compatibility with controllers that were designed
              for use with Open vSwitch versions earlier than 2.8, which  only
              supported one VLAN.

       other_config  :  bundle-idle-timeout:  optional  string,  containing an
       integer, at least 1
              The maximum time (in seconds) that idle bundles will wait to  be
              expired since it was either opened, modified or closed.

              OpenFlow  specification  mandates the timeout to be at least one
              second. The default is 10 seconds.

       other_config : offload-rebalance: optional string, either true or false
              Configures HW offload rebalancing, that  allows  to  dynamically
              offload  and  un-offload flows while an offload-device is out of
              resources (OOR). This policy allows flows  to  be  selected  for
              offloading based on the packets-per-second (pps) rate of flows.

              Set this value to true to enable this option.

              The  default  value  is  false.  Changing  this  value  requires
              restarting the daemon.

              This is only relevant if HW offloading is enabled  (hw-offload).
              When  this policy is enabled, it also requires ’tc-policy’ to be
              set to ’skip_sw’.

       other_config : pmd-auto-lb: optional string, either true or false
              Configures PMD Auto Load Balancing that allows automatic assign‐
              ment  of  RX queues to PMDs if any of PMDs is overloaded (i.e. a
              processing cycles > other_config:pmd-auto-lb-load-threshold).

              It uses current scheme of cycle based assignment  of  RX  queues
              that are not statically pinned to PMDs.

              The default value is false.

              Set  this  value  to true to enable this option. It is currently
              disabled by default and an experimental feature.

              This only comes in effect if cycle based assignment  is  enabled
              and  there  are  more  than one non-isolated PMDs present and at
              least one of it polls more than one queue.

       other_config : pmd-auto-lb-rebal-interval: optional string,  containing
       an integer, in range 0 to 20,000
              The  minimum  time (in minutes) 2 consecutive PMD Auto Load Bal‐
              ancing iterations.

              The defaul value is 1 min. If configured to 0 then it  would  be
              converted to default value i.e. 1 min

              This  option can be configured to avoid frequent trigger of auto
              load balancing of PMDs. For e.g. set the  value  (in  min)  such
              that it occurs once in few hours or a day or a week.

       other_config  : pmd-auto-lb-load-threshold: optional string, containing
       an integer, in range 0 to 100
              Specifies the minimum PMD  thread  load  threshold  (%  of  used
              cycles)  of  any  non-isolated  PMD threads when a PMD Auto Load
              Balance may be triggered.

              The default value is 95%.

       other_config : pmd-auto-lb-improvement-threshold: optional string, con‐
       taining an integer, in range 0 to 100
              Specifies  the minimum evaluated % improvement in load distribu‐
              tion across the non-isolated PMD threads that will allow  a  PMD
              Auto Load Balance to occur.

              Note, setting this parameter to 0 will always allow an auto load
              balance to occur regardless of estimated improvement or not.

              The default value is 25%.

       other_config : userspace-tso-enable: optional string,  either  true  or
       false
              Set  this value to true to enable userspace support for TCP Seg‐
              mentation Offloading (TSO). When it is enabled,  the  interfaces
              can  provide  an  oversized  TCP segment to the datapath and the
              datapath will offload the TCP segmentation and checksum calcula‐
              tion to the interfaces when necessary.

              The  default  value  is  false.  Changing  this  value  requires
              restarting the daemon.

              The feature only works if Open vSwitch is built with  DPDK  sup‐
              port.

              The feature is considered experimental.

     Status:

       next_cfg: integer
              Sequence  number for client to increment. When a client modifies
              any part of the database configuration and wishes  to  wait  for
              Open  vSwitch  to  finish applying the changes, it may increment
              this sequence number.

       cur_cfg: integer
              Sequence number that Open vSwitch sets to the current  value  of
              next_cfg  after  it  finishes  applying  a  set of configuration
              changes.

       dpdk_initialized: boolean
              True if other_config:dpdk-init is  set  to  true  and  the  DPDK
              library is successfully initialized.

     Statistics:

       The  statistics  column contains key-value pairs that report statistics
       about a system running an Open vSwitch. These are updated  periodically
       (currently, every 5 seconds). Key-value pairs that cannot be determined
       or that do not apply to a platform are omitted.

       other_config : enable-statistics: optional string, either true or false
              Statistics are disabled by default to avoid overhead in the com‐
              mon case when statistics gathering is not useful. Set this value
              to true to enable populating the statistics column or  to  false
              to explicitly disable it.

       statistics : cpu: optional string, containing an integer, at least 1
              Number of CPU processors, threads, or cores currently online and
              available to the operating system on which Open vSwitch is  run‐
              ning, as an integer. This may be less than the number installed,
              if some are not online or if they are not available to the oper‐
              ating system.

              Open  vSwitch userspace processes are not multithreaded, but the
              Linux kernel-based datapath is.

       statistics : load_average: optional string
              A comma-separated list of three floating-point  numbers,  repre‐
              senting  the system load average over the last 1, 5, and 15 min‐
              utes, respectively.

       statistics : memory: optional string
              A comma-separated list of integers, each of which  represents  a
              quantity  of  memory  in  kilobytes that describes the operating
              system on which Open vSwitch is running.  In  respective  order,
              these values are:

              1.  Total amount of RAM allocated to the OS.

              2.  RAM allocated to the OS that is in use.

              3.  RAM  that  can be flushed out to disk or otherwise discarded
                  if that space is needed for another purpose. This number  is
                  necessarily less than or equal to the previous value.

              4.  Total disk space allocated for swap.

              5.  Swap space currently in use.

              On Linux, all five values can be determined and are included. On
              other operating systems, only the first two values can be deter‐
              mined, so the list will only have two values.

       statistics : process_NAME: optional string
              One  such  key-value pair, with NAME replaced by a process name,
              will exist for each running Open vSwitch  daemon  process,  with
              name  replaced by the daemon’s name (e.g. process_ovs-vswitchd).
              The value is a comma-separated list of  integers.  The  integers
              represent  the  following, with memory measured in kilobytes and
              durations in milliseconds:

              1.  The process’s virtual memory size.

              2.  The process’s resident set size.

              3.  The amount of user and  system  CPU  time  consumed  by  the
                  process.

              4.  The  number  of  times that the process has crashed and been
                  automatically restarted by the monitor.

              5.  The duration since the process was started.

              6.  The duration for which the process has been running.

              The interpretation of some of these values  depends  on  whether
              the  process was started with the --monitor. If it was not, then
              the crash count will always be 0  and  the  two  durations  will
              always be the same. If --monitor was given, then the crash count
              may be positive; if it is, the latter duration is the amount  of
              time since the most recent crash and restart.

              There will be one key-value pair for each file in Open vSwitch’s
              ``run directory’’ (usually /var/run/openvswitch) whose name ends
              in .pid, whose contents are a process ID, and which is locked by
              a running process. The name is taken from the pidfile’s name.

              Currently Open vSwitch is only able to obtain all of  the  above
              detail  on  Linux  systems. On other systems, the same key-value
              pairs will be present but the values will always  be  the  empty
              string.

       statistics : file_systems: optional string
              A  space-separated  list  of information on local, writable file
              systems. Each item in the list describes  one  file  system  and
              consists in turn of a comma-separated list of the following:

              1.  Mount point, e.g. / or /var/log. Any spaces or commas in the
                  mount point are replaced by underscores.

              2.  Total size, in kilobytes, as an integer.

              3.  Amount of storage in use, in kilobytes, as an integer.

              This key-value pair is omitted if there are no  local,  writable
              file  systems or if Open vSwitch cannot obtain the needed infor‐
              mation.

     Version Reporting:

       These columns report the types and versions of the hardware  and  soft‐
       ware running Open vSwitch. We recommend in general that software should
       test whether specific features are supported instead of relying on ver‐
       sion  number  checks. These values are primarily intended for reporting
       to human administrators.

       ovs_version: optional string
              The Open vSwitch version number, e.g. 1.1.0.

       db_version: optional string
              The database schema  version  number,  e.g.  1.2.3.  See  ovsdb-
              tool(1) for an explanation of the numbering scheme.

              The  schema  version  is  part of the database schema, so it can
              also be retrieved by fetching the schema using the Open  vSwitch
              database protocol.

       system_type: optional string
              An  identifier  for  the  type  of  system  on top of which Open
              vSwitch runs, e.g. XenServer or KVM.

              System integrators are responsible for choosing and  setting  an
              appropriate value for this column.

       system_version: optional string
              The  version  of  the  system  identified  by  system_type, e.g.
              5.6.100-39265p on XenServer 5.6.100 build 39265.

              System integrators are responsible for choosing and  setting  an
              appropriate value for this column.

       dpdk_version: optional string
              The version of the linked DPDK library.

     Capabilities:

       These columns report capabilities of the Open vSwitch instance.

       datapath_types: set of strings
              This column reports the different dpifs registered with the sys‐
              tem. These are the values that this  instance  supports  in  the
              datapath_type column of the Bridge table.

       iface_types: set of strings
              This  column  reports  the different netdevs registered with the
              system. These are the values that this instance supports in  the
              type column of the Interface table.

     Database Configuration:

       These   columns   primarily   configure   the   Open  vSwitch  database
       (ovsdb-server), not the Open vSwitch switch (ovs-vswitchd).  The  OVSDB
       database also uses the ssl settings.

       The  Open vSwitch switch does read the database configuration to deter‐
       mine remote IP addresses to which in-band control should apply.

       manager_options: set of Managers
              Database clients to  which  the  Open  vSwitch  database  server
              should  connect or to which it should listen, along with options
              for how these connections should be configured. See the  Manager
              table for more information.

              For  this column to serve its purpose, ovsdb-server must be con‐
              figured to honor it. The easiest way to do  this  is  to  invoke
              ovsdb-server             with             the             option
              --remote=db:Open_vSwitch,Open_vSwitch,manager_options        The
              startup scripts that accompany Open vSwitch do this by default.

     IPsec:

       These  settings  control the global configuration of IPsec tunnels. The
       options column of the Interface table configures IPsec  for  individual
       tunnels.

       OVS  IPsec  supports  the following three forms of authentication. Cur‐
       rently, all IPsec tunnels must use the same form:

              1.  Pre-shared keys: Omit the global settings. On  each  tunnel,
                  set options:psk.

              2.  Self-signed  certificates:  Set the private_key and certifi‐
                  cate    global    settings.    On    each    tunnel,     set
                  options:remote_cert.  The  remote  certificate  can be self-
                  signed.

              3.  CA-signed certificates: Set all of the global  settings.  On
                  each tunnel, set options:remote_name to the common name (CN)
                  of the remote certificate. The remote  certificate  must  be
                  signed by the CA.

       other_config : private_key: optional string
              Name  of  a  PEM  file  containing  the  private key used as the
              switch’s identity for IPsec tunnels.

       other_config : certificate: optional string
              Name of a PEM file containing a certificate that  certifies  the
              switch’s  private  key,  and identifies a trustworthy switch for
              IPsec tunnels. The certificate must be x.509 version 3 and  with
              the  string in common name (CN) also set in the subject alterna‐
              tive name (SAN).

       other_config : ca_cert: optional string
              Name of a PEM file containing the CA certificate used to  verify
              that a remote switch of the IPsec tunnel is trustworthy.

     Plaintext Tunnel Policy:

       When  an IPsec tunnel is configured in this database, multiple indepen‐
       dent components take responsibility for implementing  it.  ovs-vswitchd
       and  its datapath handle packet forwarding to the tunnel and a separate
       daemon pushes the tunnel’s IPsec policy configuration to the kernel  or
       other entity that implements it. There is a race: if the former config‐
       uration completes before the latter, then packets  sent  by  the  local
       host  over  the tunnel can be transmitted in plaintext. Using this set‐
       ting, OVS users can avoid this undesirable situation.

       other_config : ipsec_skb_mark: optional string
              This setting takes the form value/mask. If it is specified, then
              the  skb_mark  field  in  every outgoing tunneled packet sent in
              plaintext is compared against it and, if it matches, the  packet
              is  dropped.  This  is a global setting that is applied to every
              tunneled packet,  regardless  of  whether  IPsec  encryption  is
              enabled  for  the  tunnel, the type of tunnel, or whether OVS is
              involved.

              Example policies:

              1/1    Drop all unencrypted tunneled packets in which the least-
                     significant  bit of skb_mark is 1. This would be a useful
                     policy given an OpenFlow flow table that sets skb_mark to
                     1  for  traffic  that  should  be  encrypted. The default
                     skb_mark is 0, so this would not affect other traffic.

              0/1    Drop all unencrypted tunneled packets in which the least-
                     significant  bit of skb_mark is 0. This would be a useful
                     policy if no unencrypted tunneled traffic should exit the
                     system  without  being  specially  permitted  by  setting
                     skb_mark to 1.

              (empty)
                     If this setting is empty or unset, then  all  unencrypted
                     tunneled packets are transmitted in the usual way.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Bridge TABLE
       Configuration for a bridge within an Open_vSwitch.

       A Bridge  record  represents  an  Ethernet  switch  with  one  or  more
       ``ports,’’  which are the Port records pointed to by the Bridge’s ports
       column.

   Summary:
       Core Features:
         name                        immutable string (must be  unique  within
                                     table)
         ports                       set of Ports
         mirrors                     set of Mirrors
         netflow                     optional NetFlow
         sflow                       optional sFlow
         ipfix                       optional IPFIX
         flood_vlans                 set  of  up to 4,096 integers, in range 0
                                     to 4,095
         auto_attach                 optional AutoAttach
       OpenFlow Configuration:
         controller                  set of Controllers
         flow_tables                 map of integer-Flow_Table pairs,  key  in
                                     range 0 to 254
         fail_mode                   optional  string, either secure or stand‐
                                     alone
         datapath_id                 optional string
         datapath_version            string
         other_config : datapath-id  optional string
         other_config : dp-desc      optional string
         other_config : dp-sn        optional string
         other_config : disable-in-band
                                     optional string, either true or false
         other_config : in-band-queue
                                     optional string, containing  an  integer,
                                     in range 0 to 4,294,967,295
         other_config : controller-queue-size
                                     optional  string,  containing an integer,
                                     in range 1 to 512
         protocols                   set of strings, one of OpenFlow10,  Open‐
                                     Flow11,   OpenFlow12,  OpenFlow13,  Open‐
                                     Flow14, or OpenFlow15
       Spanning Tree Configuration:
         STP Configuration:
            stp_enable               boolean
            other_config : stp-system-id
                                     optional string
            other_config : stp-priority
                                     optional string, containing  an  integer,
                                     in range 0 to 65,535
            other_config : stp-hello-time
                                     optional  string,  containing an integer,
                                     in range 1 to 10
            other_config : stp-max-age
                                     optional string, containing  an  integer,
                                     in range 6 to 40
            other_config : stp-forward-delay
                                     optional  string,  containing an integer,
                                     in range 4 to 30
            other_config : mcast-snooping-aging-time
                                     optional string, containing  an  integer,
                                     at least 1
            other_config : mcast-snooping-table-size
                                     optional  string,  containing an integer,
                                     at least 1
            other_config : mcast-snooping-disable-flood-unregistered
                                     optional string, either true or false
         STP Status:
            status : stp_bridge_id   optional string
            status : stp_designated_root
                                     optional string
            status : stp_root_path_cost
                                     optional string
       Rapid Spanning Tree:
         RSTP Configuration:
            rstp_enable              boolean
            other_config : rstp-address
                                     optional string
            other_config : rstp-priority
                                     optional string, containing  an  integer,
                                     in range 0 to 61,440
            other_config : rstp-ageing-time
                                     optional  string,  containing an integer,
                                     in range 10 to 1,000,000
            other_config : rstp-force-protocol-version
                                     optional string, containing an integer
            other_config : rstp-max-age
                                     optional string, containing  an  integer,
                                     in range 6 to 40
            other_config : rstp-forward-delay
                                     optional  string,  containing an integer,
                                     in range 4 to 30
            other_config : rstp-transmit-hold-count
                                     optional string, containing  an  integer,
                                     in range 1 to 10
         RSTP Status:
            rstp_status : rstp_bridge_id
                                     optional string
            rstp_status : rstp_root_id
                                     optional string
            rstp_status : rstp_root_path_cost
                                     optional  string,  containing an integer,
                                     at least 0
            rstp_status : rstp_designated_id
                                     optional string
            rstp_status : rstp_designated_port_id
                                     optional string
            rstp_status : rstp_bridge_port_id
                                     optional string
       Multicast Snooping Configuration:
         mcast_snooping_enable       boolean
       Other Features:
         datapath_type               string
         external_ids : bridge-id    optional string
         external_ids : xs-network-uuids
                                     optional string
         other_config : hwaddr       optional string
         other_config : forward-bpdu
                                     optional string, either true or false
         other_config : mac-aging-time
                                     optional string, containing  an  integer,
                                     at least 1
         other_config : mac-table-size
                                     optional  string,  containing an integer,
                                     at least 1
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
     Core Features:

       name: immutable string (must be unique within table)
              Bridge identifier. Must be unique  among  the  names  of  ports,
              interfaces, and bridges on a host.

              The  name  must  be alphanumeric and must not contain forward or
              backward slashes. The name of a bridge is also the  name  of  an
              Interface (and a Port) within the bridge, so the restrictions on
              the name column in the Interface table, particularly on  length,
              also  apply  to  bridge  names.  Refer  to the documentation for
              Interface names for details.

       ports: set of Ports
              Ports included in the bridge.

       mirrors: set of Mirrors
              Port mirroring configuration.

       netflow: optional NetFlow
              NetFlow configuration.

       sflow: optional sFlow
              sFlow(R) configuration.

       ipfix: optional IPFIX
              IPFIX configuration.

       flood_vlans: set of up to 4,096 integers, in range 0 to 4,095
              VLAN IDs of VLANs on which MAC address learning should  be  dis‐
              abled, so that packets are flooded instead of being sent to spe‐
              cific ports that are believed to  contain  packets’  destination
              MACs.  This should ordinarily be used to disable MAC learning on
              VLANs used for mirroring (RSPAN VLANs). It may  also  be  useful
              for debugging.

              SLB  bonding  (see  the  bond_mode  column in the Port table) is
              incompatible with flood_vlans. Consider  using  another  bonding
              mode or a different type of mirror instead.

       auto_attach: optional AutoAttach
              Auto Attach configuration.

     OpenFlow Configuration:

       controller: set of Controllers
              OpenFlow  controller set. If unset, then no OpenFlow controllers
              will be used.

              If there are primary controllers, removing all  of  them  clears
              the OpenFlow flow tables, group table, and meter table. If there
              are no primary controllers, adding one also clears these tables.
              Other  changes  to  the  set  of  controllers, such as adding or
              removing a service controller, adding another primary controller
              to  supplement  an existing primary controller, or removing only
              one of two primary controllers, have no effect on these tables.

       flow_tables: map of integer-Flow_Table pairs, key in range 0 to 254
              Configuration for OpenFlow tables. Each pair maps from an  Open‐
              Flow table ID to configuration for that table.

       fail_mode: optional string, either secure or standalone
              When  a controller is configured, it is, ordinarily, responsible
              for setting up all flows on the switch. Thus, if the  connection
              to  the  controller fails, no new network connections can be set
              up. If the connection to the controller stays down long  enough,
              no  packets  can  pass  through  the switch at all. This setting
              determines the switch’s response to such a situation. It may  be
              set to one of the following:

              standalone
                     If  no  message is received from the controller for three
                     times  the  inactivity  probe  interval   (see   inactiv‐
                     ity_probe), then Open vSwitch will take over responsibil‐
                     ity for setting up flows.  In  this  mode,  Open  vSwitch
                     causes  the  bridge  to act like an ordinary MAC-learning
                     switch. Open vSwitch will continue to retry connecting to
                     the controller in the background and, when the connection
                     succeeds, it will discontinue its standalone behavior.

              secure Open vSwitch will not set up flows on its  own  when  the
                     controller  connection  fails  or when no controllers are
                     defined. The bridge will continue to retry connecting  to
                     any defined controllers forever.

              The default is standalone if the value is unset, but future ver‐
              sions of Open vSwitch may change the default.

              The standalone mode can create forwarding loops on a bridge that
              has  more  than  one uplink port unless STP is enabled. To avoid
              loops on such a bridge, configure secure mode or enable STP (see
              stp_enable).

              The  fail_mode setting applies only to primary controllers. When
              more than one primary controller  is  configured,  fail_mode  is
              considered  only  when none of the configured controllers can be
              contacted.

              Changing fail_mode when no primary  controllers  are  configured
              clears the OpenFlow flow tables, group table, and meter table.

       datapath_id: optional string
              Reports  the OpenFlow datapath ID in use. Exactly 16 hex digits.
              (Setting this  column  has  no  useful  effect.  Set  other-con‐
              fig:datapath-id instead.)

       datapath_version: string
              Reports  the  datapath  version.  This  column is maintained for
              backwards compatibility. The preferred locatation is  the  data‐
              path_id column of the Datapath table. The full documentation for
              this column is there.

       other_config : datapath-id: optional string
              Overrides the default OpenFlow datapath ID, setting  it  to  the
              specified  value  specified in hex. The value must either have a
              0x prefix or be exactly 16 hex digits long. May not be all-zero.

       other_config : dp-desc: optional string
              Human readable description of datapath.  It  is  a  maximum  256
              byte-long  free-form  string to describe the datapath for debug‐
              ging purposes, e.g. switch3 in room 3120. The value is  returned
              by  the  switch  as  a  part  of  reply  to  OFPMP_DESC  request
              (ofp_desc). The OpenFlow specification  (e.g.  1.3.5)  describes
              the  ofp_desc  structure  to  contaion  "NULL  terminated  ASCII
              strings". For the compatibility reasons no more than  255  ASCII
              characters should be used.

       other_config : dp-sn: optional string
              Serial  number. It is a maximum 32 byte-long free-form string to
              provide  an  additional  switch  identification.  The  value  is
              returned  by the switch as a part of reply to OFPMP_DESC request
              (ofp_desc). Same as mentioned in the description  of  other-con‐
              fig:dp-desc,  the string should be no more than 31 ASCII charac‐
              ters for the compatibility.

       other_config : disable-in-band: optional string, either true or false
              If set to true, disable in-band control on the bridge regardless
              of controller and manager settings.

       other_config  :  in-band-queue: optional string, containing an integer,
       in range 0 to 4,294,967,295
              A queue ID as a nonnegative  integer.  This  sets  the  OpenFlow
              queue ID that will be used by flows set up by in-band control on
              this bridge. If unset, or if the port used by an in-band control
              flow  does not have QoS configured, or if the port does not have
              a queue with  the  specified  ID,  the  default  queue  is  used
              instead.

       other_config  :  controller-queue-size:  optional string, containing an
       integer, in range 1 to 512
              This sets the maximum size of the queue of packets that need  to
              be sent to the OpenFlow management controller. The value must be
              less than 512. If not specified the queue size is limited to 100
              packets by default. Note: increasing the queue size might have a
              negative impact on latency.

       protocols: set of strings, one of OpenFlow10,  OpenFlow11,  OpenFlow12,
       OpenFlow13, OpenFlow14, or OpenFlow15
              List  of  OpenFlow protocols that may be used when negotiating a
              connection with a controller. OpenFlow 1.0, 1.1, 1.2, 1.3,  1.4,
              and 1.5 are enabled by default if this column is empty.

     Spanning Tree Configuration:

       The IEEE 802.1D Spanning Tree Protocol (STP) is a network protocol that
       ensures loop-free topologies. It allows redundant links to be  included
       in  the  network  to provide automatic backup paths if the active links
       fails.

       These settings configure the slower-to-converge but still  widely  sup‐
       ported   version   of   Spanning  Tree  Protocol,  sometimes  known  as
       802.1D-1998. Open vSwitch also supports the newer Rapid  Spanning  Tree
       Protocol  (RSTP), documented later in the section titled Rapid Spanning
       Tree Configuration.

     STP Configuration:

       stp_enable: boolean
              Enable spanning tree on the bridge. By default, STP is  disabled
              on  bridges.  Bond, internal, and mirror ports are not supported
              and will not participate in the spanning tree.

              STP and RSTP are mutually exclusive. If both are  enabled,  RSTP
              will be used.

       other_config : stp-system-id: optional string
              The bridge’s STP identifier (the lower 48 bits of the bridge-id)
              in the form xx:xx:xx:xx:xx:xx. By default, the identifier is the
              MAC address of the bridge.

       other_config : stp-priority: optional string, containing an integer, in
       range 0 to 65,535
              The bridge’s relative priority value for  determining  the  root
              bridge  (the  upper 16 bits of the bridge-id). A bridge with the
              lowest bridge-id is elected the root. By default,  the  priority
              is 0x8000.

       other_config  : stp-hello-time: optional string, containing an integer,
       in range 1 to 10
              The interval between transmissions of hello messages  by  desig‐
              nated ports, in seconds. By default the hello interval is 2 sec‐
              onds.

       other_config : stp-max-age: optional string, containing an integer,  in
       range 6 to 40
              The  maximum  age  of  the information transmitted by the bridge
              when it is the root bridge, in seconds. By default, the  maximum
              age is 20 seconds.

       other_config  : stp-forward-delay: optional string, containing an inte‐
       ger, in range 4 to 30
              The delay to wait  between  transitioning  root  and  designated
              ports  to  forwarding,  in  seconds.  By default, the forwarding
              delay is 15 seconds.

       other_config : mcast-snooping-aging-time: optional  string,  containing
       an integer, at least 1
              The  maximum  number  of  seconds to retain a multicast snooping
              entry for which no packets have been seen. The default  is  cur‐
              rently  300  seconds  (5  minutes).  The value, if specified, is
              forced into a reasonable range, currently 15 to 3600 seconds.

       other_config : mcast-snooping-table-size: optional  string,  containing
       an integer, at least 1
              The maximum number of multicast snooping addresses to learn. The
              default is currently 2048. The value, if  specified,  is  forced
              into a reasonable range, currently 10 to 1,000,000.

       other_config   :   mcast-snooping-disable-flood-unregistered:  optional
       string, either true or false
              If set to false, unregistered multicast packets are forwarded to
              all  ports.  If  set to true, unregistered multicast packets are
              forwarded to ports connected to multicast routers.

     STP Status:

       These key-value pairs  report  the  status  of  802.1D-1998.  They  are
       present only if STP is enabled (via the stp_enable column).

       status : stp_bridge_id: optional string
              The  bridge ID used in spanning tree advertisements, in the form
              xxxx.yyyyyyyyyyyy where the xs are the STP priority, the ys  are
              the STP system ID, and each x and y is a hex digit.

       status : stp_designated_root: optional string
              The  designated root for this spanning tree, in the same form as
              status:stp_bridge_id. If this bridge is the root, this will have
              the  same  value as status:stp_bridge_id, otherwise it will dif‐
              fer.

       status : stp_root_path_cost: optional string
              The path cost of reaching the designated bridge. A lower  number
              is  better. The value is 0 if this bridge is the root, otherwise
              it is higher.

     Rapid Spanning Tree:

       Rapid Spanning Tree Protocol (RSTP), like STP, is  a  network  protocol
       that  ensures loop-free topologies. RSTP superseded STP with the publi‐
       cation of 802.1D-2004. Compared to STP, RSTP converges more quickly and
       recovers more quickly from failures.

     RSTP Configuration:

       rstp_enable: boolean
              Enable  Rapid  Spanning  Tree on the bridge. By default, RSTP is
              disabled on bridges. Bond, internal, and mirror  ports  are  not
              supported and will not participate in the spanning tree.

              STP  and  RSTP are mutually exclusive. If both are enabled, RSTP
              will be used.

       other_config : rstp-address: optional string
              The bridge’s RSTP address (the lower 48 bits of  the  bridge-id)
              in  the  form  xx:xx:xx:xx:xx:xx. By default, the address is the
              MAC address of the bridge.

       other_config : rstp-priority: optional string, containing  an  integer,
       in range 0 to 61,440
              The  bridge’s  relative  priority value for determining the root
              bridge (the upper 16 bits of the bridge-id). A bridge  with  the
              lowest  bridge-id  is elected the root. By default, the priority
              is 0x8000 (32768). This value needs to be a  multiple  of  4096,
              otherwise it’s rounded to the nearest inferior one.

       other_config  :  rstp-ageing-time: optional string, containing an inte‐
       ger, in range 10 to 1,000,000
              The Ageing Time parameter for the Bridge. The default  value  is
              300 seconds.

       other_config : rstp-force-protocol-version: optional string, containing
       an integer
              The Force Protocol Version parameter for the  Bridge.  This  can
              take  the  value  0  (STP Compatibility mode) or 2 (the default,
              normal operation).

       other_config : rstp-max-age: optional string, containing an integer, in
       range 6 to 40
              The  maximum  age  of  the information transmitted by the Bridge
              when it is the Root Bridge. The default value is 20.

       other_config : rstp-forward-delay: optional string, containing an inte‐
       ger, in range 4 to 30
              The  delay used by STP Bridges to transition Root and Designated
              Ports to Forwarding. The default value is 15.

       other_config : rstp-transmit-hold-count: optional string, containing an
       integer, in range 1 to 10
              The  Transmit Hold Count used by the Port Transmit state machine
              to limit transmission rate. The default value is 6.

     RSTP Status:

       These key-value pairs  report  the  status  of  802.1D-2004.  They  are
       present only if RSTP is enabled (via the rstp_enable column).

       rstp_status : rstp_bridge_id: optional string
              The bridge ID used in rapid spanning tree advertisements, in the
              form x.yyy.zzzzzzzzzzzz where x is the RSTP priority, the ys are
              a  locally assigned system ID extension, the zs are the STP sys‐
              tem ID, and each x, y, or z is a hex digit.

       rstp_status : rstp_root_id: optional string
              The root of this spanning tree, in the same  form  as  rstp_sta‐
              tus:rstp_bridge_id.  If  this bridge is the root, this will have
              the same value as rstp_status:rstp_bridge_id, otherwise it  will
              differ.

       rstp_status : rstp_root_path_cost: optional string, containing an inte‐
       ger, at least 0
              The path cost of reaching the root. A lower  number  is  better.
              The  value  is  0  if  this  bridge is the root, otherwise it is
              higher.

       rstp_status : rstp_designated_id: optional string
              The  RSTP  designated  ID,  in  the  same  form   as   rstp_sta‐
              tus:rstp_bridge_id.

       rstp_status : rstp_designated_port_id: optional string
              The RSTP designated port ID, as a 4-digit hex number.

       rstp_status : rstp_bridge_port_id: optional string
              The RSTP bridge port ID, as a 4-digit hex number.

     Multicast Snooping Configuration:

       Multicast  snooping  (RFC  4541) monitors the Internet Group Management
       Protocol (IGMP) and Multicast Listener Discovery traffic between  hosts
       and  multicast  routers.  The  switch  uses  what IGMP and MLD snooping
       learns to forward multicast traffic only to interfaces  that  are  con‐
       nected  to  interested receivers. Currently it supports IGMPv1, IGMPv2,
       IGMPv3, MLDv1 and MLDv2 protocols.

       mcast_snooping_enable: boolean
              Enable multicast snooping on the bridge. For now, the default is
              disabled.

     Other Features:

       datapath_type: string
              Name  of datapath provider. The kernel datapath has type system.
              The userspace datapath has type netdev. A manager may  refer  to
              the  datapath_types  column of the Open_vSwitch table for a list
              of the types accepted by this Open vSwitch instance.

       external_ids : bridge-id: optional string
              A unique identifier of the bridge. On Citrix XenServer this will
              commonly be the same as external_ids:xs-network-uuids.

       external_ids : xs-network-uuids: optional string
              Semicolon-delimited  set of universally unique identifier(s) for
              the network with which this bridge is  associated  on  a  Citrix
              XenServer  host.  The  network identifiers are RFC 4122 UUIDs as
              displayed by, e.g., xe network-list.

       other_config : hwaddr: optional string
              An Ethernet address in the form  xx:xx:xx:xx:xx:xx  to  set  the
              hardware  address  of  the local port and influence the datapath
              ID.

       other_config : forward-bpdu: optional string, either true or false
              Controls forwarding of BPDUs and other  network  control  frames
              when  NORMAL  action  is  invoked.  When this option is false or
              unset, frames with reserved Ethernet addresses (see table below)
              will  not  be  forwarded.  When this option is true, such frames
              will not be treated specially.

              The above general rule has the following exceptions:

              ·      If STP is enabled on the bridge (see the stp_enable  col‐
                     umn  in  the  Bridge  table),  the  bridge  processes all
                     received STP packets and never passes them to OpenFlow or
                     forwards them. This is true even if STP is disabled on an
                     individual port.

              ·      If LLDP is enabled on an interface (see the  lldp  column
                     in the Interface table), the interface processes received
                     LLDP packets and never passes them to  OpenFlow  or  for‐
                     wards them.

              Set this option to true if the Open vSwitch bridge connects dif‐
              ferent Ethernet networks and is not configured to participate in
              STP.

              This  option  affects packets with the following destination MAC
              addresses:

              01:80:c2:00:00:00
                     IEEE 802.1D Spanning Tree Protocol (STP).

              01:80:c2:00:00:01
                     IEEE Pause frame.

              01:80:c2:00:00:0x
                     Other reserved protocols.

              00:e0:2b:00:00:00
                     Extreme Discovery Protocol (EDP).

              00:e0:2b:00:00:04 and 00:e0:2b:00:00:06
                     Ethernet Automatic Protection Switching (EAPS).

              01:00:0c:cc:cc:cc
                     Cisco Discovery Protocol (CDP),  VLAN  Trunking  Protocol
                     (VTP),  Dynamic Trunking Protocol (DTP), Port Aggregation
                     Protocol (PAgP), and others.

              01:00:0c:cc:cc:cd
                     Cisco Shared Spanning Tree Protocol PVSTP+.

              01:00:0c:cd:cd:cd
                     Cisco STP Uplink Fast.

              01:00:0c:00:00:00
                     Cisco Inter Switch Link.

              01:00:0c:cc:cc:cx
                     Cisco CFM.

       other_config : mac-aging-time: optional string, containing an  integer,
       at least 1
              The maximum number of seconds to retain a MAC learning entry for
              which no packets have been seen. The default  is  currently  300
              seconds  (5  minutes). The value, if specified, is forced into a
              reasonable range, currently 15 to 3600 seconds.

              A short MAC aging time allows a network to more  quickly  detect
              that a host is no longer connected to a switch port. However, it
              also makes it more likely that packets will be flooded  unneces‐
              sarily,  when they are addressed to a connected host that rarely
              transmits packets. To reduce the incidence of unnecessary flood‐
              ing,  use  a  MAC aging time longer than the maximum interval at
              which a host will ordinarily transmit packets.

       other_config : mac-table-size: optional string, containing an  integer,
       at least 1
              The  maximum  number  of  MAC addresses to learn. The default is
              currently 8192. The value, if specified, is forced into  a  rea‐
              sonable range, currently 10 to 1,000,000.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Port TABLE
       A port within a Bridge.

       Most commonly, a port has exactly one ``interface,’’ pointed to by  its
       interfaces  column.  Such  a  port logically corresponds to a port on a
       physical Ethernet switch. A port with more  than  one  interface  is  a
       ``bonded port’’ (see Bonding Configuration).

       Some  properties  that one might think as belonging to a port are actu‐
       ally part of the port’s Interface members.

   Summary:
       name                          immutable string (must be  unique  within
                                     table)
       interfaces                    set of 1 or more Interfaces
       VLAN Configuration:
         vlan_mode                   optional    string,    one   of   access,
                                     dot1q-tunnel,              native-tagged,
                                     native-untagged, or trunk
         tag                         optional integer, in range 0 to 4,095
         trunks                      set  of  up to 4,096 integers, in range 0
                                     to 4,095
         cvlans                      set of up to 4,096 integers, in  range  0
                                     to 4,095
         other_config : qinq-ethtype
                                     optional string, either 802.1ad or 802.1q
         other_config : priority-tags
                                     optional    string,    one   of   always,
                                     if-nonzero, or never
       Bonding Configuration:
         bond_mode                   optional string,  one  of  active-backup,
                                     balance-slb, or balance-tcp
         other_config : bond-hash-basis
                                     optional string, containing an integer
         other_config : lb-output-action
                                     optional string, either true or false
         other_config : bond-primary
                                     optional string
         Link Failure Detection:
            other_config : bond-detect-mode
                                     optional string, either carrier or miimon
            other_config : bond-miimon-interval
                                     optional string, containing an integer
            bond_updelay             integer
            bond_downdelay           integer
         LACP Configuration:
            lacp                     optional  string,  one of active, off, or
                                     passive
            other_config : lacp-system-id
                                     optional string
            other_config : lacp-system-priority
                                     optional string, containing  an  integer,
                                     in range 1 to 65,535
            other_config : lacp-time optional string, either fast or slow
            other_config : lacp-fallback-ab
                                     optional string, either true or false
         Rebalancing Configuration:
            other_config : bond-rebalance-interval
                                     optional  string,  containing an integer,
                                     in range 0 to 2,147,483,647
         bond_fake_iface             boolean
       Spanning Tree Protocol:
         STP Configuration:
            other_config : stp-enable
                                     optional string, either true or false
            other_config : stp-port-num
                                     optional string, containing  an  integer,
                                     in range 1 to 255
            other_config : stp-port-priority
                                     optional  string,  containing an integer,
                                     in range 0 to 255
            other_config : stp-path-cost
                                     optional string, containing  an  integer,
                                     in range 0 to 65,535
         STP Status:
            status : stp_port_id     optional string
            status : stp_state       optional  string,  one  of blocking, dis‐
                                     abled, forwarding, learning, or listening
            status : stp_sec_in_state
                                     optional string, containing  an  integer,
                                     at least 0
            status : stp_role        optional string, one of alternate, desig‐
                                     nated, or root
       Rapid Spanning Tree Protocol:
         RSTP Configuration:
            other_config : rstp-enable
                                     optional string, either true or false
            other_config : rstp-port-priority
                                     optional string, containing  an  integer,
                                     in range 0 to 240
            other_config : rstp-port-num
                                     optional  string,  containing an integer,
                                     in range 1 to 4,095
            other_config : rstp-port-path-cost
                                     optional string, containing an integer
            other_config : rstp-port-admin-edge
                                     optional string, either true or false
            other_config : rstp-port-auto-edge
                                     optional string, either true or false
            other_config : rstp-port-mcheck
                                     optional string, either true or false
         RSTP Status:
            rstp_status : rstp_port_id
                                     optional string
            rstp_status : rstp_port_role
                                     optional  string,   one   of   Alternate,
                                     Backup, Designated, Disabled, or Root
            rstp_status : rstp_port_state
                                     optional  string,  one  of Disabled, Dis‐
                                     carding, Forwarding, or Learning
            rstp_status : rstp_designated_bridge_id
                                     optional string
            rstp_status : rstp_designated_port_id
                                     optional string
            rstp_status : rstp_designated_path_cost
                                     optional string, containing an integer
         RSTP Statistics:
            rstp_statistics : rstp_tx_count
                                     optional integer
            rstp_statistics : rstp_rx_count
                                     optional integer
            rstp_statistics : rstp_error_count
                                     optional integer
            rstp_statistics : rstp_uptime
                                     optional integer
       Multicast Snooping:
         other_config : mcast-snooping-flood
                                     optional string, either true or false
         other_config : mcast-snooping-flood-reports
                                     optional string, either true or false
       Other Features:
         qos                         optional QoS
         mac                         optional string
         fake_bridge                 boolean
         protected                   boolean
         external_ids : fake-bridge-id-*
                                     optional string
         other_config : transient    optional string, either true or false
       bond_active_slave             optional string
       Port Statistics:
         Statistics: STP transmit and receive counters:
            statistics : stp_tx_count
                                     optional integer
            statistics : stp_rx_count
                                     optional integer
            statistics : stp_error_count
                                     optional integer
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
       name: immutable string (must be unique within table)
              Port name. For a non-bonded port, this should be the same as its
              interface’s  name. Port names must otherwise be unique among the
              names of ports, interfaces, and bridges on a host. Because  port
              and  interfaces  names are usually the same, the restrictions on
              the name column in the Interface table, particularly on  length,
              also  apply to port names. Refer to the documentation for Inter‐
              face names for details.

       interfaces: set of 1 or more Interfaces
              The port’s interfaces. If there is more  than  one,  this  is  a
              bonded Port.

     VLAN Configuration:

       In  short,  a  VLAN (short for ``virtual LAN’’) is a way to partition a
       single switch into multiple switches. VLANs can be confusing, so for an
       introduction,  please  refer  to the question ``What’s a VLAN?’’ in the
       Open vSwitch FAQ.

       A VLAN is sometimes encoded into a packet using  a  802.1Q  or  802.1ad
       VLAN header, but every packet is part of some VLAN whether or not it is
       encoded in the packet. (A packet that appears to have no VLAN  is  part
       of  VLAN 0, by default.) As a result, it’s useful to think of a VLAN as
       a metadata property of a packet, separate from how the VLAN is encoded.
       For  a  given port, this column determines how the encoding of a packet
       that ingresses or egresses the port maps to the packet’s VLAN.  When  a
       packet  enters  the switch, its VLAN is determined based on its setting
       in this column and its VLAN headers, if any,  and  then,  conceptually,
       the VLAN headers are then stripped off. Conversely, when a packet exits
       the switch, its VLAN and the settings in  this  column  determine  what
       VLAN headers, if any, are pushed onto the packet before it egresses the
       port.

       The VLAN configuration in this column affects Open vSwitch only when it
       is  doing  ``normal  switching.’’ It does not affect flows set up by an
       OpenFlow controller, outside of the OpenFlow ``normal action.’’

       Bridge ports support the following types of VLAN configuration:

              trunk  A trunk port carries packets on  one  or  more  specified
                     VLANs  specified  in  the  trunks column (often, on every
                     VLAN). A packet that ingresses on a trunk port is in  the
                     VLAN  specified  in  its  802.1Q header, or VLAN 0 if the
                     packet has no  802.1Q  header.  A  packet  that  egresses
                     through a trunk port will have an 802.1Q header if it has
                     a nonzero VLAN ID.

                     Any packet that ingresses on a trunk port tagged  with  a
                     VLAN that the port does not trunk is dropped.

              access An access port carries packets on exactly one VLAN speci‐
                     fied in the tag column. Packets egressing  on  an  access
                     port have no 802.1Q header.

                     Any  packet  with an 802.1Q header with a nonzero VLAN ID
                     that ingresses on an access port is  dropped,  regardless
                     of whether the VLAN ID in the header is the access port’s
                     VLAN ID.

              native-tagged
                     A native-tagged port resembles a  trunk  port,  with  the
                     exception  that  a  packet  without an 802.1Q header that
                     ingresses on a native-tagged  port  is  in  the  ``native
                     VLAN’’ (specified in the tag column).

              native-untagged
                     A  native-untagged  port  resembles a native-tagged port,
                     with the exception that  a  packet  that  egresses  on  a
                     native-untagged  port in the native VLAN will not have an
                     802.1Q header.

              dot1q-tunnel
                     A dot1q-tunnel port is somewhat like an access port. Like
                     an  access  port,  it  carries packets on the single VLAN
                     specified in the tag column and  this  VLAN,  called  the
                     service  VLAN,  does  not  appear in an 802.1Q header for
                     packets that ingress or egress on the port. The main dif‐
                     ference  lies in the behavior when packets that include a
                     802.1Q header ingress on the port. Whereas an access port
                     drops  such  packets, a dot1q-tunnel port treats these as
                     double-tagged with the outer service  VLAN  tag  and  the
                     inner  customer VLAN taken from the 802.1Q header. Corre‐
                     spondingly, to egress on the port, a  packet  outer  VLAN
                     (or  only  VLAN)  must  be  tag,  which is removed before
                     egress, which exposes the inner (customer) VLAN if one is
                     present.

                     If  cvlans  is  set, only allows packets in the specified
                     customer VLANs.

       A packet will only egress through bridge ports that carry the  VLAN  of
       the packet, as described by the rules above.

       vlan_mode: optional string, one of access, dot1q-tunnel, native-tagged,
       native-untagged, or trunk
              The VLAN mode of the port, as described above. When this  column
              is empty, a default mode is selected as follows:

              ·      If  tag contains a value, the port is an access port. The
                     trunks column should be empty.

              ·      Otherwise, the port is a trunk port.  The  trunks  column
                     value is honored if it is present.

       tag: optional integer, in range 0 to 4,095
              For  an  access  port,  the port’s implicitly tagged VLAN. For a
              native-tagged or native-untagged port, the port’s  native  VLAN.
              Must be empty if this is a trunk port.

       trunks: set of up to 4,096 integers, in range 0 to 4,095
              For  a trunk, native-tagged, or native-untagged port, the 802.1Q
              VLAN or VLANs that this port trunks; if it is  empty,  then  the
              port trunks all VLANs. Must be empty if this is an access port.

              A native-tagged or native-untagged port always trunks its native
              VLAN, regardless of whether trunks includes that VLAN.

       cvlans: set of up to 4,096 integers, in range 0 to 4,095
              For a dot1q-tunnel port,  the  customer  VLANs  that  this  port
              includes.  If  this  is  empty,  the  port includes all customer
              VLANs.

              For other kinds of ports, this setting is ignored.

       other_config : qinq-ethtype: optional string, either 802.1ad or 802.1q
              For a dot1q-tunnel port, this is the TPID for the  service  tag,
              that  is,  for  the 802.1Q header that contains the service VLAN
              ID. Because packets that actually ingress and  egress  a  dot1q-
              tunnel  port  do  not  include  an 802.1Q header for the service
              VLAN, this does not affect  packets  on  the  dot1q-tunnel  port
              itself. Rather, it determines the service VLAN for a packet that
              ingresses on a dot1q-tunnel port and egresses on a trunk port.

              The value 802.1ad specifies  TPID  0x88a8,  which  is  also  the
              default  if  the  setting is omitted. The value 802.1q specifies
              TPID 0x8100.

              For other kinds of ports, this setting is ignored.

       other_config  :  priority-tags:  optional  string,   one   of   always,
       if-nonzero, or never
              An 802.1Q header contains two important pieces of information: a
              VLAN ID and a priority. A frame with a zero VLAN  ID,  called  a
              ``priority-tagged’’  frame,  is  supposed to be treated the same
              way as a frame without an 802.1Q header at all (except  for  the
              priority).

              However,  some network elements ignore any frame that has 802.1Q
              header at all, even when the VLAN  ID  is  zero.  Therefore,  by
              default  Open  vSwitch  does  not output priority-tagged frames,
              instead omitting the 802.1Q header entirely if the  VLAN  ID  is
              zero.  Set  this  key  to  if-nonzero  to enable priority-tagged
              frames on a port.

              For if-nonzero Open vSwitch omits the 802.1Q header on output if
              both  the  VLAN  ID and priority would be zero. Set to always to
              retain the 802.1Q header in such frames as well.

              All frames output to native-tagged ports have a nonzero VLAN ID,
              so this setting is not meaningful on native-tagged ports.

     Bonding Configuration:

       A  port  that has more than one interface is a ``bonded port.’’ Bonding
       allows for load balancing and fail-over.

       The following types of bonding will work  with  any  kind  of  upstream
       switch.  On  the  upstream switch, do not configure the interfaces as a
       bond:

              balance-slb
                     Balances flows among members based on source MAC  address
                     and  output  VLAN,  with  periodic rebalancing as traffic
                     patterns change.

              active-backup
                     Assigns all flows to one member, failing over to a backup
                     member  when  the  active member is disabled. This is the
                     only bonding mode in which interfaces may be plugged into
                     different upstream switches.

       The following modes require the upstream switch to support 802.3ad with
       successful LACP negotiation. If LACP negotiation fails  and  other-con‐
       fig:lacp-fallback-ab is true, then active-backup mode is used:

              balance-tcp
                     Balances  flows among members based on L3 and L4 protocol
                     information such as IP addresses and TCP/UDP ports.

       These columns apply only to bonded ports. Their  values  are  otherwise
       ignored.

       bond_mode:  optional string, one of active-backup, balance-slb, or bal‐
       ance-tcp
              The type  of  bonding  used  for  a  bonded  port.  Defaults  to
              active-backup if unset.

       other_config : bond-hash-basis: optional string, containing an integer
              An  integer hashed along with flows when choosing output members
              in load balanced bonds. When changed, all flows will be assigned
              different  hash  values  possibly causing member selection deci‐
              sions to change. Does not affect  bonding  modes  which  do  not
              employ load balancing such as active-backup.

       other_config : lb-output-action: optional string, either true or false
              Enable/disable usage of optimized lb_output action for balancing
              flows among output  members  in  load  balanced  bonds  in  bal‐
              ance-tcp.  When  enabled, it uses optimized path for balance-tcp
              mode by using rss hash and avoids recirculation. This knob  does
              not affect other balancing modes.

       other_config : bond-primary: optional string
              If  a  slave  interface with this name exists in the bond and is
              up, it will  be  made  active.  Relevant  only  when  other_con‐
              fig:bond_mode  is  active-backup or if balance-tcp falls back to
              active-backup  (e.g.,  LACP  negotiation  fails  and  other_con‐
              fig:lacp-fallback-ab is true).

     Link Failure Detection:

       An  important  part of link bonding is detecting that links are down so
       that they may be disabled. These settings determine  how  Open  vSwitch
       detects link failure.

       other_config  :  bond-detect-mode:  optional  string, either carrier or
       miimon
              The means used to detect  link  failures.  Defaults  to  carrier
              which uses each interface’s carrier to detect failures. When set
              to miimon, will check for failures by polling  each  interface’s
              MII.

       other_config  :  bond-miimon-interval:  optional  string, containing an
       integer
              The interval, in milliseconds, between  successive  attempts  to
              poll each interface’s MII. Relevant only when other_config:bond-
              detect-mode is miimon.

       bond_updelay: integer
              The number of milliseconds for which the link must stay up on an
              interface before the interface is considered to be up. Specify 0
              to enable the interface immediately.

              This setting is honored only when at least one bonded  interface
              is  already  enabled.  When  no interfaces are enabled, then the
              first bond interface to come up is enabled immediately.

       bond_downdelay: integer
              The number of milliseconds for which the link must stay down  on
              an  interface  before  the  interface  is considered to be down.
              Specify 0 to disable the interface immediately.

     LACP Configuration:

       LACP, the Link Aggregation Control Protocol, is an IEEE  standard  that
       allows switches to automatically detect that they are connected by mul‐
       tiple links and aggregate across those links.  These  settings  control
       LACP behavior.

       lacp: optional string, one of active, off, or passive
              Configures  LACP  on  this  port. LACP allows directly connected
              switches to negotiate which links may be  bonded.  LACP  may  be
              enabled on non-bonded ports for the benefit of any switches they
              may be connected to. active ports are allowed to  initiate  LACP
              negotiations.  passive  ports are allowed to participate in LACP
              negotiations initiated by a remote switch, but  not  allowed  to
              initiate  such  negotiations themselves. If LACP is enabled on a
              port whose partner switch does not support LACP, the  bond  will
              be  disabled,  unless  other-config:lacp-fallback-ab  is  set to
              true. Defaults to off if unset.

       other_config : lacp-system-id: optional string
              The LACP system ID of this Port. The system ID of a LACP bond is
              used  to  identify itself to its partners. Must be a nonzero MAC
              address. Defaults to the bridge Ethernet address if unset.

       other_config : lacp-system-priority:  optional  string,  containing  an
       integer, in range 1 to 65,535
              The  LACP  system  priority  of this Port. In LACP negotiations,
              link status decisions are made by the system  with  the  numeri‐
              cally lower priority.

       other_config : lacp-time: optional string, either fast or slow
              The  LACP  timing  which should be used on this Port. By default
              slow is used. When configured to be  fast  LACP  heartbeats  are
              requested  at  a  rate  of  once per second causing connectivity
              problems to be detected more quickly. In slow  mode,  heartbeats
              are requested at a rate of once every 30 seconds.

       other_config : lacp-fallback-ab: optional string, either true or false
              Determines the behavior of openvswitch bond in LACP mode. If the
              partner switch does not support LACP,  setting  this  option  to
              true  allows  openvswitch  to  fallback to active-backup. If the
              option is set to false, the bond will be disabled. In  both  the
              cases,  once  the partner switch is configured to LACP mode, the
              bond will use LACP.

     Rebalancing Configuration:

       These settings control behavior when a bond is in balance-slb  or  bal‐
       ance-tcp mode.

       other_config  : bond-rebalance-interval: optional string, containing an
       integer, in range 0 to 2,147,483,647
              For a load balanced bonded  port,  the  number  of  milliseconds
              between  successive  attempts to rebalance the bond, that is, to
              move flows from one interface on  the  bond  to  another  in  an
              attempt  to keep usage of each interface roughly equal. If zero,
              load balancing is disabled on the bond (link failure still cause
              flows to move). If less than 1000ms, the rebalance interval will
              be 1000ms.

       bond_fake_iface: boolean
              For a bonded port, whether to create a fake  internal  interface
              with  the  name  of  the  port.  Use only for compatibility with
              legacy software that requires this.

     Spanning Tree Protocol:

       The configuration here is only meaningful, and the status is only popu‐
       lated, when 802.1D-1998 Spanning Tree Protocol is enabled on the port’s
       Bridge with its stp_enable column.

     STP Configuration:

       other_config : stp-enable: optional string, either true or false
              When STP is enabled on a bridge, it is enabled by default on all
              of  the  bridge’s  ports except bond, internal, and mirror ports
              (which do not work with STP). If this column’s value  is  false,
              STP is disabled on the port.

       other_config : stp-port-num: optional string, containing an integer, in
       range 1 to 255
              The port number used for the lower 8 bits  of  the  port-id.  By
              default,  the  numbers  will  be  assigned automatically. If any
              port’s number is manually configured on a bridge, then they must
              all be.

       other_config  : stp-port-priority: optional string, containing an inte‐
       ger, in range 0 to 255
              The port’s relative priority value for determining the root port
              (the  upper  8 bits of the port-id). A port with a lower port-id
              will be chosen as the root port. By  default,  the  priority  is
              0x80.

       other_config  :  stp-path-cost: optional string, containing an integer,
       in range 0 to 65,535
              Spanning tree path cost for the port. A lower number indicates a
              faster  link. By default, the cost is based on the maximum speed
              of the link.

     STP Status:

       status : stp_port_id: optional string
              The port ID used in spanning tree advertisements for this  port,
              as  4  hex  digits.  Configuring the port ID is described in the
              stp-port-num and stp-port-priority keys of the other_config sec‐
              tion earlier.

       status  :  stp_state:  optional string, one of blocking, disabled, for‐
       warding, learning, or listening
              STP state of the port.

       status : stp_sec_in_state: optional string, containing an  integer,  at
       least 0
              The  amount of time this port has been in the current STP state,
              in seconds.

       status : stp_role: optional string, one of  alternate,  designated,  or
       root
              STP role of the port.

     Rapid Spanning Tree Protocol:

       The  configuration  here is only meaningful, and the status and statis‐
       tics are only populated, when 802.1D-1998  Spanning  Tree  Protocol  is
       enabled on the port’s Bridge with its stp_enable column.

     RSTP Configuration:

       other_config : rstp-enable: optional string, either true or false
              When  RSTP  is  enabled on a bridge, it is enabled by default on
              all of the bridge’s ports  except  bond,  internal,  and  mirror
              ports  (which  do not work with RSTP). If this column’s value is
              false, RSTP is disabled on the port.

       other_config : rstp-port-priority: optional string, containing an inte‐
       ger, in range 0 to 240
              The  port’s  relative  priority  value  for determining the root
              port, in multiples of 16. By default, the port priority is  0x80
              (128). Any value in the lower 4 bits is rounded off. The signif‐
              icant upper 4 bits become the upper 4 bits  of  the  port-id.  A
              port with the lowest port-id is elected as the root.

       other_config  :  rstp-port-num: optional string, containing an integer,
       in range 1 to 4,095
              The local RSTP port number, used as the lower  12  bits  of  the
              port-id. By default the port numbers are assigned automatically,
              and typically may not correspond to the OpenFlow port numbers. A
              port with the lowest port-id is elected as the root.

       other_config  :  rstp-port-path-cost:  optional  string,  containing an
       integer
              The port path cost. The Port’s contribution, when it is the Root
              Port,  to the Root Path Cost for the Bridge. By default the cost
              is automatically calculated from the port’s speed.

       other_config : rstp-port-admin-edge: optional string,  either  true  or
       false
              The admin edge port parameter for the Port. Default is false.

       other_config  :  rstp-port-auto-edge:  optional  string, either true or
       false
              The auto edge port parameter for the Port. Default is true.

       other_config : rstp-port-mcheck: optional string, either true or false
              The mcheck port parameter for the Port. Default is false. May be
              set to force the Port Protocol Migration state machine to trans‐
              mit RST BPDUs for a MigrateTime period, to test whether all  STP
              Bridges  on  the attached LAN have been removed and the Port can
              continue to transmit RSTP BPDUs. Setting mcheck has no effect if
              the Bridge is operating in STP Compatibility mode.

              Changing  the  value from true to false has no effect, but needs
              to be done if this behavior is to be triggered again  by  subse‐
              quently changing the value from false to true.

     RSTP Status:

       rstp_status : rstp_port_id: optional string
              The  port ID used in spanning tree advertisements for this port,
              as 4 hex digits. Configuring the port ID  is  described  in  the
              rstp-port-num  and  rstp-port-priority  keys of the other_config
              section earlier.

       rstp_status  :  rstp_port_role:  optional  string,  one  of  Alternate,
       Backup, Designated, Disabled, or Root
              RSTP role of the port.

       rstp_status  :  rstp_port_state: optional string, one of Disabled, Dis‐
       carding, Forwarding, or Learning
              RSTP state of the port.

       rstp_status : rstp_designated_bridge_id: optional string
              The port’s RSTP designated  bridge  ID,  in  the  same  form  as
              rstp_status:rstp_bridge_id in the Bridge table.

       rstp_status : rstp_designated_port_id: optional string
              The port’s RSTP designated port ID, as 4 hex digits.

       rstp_status : rstp_designated_path_cost: optional string, containing an
       integer
              The port’s RSTP designated path cost. Lower is better.

     RSTP Statistics:

       rstp_statistics : rstp_tx_count: optional integer
              Number of RSTP BPDUs transmitted through this port.

       rstp_statistics : rstp_rx_count: optional integer
              Number of valid RSTP BPDUs received by this port.

       rstp_statistics : rstp_error_count: optional integer
              Number of invalid RSTP BPDUs received by this port.

       rstp_statistics : rstp_uptime: optional integer
              The duration covered by the other RSTP statistics, in seconds.

     Multicast Snooping:

       other_config : mcast-snooping-flood: optional string,  either  true  or
       false
              If  set to true, multicast packets (except Reports) are uncondi‐
              tionally forwarded to the specific port.

       other_config : mcast-snooping-flood-reports:  optional  string,  either
       true or false
              If  set to true, multicast Reports are unconditionally forwarded
              to the specific port.

     Other Features:

       qos: optional QoS
              Quality of Service configuration for this port.

       mac: optional string
              The MAC address to use for this port for the purpose of choosing
              the  bridge’s  MAC  address.  This  column  does not necessarily
              reflect the port’s actual  MAC  address,  nor  will  setting  it
              change the port’s actual MAC address.

       fake_bridge: boolean
              Does this port represent a sub-bridge for its tagged VLAN within
              the Bridge? See ovs-vsctl(8) for more information.

       protected: boolean
              The protected ports feature allows certain ports  to  be  desig‐
              nated  as protected. Traffic between protected ports is blocked.
              Protected ports can send traffic to  unprotected  ports.  Unpro‐
              tected ports can send traffic to any port. Default is false.

       external_ids : fake-bridge-id-*: optional string
              External  IDs for a fake bridge (see the fake_bridge column) are
              defined  by   prefixing   a   Bridge   external_ids   key   with
              fake-bridge-, e.g. fake-bridge-xs-network-uuids.

       other_config : transient: optional string, either true or false
              If  set  to  true,  the  port will be removed when ovs-ctl start
              --delete-transient-ports is used.

       bond_active_slave: optional string
              For a bonded port, record the MAC address of the current  active
              member.

     Port Statistics:

       Key-value  pairs that report port statistics. The update period is con‐
       trolled by other_config:stats-update-interval in the  Open_vSwitch  ta‐
       ble.

     Statistics: STP transmit and receive counters:

       statistics : stp_tx_count: optional integer
              Number  of  STP  BPDUs  sent  on  this port by the spanning tree
              library.

       statistics : stp_rx_count: optional integer
              Number of STP BPDUs received on this port and  accepted  by  the
              spanning tree library.

       statistics : stp_error_count: optional integer
              Number of bad STP BPDUs received on this port. Bad BPDUs include
              runt packets and those with an unexpected protocol ID.

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Interface TABLE
       An interface within a Port.

   Summary:
       Core Features:
         name                        immutable  string  (must be unique within
                                     table)
         ifindex                     optional   integer,   in   range   0   to
                                     4,294,967,295
         mac_in_use                  optional string
         mac                         optional string
         error                       optional string
         OpenFlow Port Number:
            ofport                   optional integer
            ofport_request           optional integer, in range 1 to 65,279
       System-Specific Details:
         type                        string
       Tunnel Options:
         options : remote_ip         optional string
         options : local_ip          optional string
         options : in_key            optional string
         options : out_key           optional string
         options : dst_port          optional string
         options : key               optional string
         options : tos               optional string
         options : ttl               optional string
         options : df_default        optional string, either true or false
         options : egress_pkt_mark   optional string
         Tunnel Options: lisp only:
            options : packet_type    optional string, either legacy_l3 or ptap
         Tunnel Options: vxlan only:
            options : exts           optional string
            options : packet_type    optional   string,   one   of  legacy_l2,
                                     legacy_l3, or ptap
         Tunnel Options: gre only:
            options : packet_type    optional  string,   one   of   legacy_l2,
                                     legacy_l3, or ptap
            options : seq            optional string, either true or false
         Tunnel Options: gre, ip6gre, geneve, bareudp and vxlan:
            options : csum           optional string, either true or false
         Tunnel Options: IPsec:
            options : psk            optional string
            options : remote_cert    optional string
            options : remote_name    optional string
       Tunnel Options: erspan only:
         options : erspan_idx        optional string
         options : erspan_ver        optional string
         options : erspan_dir        optional string
         options : erspan_hwid       optional string
       Tunnel Options: Bareudp only:
         options : payload_type      optional string
       Patch Options:
         options : peer              optional string
       PMD (Poll Mode Driver) Options:
         options : n_rxq             optional  string,  containing an integer,
                                     at least 1
         options : dpdk-devargs      optional string
         other_config : pmd-rxq-affinity
                                     optional string
         options : xdp-mode          optional  string,  one  of   best-effort,
                                     generic, native-with-zerocopy, or native
         options : use-need-wakeup   optional string, either true or false
         options : vhost-server-path
                                     optional string
         options : tx-retries-max    optional  string,  containing an integer,
                                     in range 0 to 32
         options : n_rxq_desc        optional string, containing  an  integer,
                                     in range 1 to 4,096
         options : n_txq_desc        optional  string,  containing an integer,
                                     in range 1 to 4,096
         options : dpdk-vf-mac       optional string
       EMC (Exact Match Cache) Configuration:
         other_config : emc-enable   optional string, either true or false
       MTU:
         mtu                         optional integer
         mtu_request                 optional integer, at least 1
       Interface Status:
         admin_state                 optional string, either down or up
         link_state                  optional string, either down or up
         link_resets                 optional integer
         link_speed                  optional integer
         duplex                      optional string, either full or half
         lacp_current                optional boolean
         status                      map of string-string pairs
         status : driver_name        optional string
         status : driver_version     optional string
         status : firmware_version   optional string
         status : source_ip          optional string
         status : tunnel_egress_iface
                                     optional string
         status : tunnel_egress_iface_carrier
                                     optional string, either down or up
         dpdk:
            status : port_no         optional string
            status : numa_id         optional string
            status : min_rx_bufsize  optional string
            status : max_rx_pktlen   optional string
            status : max_rx_queues   optional string
            status : max_tx_queues   optional string
            status : max_mac_addrs   optional string
            status : max_hash_mac_addrs
                                     optional string
            status : max_vfs         optional string
            status : max_vmdq_pools  optional string
            status : if_type         optional string
            status : if_descr        optional string
            status : pci-vendor_id   optional string
            status : pci-device_id   optional string
       Statistics:
         Statistics: Successful transmit and receive counters:
            statistics : rx_packets  optional integer
            statistics : rx_bytes    optional integer
            statistics : tx_packets  optional integer
            statistics : tx_bytes    optional integer
         Statistics: Receive errors:
            statistics : rx_dropped  optional integer
            statistics : rx_frame_err
                                     optional integer
            statistics : rx_over_err optional integer
            statistics : rx_crc_err  optional integer
            statistics : rx_errors   optional integer
         Statistics: Transmit errors:
            statistics : tx_dropped  optional integer
            statistics : collisions  optional integer
            statistics : tx_errors   optional integer
       Ingress Policing:
         ingress_policing_rate       integer, at least 0
         ingress_policing_burst      integer, at least 0
       Bidirectional Forwarding Detection (BFD):
         BFD Configuration:
            bfd : enable             optional string, either true or false
            bfd : min_rx             optional string, containing  an  integer,
                                     at least 1
            bfd : min_tx             optional  string,  containing an integer,
                                     at least 1
            bfd : decay_min_rx       optional string, containing an integer
            bfd : forwarding_if_rx   optional string, either true or false
            bfd : cpath_down         optional string, either true or false
            bfd : check_tnl_key      optional string, either true or false
            bfd : bfd_local_src_mac  optional string
            bfd : bfd_local_dst_mac  optional string
            bfd : bfd_remote_dst_mac optional string
            bfd : bfd_src_ip         optional string
            bfd : bfd_dst_ip         optional string
            bfd : oam                optional string
            bfd : mult               optional string, containing  an  integer,
                                     in range 1 to 255
         BFD Status:
            bfd_status : state       optional string, one of admin_down, down,
                                     init, or up
            bfd_status : forwarding  optional string, either true or false
            bfd_status : diagnostic  optional string
            bfd_status : remote_state
                                     optional string, one of admin_down, down,
                                     init, or up
            bfd_status : remote_diagnostic
                                     optional string
            bfd_status : flap_count  optional  string,  containing an integer,
                                     at least 0
       Connectivity Fault Management:
         cfm_mpid                    optional integer
         cfm_flap_count              optional integer
         cfm_fault                   optional boolean
         cfm_fault_status : recv     none
         cfm_fault_status : rdi      none
         cfm_fault_status : maid     none
         cfm_fault_status : loopback
                                     none
         cfm_fault_status : overflow
                                     none
         cfm_fault_status : override
                                     none
         cfm_fault_status : interval
                                     none
         cfm_remote_opstate          optional string, either down or up
         cfm_health                  optional integer, in range 0 to 100
         cfm_remote_mpids            set of integers
         other_config : cfm_interval
                                     optional string, containing an integer
         other_config : cfm_extended
                                     optional string, either true or false
         other_config : cfm_demand   optional string, either true or false
         other_config : cfm_opstate  optional string, either down or up
         other_config : cfm_ccm_vlan
                                     optional string, containing  an  integer,
                                     in range 1 to 4,095
         other_config : cfm_ccm_pcp  optional  string,  containing an integer,
                                     in range 1 to 7
       Bonding Configuration:
         other_config : lacp-port-id
                                     optional string, containing  an  integer,
                                     in range 1 to 65,535
         other_config : lacp-port-priority
                                     optional  string,  containing an integer,
                                     in range 1 to 65,535
         other_config : lacp-aggregation-key
                                     optional string, containing  an  integer,
                                     in range 1 to 65,535
       Virtual Machine Identifiers:
         external_ids : attached-mac
                                     optional string
         external_ids : iface-id     optional string
         external_ids : iface-status
                                     optional  string,  either active or inac‐
                                     tive
         external_ids : xs-vif-uuid  optional string
         external_ids : xs-network-uuid
                                     optional string
         external_ids : vm-id        optional string
         external_ids : xs-vm-uuid   optional string
       Auto Attach Configuration:
         lldp : enable               optional string, either true or false
       Flow control Configuration:
         options : rx-flow-ctrl      optional string, either true or false
         options : tx-flow-ctrl      optional string, either true or false
         options : flow-ctrl-autoneg
                                     optional string, either true or false
       Link State Change detection mode:
         options : dpdk-lsc-interrupt
                                     optional string, either true or false
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
     Core Features:

       name: immutable string (must be unique within table)
              Interface name. Should be  alphanumeric.  For  non-bonded  port,
              this  should  be the same as the port name. It must otherwise be
              unique among the names of ports, interfaces, and  bridges  on  a
              host.

              The  maximum length of an interface name depends on the underly‐
              ing datapath:

              ·      The names of interfaces implemented as Linux and BSD net‐
                     work  devices,  including  interfaces with type internal,
                     tap, or system plus the different types of tunnel  ports,
                     are  limited  to  15 bytes. Windows limits these names to
                     255 bytes.

              ·      The names of patch ports are not used in  the  underlying
                     datapath,  so operating system restrictions do not apply.
                     Thus, they may have arbitrary length.

              Regardless of other restrictions, OpenFlow only supports 15-byte
              names,  which means that ovs-ofctl and OpenFlow controllers will
              show names truncated to 15 bytes.

       ifindex: optional integer, in range 0 to 4,294,967,295
              A positive interface index as defined for SNMP  MIB-II  in  RFCs
              1213  and  2863,  if  the  interface  has  one, otherwise 0. The
              ifindex is useful for seamless integration with  protocols  such
              as SNMP and sFlow.

       mac_in_use: optional string
              The MAC address in use by this interface.

       mac: optional string
              Ethernet  address  to  set for this interface. If unset then the
              default MAC address is used:

              ·      For the local interface, the default is  the  lowest-num‐
                     bered  MAC  address  among the other bridge ports, either
                     the value of the mac in its Port record, if set,  or  its
                     actual MAC (for bonded ports, the MAC of its member whose
                     name is first in alphabetical order). Internal ports  and
                     bridge ports that are used as port mirroring destinations
                     (see the Mirror table) are ignored.

              ·      For other internal interfaces, the default  MAC  is  ran‐
                     domly generated.

              ·      External  interfaces typically have a MAC address associ‐
                     ated with their hardware.

              Some  interfaces  may  not  have  a  software-controllable   MAC
              address. This option only affects internal ports. For other type
              ports, you can change the  MAC  address  outside  Open  vSwitch,
              using ip command.

       error: optional string
              If  the  configuration of the port failed, as indicated by -1 in
              ofport, Open vSwitch sets this column to an error description in
              human readable form. Otherwise, Open vSwitch clears this column.

     OpenFlow Port Number:

       When  a  client  adds a new interface, Open vSwitch chooses an OpenFlow
       port number for the new port. If the client that adds the port fills in
       ofport_request,  then  Open vSwitch tries to use its value as the Open‐
       Flow port number. Otherwise, or if the requested port number is already
       in use or cannot be used for another reason, Open vSwitch automatically
       assigns a free port number. Regardless  of  how  the  port  number  was
       obtained,  Open vSwitch then reports in ofport the port number actually
       assigned.

       Open vSwitch limits the port numbers that it automatically  assigns  to
       the  range 1 through 32,767, inclusive. Controllers therefore have free
       use of ports 32,768 and up.

       ofport: optional integer
              OpenFlow port number for this interface. Open vSwitch sets  this
              column’s value, so other clients should treat it as read-only.

              The  OpenFlow  ``local’’  port (OFPP_LOCAL) is 65,534. The other
              valid port numbers are in the  range  1  to  65,279,  inclusive.
              Value -1 indicates an error adding the interface.

       ofport_request: optional integer, in range 1 to 65,279
              Requested OpenFlow port number for this interface.

              A  client  should  ideally  set  this column’s value in the same
              database transaction that it uses to create the interface.  Open
              vSwitch  version  2.1 and later will honor a later request for a
              specific port  number,  althuogh  it  might  confuse  some  con‐
              trollers: OpenFlow does not have a way to announce a port number
              change, so Open vSwitch represents it over OpenFlow  as  a  port
              deletion followed immediately by a port addition.

              If  ofport_request  is set or changed to some other port’s auto‐
              matically assigned port number, Open vSwitch chooses a new  port
              number for the latter port.

     System-Specific Details:

       type: string
              The interface type. The types supported by a particular instance
              of Open vSwitch are listed in  the  iface_types  column  in  the
              Open_vSwitch table. The following types are defined:

              system An ordinary network device, e.g. eth0 on Linux. Sometimes
                     referred to as ``external  interfaces’’  since  they  are
                     generally connected to hardware external to that on which
                     the Open vSwitch is running. The empty string is  a  syn‐
                     onym for system.

              internal
                     A  simulated network device that sends and receives traf‐
                     fic. An internal interface whose name is the same as  its
                     bridge’s  name is called the ``local interface.’’ It does
                     not make sense to bond  an  internal  interface,  so  the
                     terms  ``port’’  and  ``interface’’ are often used impre‐
                     cisely for internal interfaces.

              tap    A TUN/TAP device managed by Open vSwitch.

                     Open vSwitch checks the interface state before send pack‐
                     ets  to  the  device.  When  it  is down, the packets are
                     dropped and the tx_dropped statistic is  updated  accord‐
                     ingly.  Older  versions of Open vSwitch did not check the
                     interface state and then the tx_packets  was  incremented
                     along with tx_dropped.

              geneve An             Ethernet            over            Geneve
                     (http://tools.ietf.org/html/draft-ietf-nvo3-geneve)
                     IPv4/IPv6  tunnel.  A description of how to match and set
                     Geneve options can be found in the ovs-ofctl manual page.

              gre    Generic Routing Encapsulation  (GRE)  over  IPv4  tunnel,
                     configurable to encapsulate layer 2 or layer 3 traffic.

              ip6gre Generic  Routing  Encapsulation  (GRE)  over IPv6 tunnel,
                     encapsulate layer 2 traffic.

              vxlan  An Ethernet tunnel  over  the  UDP-based  VXLAN  protocol
                     described in RFC 7348.

                     Open  vSwitch  uses  IANA-assigned  UDP  destination port
                     4789. The source port used for VXLAN traffic varies on  a
                     per-flow basis and is in the ephemeral port range.

              lisp   A  layer  3 tunnel over the experimental, UDP-based Loca‐
                     tor/ID Separation Protocol (RFC 6830).

                     Only IPv4 and IPv6 packets are supported by the protocol,
                     and  they  are  sent  and  received  without  an Ethernet
                     header. Traffic to/from LISP ports is expected to be con‐
                     figured  explicitly,  and  the  ports are not intended to
                     participate in learning based switching.  As  such,  they
                     are always excluded from packet flooding.

              stt    The  Stateless  TCP  Tunnel  (STT) is particularly useful
                     when tunnel endpoints are in end-systems, as it  utilizes
                     the  capabilities  of standard network interface cards to
                     improve  performance.  STT  utilizes  a  TCP-like  header
                     inside  the IP header. It is stateless, i.e., there is no
                     TCP connection state of any kind associated with the tun‐
                     nel. The TCP-like header is used to leverage the capabil‐
                     ities of existing network interface cards, but should not
                     be  interpreted  as implying any sort of connection state
                     between endpoints. Since the STT protocol does not engage
                     in  the usual TCP 3-way handshake, so it will have diffi‐
                     culty traversing stateful firewalls. The protocol is doc‐
                     umented   at  https://tools.ietf.org/html/draft-davie-stt
                     All traffic uses a default destination port of 7471.

              patch  A pair of virtual devices that act as a patch cable.

              gtpu   GPRS Tunneling Protocol (GTP) is a group of IP-based com‐
                     munications  protocols used to carry general packet radio
                     service (GPRS) within GSM, UMTS and LTE  networks.  GTP-U
                     is  used for carrying user data within the GPRS core net‐
                     work and between the radio access network  and  the  core
                     network.  The user data transported can be packets in any
                     of IPv4, IPv6, or PPP formats.

                     The protocol is documented at http://www.3gpp.org/DynaRe‐
                     port/29281.htm

                     Open  vSwitch  uses UDP destination port 2152. The source
                     port used for GTP traffic varies on a per-flow basis  and
                     is in the ephemeral port range.

              Bareudp
                     The  Bareudp  tunnel  provides a generic L3 encapsulation
                     support for tunnelling different L3 protocols like  MPLS,
                     IP, NSH etc. inside a UDP tunnel.

     Tunnel Options:

       These  options  apply  to interfaces with type of geneve, bareudp, gre,
       ip6gre, vxlan, lisp and stt.

       Each tunnel must be uniquely identified by  the  combination  of  type,
       options:remote_ip,  options:local_ip,  and options:in_key. If two ports
       are defined that are the same except one has an optional identifier and
       the   other   does  not,  the  more  specific  one  is  matched  first.
       options:in_key is considered more specific than options:local_ip  if  a
       port  defines one and another port defines the other. options:in_key is
       not applicable for bareudp tunnels. Hence it is  not  considered  while
       identifying a bareudp tunnel.

       options : remote_ip: optional string
              Required. The remote tunnel endpoint, one of:

              ·      An   IPv4   or  IPv6  address  (not  a  DNS  name),  e.g.
                     192.168.0.123. Only unicast endpoints are supported.

              ·      The word flow. The tunnel accepts packets from any remote
                     tunnel  endpoint. To process only packets from a specific
                     remote tunnel endpoint, the flow entries may match on the
                     tun_src  or  tun_ipv6_srcfield. When sending packets to a
                     remote_ip=flow tunnel, the flow actions  must  explicitly
                     set  the  tun_dst or tun_ipv6_dst field to the IP address
                     of the  desired  remote  tunnel  endpoint,  e.g.  with  a
                     set_field action.

              The remote tunnel endpoint for any packet received from a tunnel
              is available in the tun_src field for matching in the  flow  ta‐
              ble.

       options : local_ip: optional string
              Optional.  The  tunnel destination IP that received packets must
              match. Default is to match all addresses. If specified,  may  be
              one of:

              ·      An IPv4/IPv6 address (not a DNS name), e.g. 192.168.12.3.

              ·      The  word flow. The tunnel accepts packets sent to any of
                     the local IP addresses of  the  system  running  OVS.  To
                     process  only  packets sent to a specific IP address, the
                     flow entries may match on  the  tun_dst  or  tun_ipv6_dst
                     field.  When  sending  packets to a local_ip=flow tunnel,
                     the flow  actions  may  explicitly  set  the  tun_src  or
                     tun_ipv6_src field to the desired IP address, e.g. with a
                     set_field action. However,  while  routing  the  tunneled
                     packet  out,  the local system may override the specified
                     address with the local IP address configured for the out‐
                     going system interface.

                     This  option  is  valid  only for tunnels also configured
                     with the remote_ip=flow option.

              The tunnel destination IP address for any packet received from a
              tunnel  is  available  in  the tun_dst or tun_ipv6_dst field for
              matching in the flow table.

       options : in_key: optional string
              Optional, not applicable for  bareudp.  The  key  that  received
              packets must contain, one of:

              ·      0.  The tunnel receives packets with no key or with a key
                     of 0. This is equivalent to specifying no  options:in_key
                     at all.

              ·      A  positive  24-bit (for Geneve, VXLAN, and LISP), 32-bit
                     (for GRE) or 64-bit (for STT) number. The tunnel receives
                     only packets with the specified key.

              ·      The  word  flow. The tunnel accepts packets with any key.
                     The key will be placed in the tun_id field  for  matching
                     in the flow table. The ovs-fields(7) manual page contains
                     additional information about matching fields in  OpenFlow
                     flows.

       options : out_key: optional string
              Optional,  not applicable for bareudp. The key to be set on out‐
              going packets, one of:

              ·      0. Packets sent through the tunnel will have no key. This
                     is equivalent to specifying no options:out_key at all.

              ·      A  positive  24-bit  (for Geneve, VXLAN and LISP), 32-bit
                     (for GRE)  or  64-bit  (for  STT)  number.  Packets  sent
                     through the tunnel will have the specified key.

              ·      The  word flow. Packets sent through the tunnel will have
                     the key set using the set_tunnel Nicira  OpenFlow  vendor
                     extension  (0  is  used in the absence of an action). The
                     ovs-fields(7) manual page contains additional information
                     about the Nicira OpenFlow vendor extensions.

       options : dst_port: optional string
              Optional.  The  tunnel transport layer destination port, for UDP
              and TCP based tunnel protocols (Geneve, VXLAN, LISP, and STT).

       options : key: optional string
              Optional. Shorthand to set in_key and out_key at the same time.

       options : tos: optional string
              Optional. The value of the ToS bits to be set on the encapsulat‐
              ing  packet.  ToS  is interpreted as DSCP and ECN bits, ECN part
              must be zero. It may also be the word inherit, in which case the
              ToS  will  be copied from the inner packet if it is IPv4 or IPv6
              (otherwise it will be 0). The ECN fields are  always  inherited.
              Default is 0.

       options : ttl: optional string
              Optional.  The TTL to be set on the encapsulating packet. It may
              also be the word inherit, in which case the TTL will  be  copied
              from  the  inner packet if it is IPv4 or IPv6 (otherwise it will
              be the system default, typically  64).  Default  is  the  system
              default TTL.

       options : df_default: optional string, either true or false
              Optional. If enabled, the Don’t Fragment bit will be set on tun‐
              nel outer headers  to  allow  path  MTU  discovery.  Default  is
              enabled; set to false to disable.

       options : egress_pkt_mark: optional string
              Optional.  The  pkt_mark  to be set on the encapsulating packet.
              This option sets packet mark for the  tunnel  endpoint  for  all
              tunnel packets including tunnel monitoring.

     Tunnel Options: lisp only:

       options : packet_type: optional string, either legacy_l3 or ptap
              A  LISP  tunnel  sends  and receives only IPv4 and IPv6 packets.
              This option controls what how the tunnel represents the  packets
              that it sends and receives:

              ·      By  default,  or  if this option is legacy_l3, the tunnel
                     represents packets as Ethernet frames  for  compatibility
                     with  legacy OpenFlow controllers that expect this behav‐
                     ior.

              ·      If this option is ptap,  the  tunnel  represents  packets
                     using  the  packet_type  mechanism introduced in OpenFlow
                     1.5.

     Tunnel Options: vxlan only:

       options : exts: optional string
              Optional. Comma separated list of optional VXLAN  extensions  to
              enable. The following extensions are supported:

              ·      gbp:  VXLAN-GBP allows to transport the group policy con‐
                     text of a packet across the VXLAN tunnel to other network
                     peers.    See   the   description   of   tun_gbp_id   and
                     tun_gbp_flags in ovs-fields(7)  for  additional  informa‐
                     tion.
                     (https://tools.ietf.org/html/draft-smith-vxlan-group-pol‐
                     icy)

              ·      gpe: Support for Generic Protocol Encapsulation in accor‐
                     dance             with             IETF             draft
                     https://tools.ietf.org/html/draft-ietf-nvo3-vxlan-gpe.
                     Without this option, a VXLAN packet  always  encapsulates
                     an  Ethernet frame. With this option, an VXLAN packet may
                     also encapsulate an IPv4, IPv6, NSH, or MPLS packet.

       options : packet_type: optional string, one of legacy_l2, legacy_l3, or
       ptap
              This  option controls what types of packets the tunnel sends and
              receives and how it represents them:

              ·      By default, or if this option is  legacy_l2,  the  tunnel
                     sends and receives only Ethernet frames.

              ·      If  this  option  is  legacy_l3,  the  tunnel  sends  and
                     receives only non-Ethernet (L3) packet, but  the  packets
                     are represented as Ethernet frames for compatibility with
                     legacy OpenFlow controllers that  expect  this  behavior.
                     This requires enabling gpe in options:exts.

              ·      If  this  option is ptap, Open vSwitch represents packets
                     in the tunnel using the packet_type mechanism  introduced
                     in  OpenFlow  1.5.  This  mechanism  supports any kind of
                     packet, but actually sending and  receiving  non-Ethernet
                     packets    requires    additionally   enabling   gpe   in
                     options:exts.

     Tunnel Options: gre only:

       gre interfaces support these options.

       options : packet_type: optional string, one of legacy_l2, legacy_l3, or
       ptap
              This  option controls what types of packets the tunnel sends and
              receives and how it represents them:

              ·      By default, or if this option is  legacy_l2,  the  tunnel
                     sends and receives only Ethernet frames.

              ·      If  this  option  is  legacy_l3,  the  tunnel  sends  and
                     receives only non-Ethernet (L3) packet, but  the  packets
                     are represented as Ethernet frames for compatibility with
                     legacy OpenFlow controllers that expect this behavior.

              ·      The legacy_l3 option is only available via the user space
                     datapath.  The  OVS  kernel  datapath  does  not  support
                     devices of type ARPHRD_IPGRE which is the requirement for
                     legacy_l3 type packets.

              ·      If this option is ptap, the tunnel sends and receives any
                     kind of packet. Open vSwitch represents  packets  in  the
                     tunnel  using  the  packet_type  mechanism  introduced in
                     OpenFlow 1.5.

       options : seq: optional string, either true or false
              Optional. A 4-byte sequence number field for  GRE  tunnel  only.
              Default  is  disabled, set to true to enable. Sequence number is
              incremented by one on each outgoing packet.

     Tunnel Options: gre, ip6gre, geneve, bareudp and vxlan:

       gre,  ip6gre,  geneve,  bareudp  and  vxlan  interfaces  support  these
       options.

       options : csum: optional string, either true or false
              Optional.  Compute  encapsulation  header  (either  GRE  or UDP)
              checksums on outgoing packets. Default is disabled, set to  true
              to  enable.  Checksums present on incoming packets will be vali‐
              dated regardless of this setting.

              When using the upstream  Linux  kernel  module,  computation  of
              checksums for geneve and vxlan requires Linux kernel version 4.0
              or higher. gre and ip6gre support checksums for all versions  of
              Open  vSwitch  that  support  GRE. The out of tree kernel module
              distributed as part of OVS can compute all tunnel  checksums  on
              any kernel version that it is compatible with.

     Tunnel Options: IPsec:

       Setting  any of these options enables IPsec support for a given tunnel.
       gre, geneve, vxlan and stt interfaces support these  options.  See  the
       IPsec section in the Open_vSwitch table for a description of each mode.

       options : psk: optional string
              In PSK mode only, the preshared secret to negotiate tunnel. This
              value must match on both tunnel ends.

       options : remote_cert: optional string
              In self-signed certificate mode only, name of a  PEM  file  con‐
              taining a certificate of the remote switch. The certificate must
              be x.509 version 3 and with the string in common name (CN)  also
              set in the subject alternative name (SAN).

       options : remote_name: optional string
              In  CA-signed  certificate  mode  only,  common name (CN) of the
              remote certificate.

     Tunnel Options: erspan only:

       Only erspan interfaces support these options.

       options : erspan_idx: optional string
              20 bit index/port number associated with  the  ERSPAN  traffic’s
              source  port and direction (ingress/egress). This field is plat‐
              form dependent.

       options : erspan_ver: optional string
              ERSPAN version: 1 for version 1 (type II) or  2  for  version  2
              (type III).

       options : erspan_dir: optional string
              Specifies  the  ERSPAN  v2  mirrored  traffic’s direction. 1 for
              egress traffic, and 0 for ingress traffic.

       options : erspan_hwid: optional string
              ERSPAN hardware ID is a 6-bit unique identifier of an ERSPAN  v2
              engine within a system.

     Tunnel Options: Bareudp only:

       options : payload_type: optional string
              Specifies the ethertype of the l3 protocol the bareudp device is
              tunnelling. For the tunnels which supports  multiple  ethertypes
              of  a  l3  protocol (IP, MPLS) this field specifies the protocol
              name as a string.

     Patch Options:

       These options apply only to patch ports, that is, interfaces whose type
       column  is  patch.  Patch  ports  are mainly a way to connect otherwise
       independent bridges to one another, similar to how one  might  plug  an
       Ethernet  cable  (a ``patch cable’’) into two physical switches to con‐
       nect those switches. The effect of  plugging  a  patch  port  into  two
       switches  is conceptually similar to that of plugging the two ends of a
       Linux veth device into those switches, but the implementation of  patch
       ports makes them much more efficient.

       Patch  ports  may connect two different bridges (the usual case) or the
       same bridge. In the latter case, take special care to avoid loops, e.g.
       by programming appropriate flows with OpenFlow. Patch ports do not work
       if its ends are attached to bridges on  different  datapaths,  e.g.  to
       connect bridges in system and netdev datapaths.

       The  following  command  creates and connects patch ports p0 and p1 and
       adds them to bridges br0 and br1, respectively:

       ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \
              -- add-port br1 p1 -- set Interface p1 type=patch options:peer=p0


       options : peer: optional string
              The name of the Interface for the other side of the  patch.  The
              named  Interface’s own peer option must specify this Interface’s
              name. That is, the two patch interfaces must have reversed  name
              and peer values.

     PMD (Poll Mode Driver) Options:

       Only PMD netdevs support these options.

       options : n_rxq: optional string, containing an integer, at least 1
              Specifies  the maximum number of rx queues to be created for PMD
              netdev. If not specified or specified to 0, one rx queue will be
              created by default. Not supported by DPDK vHost interfaces.

       options : dpdk-devargs: optional string
              Specifies  the PCI address associated with the port for physical
              devices, or the virtual driver to be used for the  port  when  a
              virtual PMD is intended to be used. For the latter, the argument
              string typically  takes  the  form  of  eth_driver_namex,  where
              driver_name  is  a valid virtual DPDK PMD driver name and x is a
              unique identifier of your choice for the given port.  Only  sup‐
              ported by the dpdk port type.

       other_config : pmd-rxq-affinity: optional string
              Specifies mapping of RX queues of this interface to CPU cores.

              Value should be set in the following form:

              other_config:pmd-rxq-affinity=<rxq-affinity-list>

              where

              ·      <rxq-affinity-list> ::= NULL | <non-empty-list>

              ·      <non-empty-list>  ::= <affinity-pair> | <affinity-pair> ,
                     <non-empty-list>

              ·      <affinity-pair> ::= <queue-id> : <core-id>

       options : xdp-mode:  optional  string,  one  of  best-effort,  generic,
       native-with-zerocopy, or native
              Specifies the operational mode of the XDP program.

              In  native-with-zerocopy mode the XDP program is loaded into the
              device driver with  zero-copy  RX  and  TX  enabled.  This  mode
              requires  device  driver  support  and  has the best performance
              because there should be no copying of packets.

              native is the same as native-with-zerocopy,  but  without  zero-
              copy  capability. This requires at least one copy between kernel
              and the userspace. This mode also requires support  from  device
              driver.

              In  generic case the XDP program in kernel works after skb allo‐
              cation on early stages of packet processing inside  the  network
              stack.  This  mode  doesn’t require driver support, but has much
              lower performance.

              best-effort tries to detect and choose the best  (fastest)  from
              the available modes for current interface.

              Note  that  this option is specific to netdev-afxdp. Defaults to
              best-effort mode.

       options : use-need-wakeup: optional string, either true or false
              Specifies whether to use need_wakeup feature in afxdp netdev. If
              enabled,  OVS  explicitly  wakes  up the kernel RX, using poll()
              syscall and wakes up TX, using sendto()  syscall.  For  physical
              devices,  this  feature  improves  the  performance  by avoiding
              unnecessary sendto syscalls. Defaults to true  if  supported  by
              libbpf.

       options : vhost-server-path: optional string
              The  value  specifies  the  path to the socket associated with a
              vHost User client mode device that has been or will  be  created
              by QEMU. Only supported by dpdkvhostuserclient interfaces.

       options  :  tx-retries-max:  optional string, containing an integer, in
       range 0 to 32
              The value specifies the maximum amount of vhost tx retries  that
              can be made while trying to send a batch of packets to an inter‐
              face. Only supported by dpdkvhostuserclient interfaces.

              Default value is 8.

       options : n_rxq_desc: optional string, containing an integer, in  range
       1 to 4,096
              Specifies  the  rx  queue  size (number rx descriptors) for dpdk
              ports. The value must be a power of 2, less than 4096  and  sup‐
              ported  by  the  hardware of the device being configured. If not
              specified or an incorrect value is specified, 2048  rx  descrip‐
              tors will be used by default.

       options  : n_txq_desc: optional string, containing an integer, in range
       1 to 4,096
              Specifies the tx queue size (number  tx  descriptors)  for  dpdk
              ports.  The  value must be a power of 2, less than 4096 and sup‐
              ported by the hardware of the device being  configured.  If  not
              specified  or  an incorrect value is specified, 2048 tx descrip‐
              tors will be used by default.

       options : dpdk-vf-mac: optional string
              Ethernet address to set for this VF interface. If unset then the
              default MAC address is used:

              ·      For  most  drivers,  the  default MAC address assigned by
                     their hardware.

              ·      For bifurcated drivers, the MAC  currently  used  by  the
                     kernel netdevice.

              This option may only be used with dpdk VF representors.

     EMC (Exact Match Cache) Configuration:

       These settings controls behaviour of EMC lookups/insertions for packets
       received from the interface.

       other_config : emc-enable: optional string, either true or false
              Specifies if Exact Match Cache (EMC) should be used  while  pro‐
              cessing   packets   received   from  this  interface.  If  true,
              other_config:emc-insert-inv-prob will have effect on this inter‐
              face.

              Defaults to true.

     MTU:

       The  MTU (maximum transmission unit) is the largest amount of data that
       can fit into a single Ethernet frame. The standard Ethernet MTU is 1500
       bytes.  Some physical media and many kinds of virtual interfaces can be
       configured with higher MTUs.

       A client may change an interface MTU by filling  in  mtu_request.  Open
       vSwitch then reports in mtu the currently configured value.

       mtu: optional integer
              The currently configured MTU for the interface.

              This column will be empty for an interface that does not have an
              MTU as, for example, some kinds of tunnels do not.

              Open vSwitch sets this column’s value, so other  clients  should
              treat it as read-only.

       mtu_request: optional integer, at least 1
              Requested  MTU  (Maximum Transmission Unit) for the interface. A
              client can fill this column to change the MTU of an interface.

              RFC 791 requires every internet module to be able to  forward  a
              datagram of 68 octets without further fragmentation. The maximum
              size of an IP packet is 65535 bytes.

              If this is not set and if the interface has internal type,  Open
              vSwitch  will  change  the MTU to match the minimum of the other
              interfaces in the bridge.

     Interface Status:

       Status information about interfaces attached to bridges, updated  every
       5  seconds.  Not  all  interfaces have all of these properties; virtual
       interfaces don’t have a link speed, for example. Non-applicable columns
       will have empty values.

       admin_state: optional string, either down or up
              The administrative state of the physical network link.

       link_state: optional string, either down or up
              The  observed  state of the physical network link. This is ordi‐
              narily the link’s carrier status. If the interface’s Port  is  a
              bond configured for miimon monitoring, it is instead the network
              link’s miimon status.

       link_resets: optional integer
              The number of times Open vSwitch has observed the link_state  of
              this Interface change.

       link_speed: optional integer
              The  negotiated speed of the physical network link. Valid values
              are positive integers greater than 0.

       duplex: optional string, either full or half
              The duplex mode of the physical network link.

       lacp_current: optional boolean
              Boolean value indicating LACP  status  for  this  interface.  If
              true, this interface has current LACP information about its LACP
              partner. This information may be used to monitor the  health  of
              interfaces  in a LACP enabled port. This column will be empty if
              LACP is not enabled.

       status: map of string-string pairs
              Key-value pairs that report port status. Supported status values
              are  type-dependent;  some  interfaces may not have a valid sta‐
              tus:driver_name, for example.

       status : driver_name: optional string
              The name of the device driver controlling the network adapter.

       status : driver_version: optional string
              The version string of the device driver controlling the  network
              adapter.

       status : firmware_version: optional string
              The  version string of the network adapter’s firmware, if avail‐
              able.

       status : source_ip: optional string
              The source IP address used for an  IPv4/IPv6  tunnel  end-point,
              such as gre.

       status : tunnel_egress_iface: optional string
              Egress  interface  for tunnels. Currently only relevant for tun‐
              nels on Linux systems, this column will show  the  name  of  the
              interface  which is responsible for routing traffic destined for
              the configured options:remote_ip.  This  could  be  an  internal
              interface such as a bridge port.

       status  :  tunnel_egress_iface_carrier: optional string, either down or
       up
              Whether carrier is detected on status:tunnel_egress_iface.

     dpdk:

       DPDK specific interface status options.

       status : port_no: optional string
              DPDK port ID.

       status : numa_id: optional string
              NUMA socket ID to which an Ethernet device is connected.

       status : min_rx_bufsize: optional string
              Minimum size of RX buffer.

       status : max_rx_pktlen: optional string
              Maximum configurable length of RX pkt.

       status : max_rx_queues: optional string
              Maximum number of RX queues.

       status : max_tx_queues: optional string
              Maximum number of TX queues.

       status : max_mac_addrs: optional string
              Maximum number of MAC addresses.

       status : max_hash_mac_addrs: optional string
              Maximum number of hash MAC addresses for MTA and UTA.

       status : max_vfs: optional string
              Maximum number of hash MAC addresses for MTA  and  UTA.  Maximum
              number of VFs.

       status : max_vmdq_pools: optional string
              Maximum number of VMDq pools.

       status : if_type: optional string
              Interface type ID according to IANA ifTYPE MIB definitions.

       status : if_descr: optional string
              Interface description string.

       status : pci-vendor_id: optional string
              Vendor ID of PCI device.

       status : pci-device_id: optional string
              Device ID of PCI device.

     Statistics:

       Key-value pairs that report interface statistics. The current implemen‐
       tation updates these counters periodically. The update period  is  con‐
       trolled  by  other_config:stats-update-interval in the Open_vSwitch ta‐
       ble. Future implementations may update them when an interface  is  cre‐
       ated, when they are queried (e.g. using an OVSDB select operation), and
       just before an interface is deleted due to virtual interface hot-unplug
       or  VM  shutdown,  and  perhaps  at other times, but not on any regular
       periodic basis.

       These are the same  statistics  reported  by  OpenFlow  in  its  struct
       ofp_port_stats  structure.  If  an  interface  does not support a given
       statistic, then that pair is omitted.

     Statistics: Successful transmit and receive counters:

       statistics : rx_packets: optional integer
              Number of received packets.

       statistics : rx_bytes: optional integer
              Number of received bytes.

       statistics : tx_packets: optional integer
              Number of transmitted packets.

       statistics : tx_bytes: optional integer
              Number of transmitted bytes.

     Statistics: Receive errors:

       statistics : rx_dropped: optional integer
              Number of packets dropped by RX.

       statistics : rx_frame_err: optional integer
              Number of frame alignment errors.

       statistics : rx_over_err: optional integer
              Number of packets with RX overrun.

       statistics : rx_crc_err: optional integer
              Number of CRC errors.

       statistics : rx_errors: optional integer
              Total number of receive errors, greater than or equal to the sum
              of the above.

     Statistics: Transmit errors:

       statistics : tx_dropped: optional integer
              Number of packets dropped by TX.

       statistics : collisions: optional integer
              Number of collisions.

       statistics : tx_errors: optional integer
              Total  number  of  transmit errors, greater than or equal to the
              sum of the above.

     Ingress Policing:

       These settings control ingress policing for packets  received  on  this
       interface. On a physical interface, this limits the rate at which traf‐
       fic is allowed into the system from the outside; on a virtual interface
       (one connected to a virtual machine), this limits the rate at which the
       VM is able to transmit.

       Policing is a simple form of quality-of-service that simply drops pack‐
       ets  received  in excess of the configured rate. Due to its simplicity,
       policing is usually less accurate and less effective  than  egress  QoS
       (which is configured using the QoS and Queue tables).

       Policing  is  currently  implemented  on  Linux and OVS with DPDK. Both
       implementations use a simple ``token bucket’’ approach:

              ·      The size of  the  bucket  corresponds  to  ingress_polic‐
                     ing_burst. Initially the bucket is full.

              ·      Whenever  a  packet  is  received, its size (converted to
                     tokens) is compared to the number of tokens currently  in
                     the  bucket.  If the required number of tokens are avail‐
                     able, they are removed and the packet is forwarded.  Oth‐
                     erwise, the packet is dropped.

              ·      Whenever  it  is  not  full,  the bucket is refilled with
                     tokens at the rate specified by ingress_policing_rate.

       Policing interacts badly with some network  protocols,  and  especially
       with fragmented IP packets. Suppose that there is enough network activ‐
       ity to keep the bucket nearly empty  all  the  time.  Then  this  token
       bucket  algorithm will forward a single packet every so often, with the
       period depending on packet size and on the configured rate. All of  the
       fragments  of an IP packets are normally transmitted back-to-back, as a
       group. In such a situation, therefore, only one of these fragments will
       be  forwarded and the rest will be dropped. IP does not provide any way
       for the intended recipient to ask for only the remaining fragments.  In
       such  a  case  there  are two likely possibilities for what will happen
       next: either all of the fragments will eventually be retransmitted  (as
       TCP  will do), in which case the same problem will recur, or the sender
       will not realize that its packet has been dropped and data will  simply
       be lost (as some UDP-based protocols will do). Either way, it is possi‐
       ble that no forward progress will ever occur.

       ingress_policing_rate: integer, at least 0
              Maximum rate for data received on this interface, in kbps.  Data
              received  faster  than  this  rate  is  dropped.  Set  to 0 (the
              default) to disable policing.

       ingress_policing_burst: integer, at least 0
              Maximum burst size for data received on this interface,  in  kb.
              The  default burst size if set to 0 is 8000 kbit. This value has
              no effect if ingress_policing_rate is 0.

              Specifying a larger burst size lets the algorithm be  more  for‐
              giving, which is important for protocols like TCP that react se‐
              verely to dropped packets. The burst size should be at least the
              size  of the interface’s MTU. Specifying a value that is numeri‐
              cally at least as large as 80%  of  ingress_policing_rate  helps
              TCP come closer to achieving the full rate.

     Bidirectional Forwarding Detection (BFD):

       BFD,  defined in RFC 5880 and RFC 5881, allows point-to-point detection
       of connectivity failures by occasional transmission of BFD control mes‐
       sages. Open vSwitch implements BFD to serve as a more popular and stan‐
       dards compliant alternative to CFM.

       BFD operates by regularly transmitting BFD control messages at  a  rate
       negotiated independently in each direction. Each endpoint specifies the
       rate at which it expects to receive control messages, and the  rate  at
       which  it  is willing to transmit them. By default, Open vSwitch uses a
       detection multiplier of three, meaning that an endpoint signals a  con‐
       nectivity  fault  if  three  consecutive  BFD  control messages fail to
       arrive. In the case of a unidirectional connectivity issue, the  system
       not  receiving  BFD control messages signals the problem to its peer in
       the messages it transmits.

       The Open vSwitch implementation of BFD aims to comply  faithfully  with
       RFC  5880  requirements.  Open  vSwitch does not implement the optional
       Authentication or ``Echo Mode’’ features.

       OVS 2.13 and earlier intercepted and processed  all  BFD  packets.  OVS
       2.14  and  later  only  intercept and process BFD packets destined to a
       configured BFD instance, and other BFD packets are  made  available  to
       the OVS flow table for forwarding.

     BFD Configuration:

       A  controller  sets  up key-value pairs in the bfd column to enable and
       configure BFD.

       bfd : enable: optional string, either true or false
              True to enable BFD on this Interface. If not specified, BFD will
              not be enabled by default.

       bfd : min_rx: optional string, containing an integer, at least 1
              The  shortest  interval, in milliseconds, at which this BFD ses‐
              sion offers to receive BFD control messages. The remote endpoint
              may choose to send messages at a slower rate. Defaults to 1000.

       bfd : min_tx: optional string, containing an integer, at least 1
              The  shortest  interval, in milliseconds, at which this BFD ses‐
              sion is willing to transmit BFD control messages. Messages  will
              actually  be transmitted at a slower rate if the remote endpoint
              is not willing to receive as quickly as specified.  Defaults  to
              100.

       bfd : decay_min_rx: optional string, containing an integer
              An  alternate  receive  interval,  in milliseconds, that must be
              greater than or equal to bfd:min_rx. The implementation switches
              from  bfd:min_rx  to  bfd:decay_min_rx  when there is no obvious
              incoming data traffic at the interface, to reduce  the  CPU  and
              bandwidth cost of monitoring an idle interface. This feature may
              be disabled by setting a value of 0. This feature is reset when‐
              ever bfd:decay_min_rx or bfd:min_rx changes.

       bfd : forwarding_if_rx: optional string, either true or false
              When true, traffic received on the Interface is used to indicate
              the capability of packet I/O.  BFD  control  packets  are  still
              transmitted  and  received. At least one BFD control packet must
              be received every 100 * bfd:min_rx amount  of  time.  Otherwise,
              even if traffic are received, the bfd:forwarding will be false.

       bfd : cpath_down: optional string, either true or false
              Set  to  true  to notify the remote endpoint that traffic should
              not be forwarded to this system for some  reason  other  than  a
              connectivty  failure on the interface being monitored. The typi‐
              cal underlying reason is ``concatenated path  down,’’  that  is,
              that  connectivity  beyond the local system is down. Defaults to
              false.

       bfd : check_tnl_key: optional string, either true or false
              Set to true to make BFD accept only control messages with a tun‐
              nel  key  of zero. By default, BFD accepts control messages with
              any tunnel key.

       bfd : bfd_local_src_mac: optional string
              Set to an Ethernet address in the form xx:xx:xx:xx:xx:xx to  set
              the  MAC used as source for transmitted BFD packets. The default
              is the mac address of the BFD enabled interface.

       bfd : bfd_local_dst_mac: optional string
              Set to an Ethernet address in the form xx:xx:xx:xx:xx:xx to  set
              the  MAC  used  as  destination for transmitted BFD packets. The
              default is 00:23:20:00:00:01.

       bfd : bfd_remote_dst_mac: optional string
              Set to an Ethernet address in the form xx:xx:xx:xx:xx:xx to  set
              the  MAC used for checking the destination of received BFD pack‐
              ets. Packets with different destination MAC will not be  consid‐
              ered  as  BFD  packets.  If  not  specified  the destination MAC
              address of received BFD packets are not checked.

       bfd : bfd_src_ip: optional string
              Set to an IPv4 address to set the IP address used as source  for
              transmitted BFD packets. The default is 169.254.1.1.

       bfd : bfd_dst_ip: optional string
              Set to an IPv4 address to set the IP address used as destination
              for transmitted BFD packets. The default is 169.254.1.0.

       bfd : oam: optional string
              Some tunnel protocols (such as Geneve)  include  a  bit  in  the
              header to indicate that the encapsulated packet is an OAM frame.
              By setting this to true, BFD packets will be marked  as  OAM  if
              encapsulated in one of these tunnels.

       bfd : mult: optional string, containing an integer, in range 1 to 255
              The  BFD  detection multiplier, which defaults to 3. An endpoint
              signals a connectivity fault if the given number of  consecutive
              BFD control messages fail to arrive.

     BFD Status:

       The  switch sets key-value pairs in the bfd_status column to report the
       status of BFD  on  this  interface.  When  BFD  is  not  enabled,  with
       bfd:enable, the switch clears all key-value pairs from bfd_status.

       bfd_status  : state: optional string, one of admin_down, down, init, or
       up
              Reports the state of the BFD session. The BFD session  is  fully
              healthy and negotiated if UP.

       bfd_status : forwarding: optional string, either true or false
              Reports  whether  the BFD session believes this Interface may be
              used to forward traffic. Typically this means the local  session
              is signaling UP, and the remote system isn’t signaling a problem
              such as concatenated path down.

       bfd_status : diagnostic: optional string
              A diagnostic code specifying the local system’s reason  for  the
              last  change in session state. The error messages are defined in
              section 4.1 of [RFC 5880].

       bfd_status : remote_state: optional string, one  of  admin_down,  down,
       init, or up
              Reports the state of the remote endpoint’s BFD session.

       bfd_status : remote_diagnostic: optional string
              A  diagnostic code specifying the remote system’s reason for the
              last change in session state. The error messages are defined  in
              section 4.1 of [RFC 5880].

       bfd_status  :  flap_count:  optional  string, containing an integer, at
       least 0
              Counts the number of bfd_status:forwarding flaps since start.  A
              flap  is  considered  as  a  change of the bfd_status:forwarding
              value.

     Connectivity Fault Management:

       802.1ag Connectivity Fault Management (CFM) allows a group  of  Mainte‐
       nance Points (MPs) called a Maintenance Association (MA) to detect con‐
       nectivity problems with each other. MPs within a MA  should  have  com‐
       plete and exclusive interconnectivity. This is verified by occasionally
       broadcasting Continuity Check Messages (CCMs) at a configurable  trans‐
       mission interval.

       According  to  the 802.1ag specification, each Maintenance Point should
       be configured out-of-band with a list of Remote Maintenance  Points  it
       should  have  connectivity to. Open vSwitch differs from the specifica‐
       tion in this area. It simply assumes the link is faulted if  no  Remote
       Maintenance  Points  are reachable, and considers it not faulted other‐
       wise.

       When operating over tunnels which have no in_key, or an in_key of flow.
       CFM will only accept CCMs with a tunnel key of zero.

       cfm_mpid: optional integer
              A  Maintenance Point ID (MPID) uniquely identifies each endpoint
              within a Maintenance Association. The MPID is used  to  identify
              this endpoint to other Maintenance Points in the MA. Each end of
              a link being monitored should have a  different  MPID.  Must  be
              configured to enable CFM on this Interface.

              According  to  the  802.1ag  specification, MPIDs can only range
              between  [1,  8191].  However,  extended  mode  (see  other_con‐
              fig:cfm_extended) supports eight byte MPIDs.

       cfm_flap_count: optional integer
              Counts the number of cfm fault flapps since boot. A flap is con‐
              sidered to be a change of the cfm_fault value.

       cfm_fault: optional boolean
              Indicates a connectivity fault  triggered  by  an  inability  to
              receive  heartbeats  from  any  remote endpoint. When a fault is
              triggered on Interfaces participating in  bonds,  they  will  be
              disabled.

              Faults  can  be  triggered for several reasons. Most importantly
              they are triggered when no CCMs are received for a period of 3.5
              times  the transmission interval. Faults are also triggered when
              any CCMs indicate that a Remote Maintenance Point is not receiv‐
              ing CCMs but able to send them. Finally, a fault is triggered if
              a CCM is  received  which  indicates  unexpected  configuration.
              Notably,  this  case  arises when a CCM is received which adver‐
              tises the local MPID.

       cfm_fault_status : recv: none
              Indicates a CFM fault was  triggered  due  to  a  lack  of  CCMs
              received on the Interface.

       cfm_fault_status : rdi: none
              Indicates  a  CFM  fault was triggered due to the reception of a
              CCM with the RDI bit flagged. Endpoints set the RDI bit in their
              CCMs when they are not receiving CCMs themselves. This typically
              indicates a unidirectional connectivity failure.

       cfm_fault_status : maid: none
              Indicates a CFM fault was triggered due to the  reception  of  a
              CCM with a MAID other than the one Open vSwitch uses. CFM broad‐
              casts are tagged with an identification number  in  addition  to
              the  MPID  called the MAID. Open vSwitch only supports receiving
              CCM broadcasts tagged with the MAID it uses internally.

       cfm_fault_status : loopback: none
              Indicates a CFM fault was triggered due to the  reception  of  a
              CCM  advertising the same MPID configured in the cfm_mpid column
              of this Interface. This may indicate a loop in the network.

       cfm_fault_status : overflow: none
              Indicates a CFM fault  was  triggered  because  the  CFM  module
              received  CCMs from more remote endpoints than it can keep track
              of.

       cfm_fault_status : override: none
              Indicates a CFM fault was manually triggered by an administrator
              using an ovs-appctl command.

       cfm_fault_status : interval: none
              Indicates  a  CFM  fault was triggered due to the reception of a
              CCM frame having an invalid interval.

       cfm_remote_opstate: optional string, either down or up
              When in extended mode, indicates the operational  state  of  the
              remote   endpoint   as   either   up  or  down.  See  other_con‐
              fig:cfm_opstate.

       cfm_health: optional integer, in range 0 to 100
              Indicates the health of the interface as  a  percentage  of  CCM
              frames  received  over 21 other_config:cfm_intervals. The health
              of an interface is undefined if it is  communicating  with  more
              than  one cfm_remote_mpids. It reduces if healthy heartbeats are
              not received at the expected rate,  and  gradually  improves  as
              healthy  heartbeats  are  received at the desired rate. Every 21
              other_config:cfm_intervals,  the  health  of  the  interface  is
              refreshed.

              As mentioned above, the faults can be triggered for several rea‐
              sons. The link health will deteriorate even  if  heartbeats  are
              received  but  they  are  reported to be unhealthy. An unhealthy
              heartbeat in this context is a heartbeat for which  either  some
              fault  is set or is out of sequence. The interface health can be
              100 only on receiving healthy heartbeats at the desired rate.

       cfm_remote_mpids: set of integers
              When CFM is properly configured, Open vSwitch will  occasionally
              receive CCM broadcasts. These broadcasts contain the MPID of the
              sending Maintenance Point. The list of  MPIDs  from  which  this
              Interface  is  receiving  broadcasts from is regularly collected
              and written to this column.

       other_config : cfm_interval: optional string, containing an integer
              The interval, in  milliseconds,  between  transmissions  of  CFM
              heartbeats. Three missed heartbeat receptions indicate a connec‐
              tivity fault.

              In standard operation only  intervals  of  3,  10,  100,  1,000,
              10,000,  60,000,  or 600,000 ms are supported. Other values will
              be rounded down to the nearest value on the list. Extended  mode
              (see  other_config:cfm_extended)  supports  any  interval  up to
              65,535 ms. In either mode, the default is 1000 ms.

              We do not recommend using intervals less than 100 ms.

       other_config : cfm_extended: optional string, either true or false
              When true, the CFM module operates in extended mode. This causes
              it to use a nonstandard destination address to avoid conflicting
              with compliant implementations which may be running concurrently
              on  the  network. Furthermore, extended mode increases the accu‐
              racy of the cfm_interval  configuration  parameter  by  breaking
              wire  compatibility  with 802.1ag compliant implementations. And
              extended mode allows eight byte MPIDs. Defaults to false.

       other_config : cfm_demand: optional string, either true or false
              When true, and other_config:cfm_extended is true, the CFM module
              operates  in  demand mode. When in demand mode, traffic received
              on the Interface is used to indicate liveness.  CCMs  are  still
              transmitted  and  received.  At  least  one CCM must be received
              every 100 * other_config:cfm_interval amount of time. Otherwise,
              even if traffic are received, the CFM module will raise the con‐
              nectivity fault.

              Demand mode has a couple of caveats:

              ·      To ensure that ovs-vswitchd has enough time to pull  sta‐
                     tistics  from  the datapath, the fault detection interval
                     is set to 3.5 * MAX(other_config:cfm_interval, 500) ms.

              ·      To avoid ambiguity,  demand  mode  disables  itself  when
                     there are multiple remote maintenance points.

              ·      If  the  Interface  is heavily congested, CCMs containing
                     the other_config:cfm_opstate status may be dropped  caus‐
                     ing changes in the operational state to be delayed. Simi‐
                     larly, if CCMs containing the RDI bit are  not  received,
                     unidirectional link failures may not be detected.

       other_config : cfm_opstate: optional string, either down or up
              When  down, the CFM module marks all CCMs it generates as opera‐
              tionally down without triggering a  fault.  This  allows  remote
              maintenance  points  to  choose  not  to  forward traffic to the
              Interface on which this CFM module  is  running.  Currently,  in
              Open vSwitch, the opdown bit of CCMs affects Interfaces partici‐
              pating in bonds, and the bundle OpenFlow action. This setting is
              ignored when CFM is not in extended mode. Defaults to up.

       other_config : cfm_ccm_vlan: optional string, containing an integer, in
       range 1 to 4,095
              When set, the CFM module will apply a VLAN tag to  all  CCMs  it
              generates  with  the  given  value.  May be the string random in
              which case each CCM will be tagged  with  a  different  randomly
              generated VLAN.

       other_config  : cfm_ccm_pcp: optional string, containing an integer, in
       range 1 to 7
              When set, the CFM module will apply a VLAN tag to  all  CCMs  it
              generates  with  the  given PCP value, the VLAN ID of the tag is
              governed  by  the   value   of   other_config:cfm_ccm_vlan.   If
              other_config:cfm_ccm_vlan is unset, a VLAN ID of zero is used.

     Bonding Configuration:

       other_config : lacp-port-id: optional string, containing an integer, in
       range 1 to 65,535
              The LACP port ID of this Interface. Port IDs are  used  in  LACP
              negotiations  to  identify  individual  ports participating in a
              bond.

       other_config : lacp-port-priority: optional string, containing an inte‐
       ger, in range 1 to 65,535
              The  LACP  port priority of this Interface. In LACP negotiations
              Interfaces with numerically lower priorities are  preferred  for
              aggregation.

       other_config  :  lacp-aggregation-key:  optional  string, containing an
       integer, in range 1 to 65,535
              The LACP aggregation key of this Interface. Interfaces with dif‐
              ferent aggregation keys may not be active within a given Port at
              the same time.

     Virtual Machine Identifiers:

       These key-value pairs specifically apply to an  interface  that  repre‐
       sents  a  virtual  Ethernet  interface  connected to a virtual machine.
       These key-value pairs should not be present for other types  of  inter‐
       faces. Keys whose names end in -uuid have values that uniquely identify
       the entity in question. For a Citrix XenServer hypervisor, these values
       are UUIDs in RFC 4122 format. Other hypervisors may use other formats.

       external_ids : attached-mac: optional string
              The  MAC  address  programmed  into the ``virtual hardware’’ for
              this  interface,  in  the  form  xx:xx:xx:xx:xx:xx.  For  Citrix
              XenServer,  this is the value of the MAC field in the VIF record
              for this interface.

       external_ids : iface-id: optional string
              A system-unique identifier for the interface. On XenServer, this
              will commonly be the same as external_ids:xs-vif-uuid.

       external_ids : iface-status: optional string, either active or inactive
              Hypervisors  may  sometimes have more than one interface associ‐
              ated with a given external_ids:iface-id, only one  of  which  is
              actually  in  use  at a given time. For example, in some circum‐
              stances XenServer has both a ``tap’’ and a ``vif’’ interface for
              a  single  external_ids:iface-id, but only uses one of them at a
              time. A hypervisor that behaves this way must mark the currently
              in  use  interface  active and the others inactive. A hypervisor
              that never has more  than  one  interface  for  a  given  exter‐
              nal_ids:iface-id  may  mark that interface active or omit exter‐
              nal_ids:iface-status entirely.

              During VM migration, a given external_ids:iface-id  might  tran‐
              siently  be marked active on two different hypervisors. That is,
              active means  that  this  external_ids:iface-id  is  the  active
              instance  within  a  single  hypervisor, not in a broader scope.
              There is one exception: some hypervisors  support  ``migration’’
              from  a  given  hypervisor  to  itself (most often for test pur‐
              poses). During such a ``migration,’’ two instances of  a  single
              external_ids:iface-id  might  both be briefly marked active on a
              single hypervisor.

       external_ids : xs-vif-uuid: optional string
              The virtual interface associated with this interface.

       external_ids : xs-network-uuid: optional string
              The virtual network to which this interface is attached.

       external_ids : vm-id: optional string
              The VM to which this interface belongs. On XenServer, this  will
              be the same as external_ids:xs-vm-uuid.

       external_ids : xs-vm-uuid: optional string
              The VM to which this interface belongs.

     Auto Attach Configuration:

       Auto Attach configuration for a particular interface.

       lldp : enable: optional string, either true or false
              True  to  enable  LLDP on this Interface. If not specified, LLDP
              will be disabled by default.

     Flow control Configuration:

       Ethernet flow control defined in IEEE 802.1Qbb provides link level flow
       control  using  MAC  pause frames. Implemented only for interfaces with
       type dpdk.

       options : rx-flow-ctrl: optional string, either true or false
              Set to true to enable Rx flow  control  on  physical  ports.  By
              default, Rx flow control is disabled.

       options : tx-flow-ctrl: optional string, either true or false
              Set  to  true  to  enable  Tx flow control on physical ports. By
              default, Tx flow control is disabled.

       options : flow-ctrl-autoneg: optional string, either true or false
              Set to true to enable flow control auto negotiation on  physical
              ports. By default, auto-neg is disabled.

     Link State Change detection mode:

       options : dpdk-lsc-interrupt: optional string, either true or false
              Set  this  value  to  true  to configure interrupt mode for Link
              State Change (LSC) detection instead of poll mode for  the  DPDK
              interface.

              If this value is not set, poll mode is configured.

              This parameter has an effect only on netdev dpdk interfaces.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Flow_Table TABLE
       Configuration for a particular OpenFlow table.

   Summary:
       name                          optional string
       Eviction Policy:
         flow_limit                  optional integer, at least 0
         overflow_policy             optional string, either evict or refuse
         groups                      set of strings
       Classifier Optimization:
         prefixes                    set of up to 3 strings
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       name: optional string
              The table’s name. Set this column to change the name  that  con‐
              trollers  will  receive when they request table statistics, e.g.
              ovs-ofctl dump-tables. The name does not affect switch behavior.

     Eviction Policy:

       Open vSwitch  supports  limiting  the  number  of  flows  that  may  be
       installed  in  a  flow  table, via the flow_limit column. When adding a
       flow would exceed this limit, by default Open vSwitch reports an error,
       but  there  are  two  ways  to configure Open vSwitch to instead delete
       (``evict’’) a flow to make room for the new one:

              ·      Set the overflow_policy column to evict.

              ·      Send an OpenFlow 1.4+ ``table  mod  request’’  to  enable
                     eviction for the flow table (e.g. ovs-ofctl -O OpenFlow14
                     mod-table br0 0 evict to enable eviction on flow table  0
                     of bridge br0).

       When  a flow must be evicted due to overflow, the flow to evict is cho‐
       sen through an approximation of the following algorithm. This algorithm
       is used regardless of how eviction was enabled:

              1.  Divide  the flows in the table into groups based on the val‐
                  ues of the fields or subfields specified in the groups  col‐
                  umn, so that all of the flows in a given group have the same
                  values for those fields. If a flow does not specify a  given
                  field,  that  field’s  value  is  treated as 0. If groups is
                  empty, then all of the flows in the flow table  are  treated
                  as a single group.

              2.  Consider  the flows in the largest group, that is, the group
                  that contains the greatest number of flows. If two  or  more
                  groups  all  have the same largest number of flows, consider
                  the flows in all of those groups.

              3.  If the flows under consideration have  different  importance
                  values,  eliminate from consideration any flows except those
                  with the lowest importance. (``Importance,’’ a 16-bit  inte‐
                  ger  value attached to each flow, was introduced in OpenFlow
                  1.4. Flows inserted with older versions of  OpenFlow  always
                  have an importance of 0.)

              4.  Among  the  flows  under consideration, choose the flow that
                  expires soonest for eviction.

       The eviction process only considers flows that have an idle timeout  or
       a  hard timeout. That is, eviction never deletes permanent flows. (Per‐
       manent flows do count against flow_limit.)

       flow_limit: optional integer, at least 0
              If set, limits the number of flows that may be added to the  ta‐
              ble.  Open  vSwitch may limit the number of flows in a table for
              other reasons, e.g. due to hardware limitations or for  resource
              availability or performance reasons.

       overflow_policy: optional string, either evict or refuse
              Controls the switch’s behavior when an OpenFlow flow table modi‐
              fication request would add flows in excess  of  flow_limit.  The
              supported values are:

              refuse Refuse to add the flow or flows. This is also the default
                     policy when overflow_policy is unset.

              evict  Delete a flow chosen according to the algorithm described
                     above.

       groups: set of strings
              When  overflow_policy is evict, this controls how flows are cho‐
              sen for eviction when the  flow  table  would  otherwise  exceed
              flow_limit  flows.  Its  value  is  a  set of NXM fields or sub-
              fields, each  of  which  takes  one  of  the  forms  field[]  or
              field[start..end], e.g. NXM_OF_IN_PORT[]. Please see meta-flow.h
              for a complete list of NXM field names.

              Open vSwitch ignores any invalid  or  unknown  field  specifica‐
              tions.

              When eviction is not enabled, via overflow_policy or an OpenFlow
              1.4+ ``table mod,’’ this column has no effect.

     Classifier Optimization:

       prefixes: set of up to 3 strings
              This string set  specifies  which  fields  should  be  used  for
              address  prefix  tracking. Prefix tracking allows the classifier
              to skip rules with longer than necessary prefixes, resulting  in
              better wildcarding for datapath flows.

              Prefix  tracking  may  be  beneficial when a flow table contains
              matches on IP address fields with different prefix lengths.  For
              example,  when  a flow table contains IP address matches on both
              full addresses and proper prefixes,  the  full  address  matches
              will  typically cause the datapath flow to un-wildcard the whole
              address field (depending on flow entry priorities). In this case
              each  packet  with  a  different  address  gets  handed  to  the
              userspace for flow processing and  generates  its  own  datapath
              flow.  With  prefix  tracking  enabled  for the address field in
              question packets with addresses matching shorter prefixes  would
              generate  datapath  flows  where the irrelevant address bits are
              wildcarded, allowing the same datapath flow to  handle  all  the
              packets  within  the  prefix  in  question.  In  this  case many
              userspace upcalls can be avoided and the overall performance can
              be better.

              This is a performance optimization only, so packets will receive
              the same treatment with or without prefix tracking.

              The   supported   fields   are:   tun_id,   tun_src,    tun_dst,
              tun_ipv6_src,  tun_ipv6_dst,  nw_src,  nw_dst (or aliases ip_src
              and ip_dst), ipv6_src, and ipv6_dst.  (Using  this  feature  for
              tun_id  would  only  make  sense  if  the tunnel IDs have prefix
              structure similar to IP addresses.)

              By default, the prefixes=ip_dst,ip_src are used on each flow ta‐
              ble. This instructs the flow classifier to track the IP destina‐
              tion and source addresses used by the  rules  in  this  specific
              flow table.

              The  keyword  none  is recognized as an explicit override of the
              default values, causing no prefix fields to be tracked.

              To set the prefix fields, the flow table record needs to exist:

              ovs-vsctl set Bridge br0 flow_tables:0=@N1  --  --id=@N1  create
              Flow_Table name=table0
                     Creates a flow table record for the OpenFlow table number
                     0.

              ovs-vsctl set Flow_Table table0 prefixes=ip_dst,ip_src
                     Enables prefix tracking for  IP  source  and  destination
                     address fields.

              There  is a maximum number of fields that can be enabled for any
              one flow table. Currently this limit is 3.

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

QoS TABLE
       Quality  of  Service  (QoS) configuration for each Port that references
       it.

   Summary:
       type                          string
       queues                        map of integer-Queue pairs, key in  range
                                     0 to 4,294,967,295
       Configuration for linux-htb and linux-hfsc:
         other_config : max-rate     optional string, containing an integer
       Configuration for egress-policer QoS:
         other_config : cir          optional string, containing an integer
         other_config : cbs          optional string, containing an integer
         other_config : eir          optional string, containing an integer
         other_config : ebs          optional string, containing an integer
       Configuration for linux-sfq:
         other_config : perturb      optional string, containing an integer
         other_config : quantum      optional string, containing an integer
       Configuration for linux-netem:
         other_config : latency      optional string, containing an integer
         other_config : limit        optional string, containing an integer
         other_config : loss         optional string, containing an integer
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
       type: string
              The  type  of  QoS to implement. The currently defined types are
              listed below:

              linux-htb
                     Linux ``hierarchy  token  bucket’’  classifier.  See  tc-
                     htb(8)  (also  at  http://linux.die.net/man/8/tc-htb) and
                     the HTB  manual  (http://luxik.cdi.cz/~devik/qos/htb/man‐
                     ual/userg.htm)  for  information  on  how this classifier
                     works and how to configure it.

              linux-hfsc
                     Linux "Hierarchical Fair Service Curve"  classifier.  See
                     http://linux-ip.net/articles/hfsc.en/  for information on
                     how this classifier works.

              linux-sfq
                     Linux ``Stochastic Fairness  Queueing’’  classifier.  See
                     tc-sfq(8) (also at http://linux.die.net/man/8/tc-sfq) for
                     information on how this classifier works.

              linux-codel
                     Linux ``Controlled Delay’’  classifier.  See  tc-codel(8)
                     (also                                                  at
                     http://man7.org/linux/man-pages/man8/tc-codel.8.html) for
                     information on how this classifier works.

              linux-fq_codel
                     Linux  ``Fair Queuing with Controlled Delay’’ classifier.
                     See           tc-fq_codel(8)           (also           at
                     http://man7.org/linux/man-pages/man8/tc-fq_codel.8.html)
                     for information on how this classifier works.

              linux-netem
                     Linux ``Network Emulator’’  classifier.  See  tc-netem(8)
                     (also                                                  at
                     http://man7.org/linux/man-pages/man8/tc-netem.8.html) for
                     information on how this classifier works.

              linux-noop
                     Linux  ``No operation.’’ By default, Open vSwitch manages
                     quality of service on all of its configured  ports.  This
                     can  be  helpful,  but sometimes administrators prefer to
                     use other software to manage QoS. This type prevents Open
                     vSwitch from changing the QoS configuration for a port.

              egress-policer
                     A  DPDK egress policer algorithm using the DPDK rte_meter
                     library. The rte_meter library provides an implementation
                     which  allows  the  metering and policing of traffic. The
                     implementation in OVS essentially creates a single  token
                     bucket  used  to  police traffic. It should be noted that
                     when the rte_meter is configured as  part  of  QoS  there
                     will  be  a  performance overhead as the rte_meter itself
                     will consume CPU cycles in order to police traffic. These
                     CPU cycles ordinarily are used for packet proccessing. As
                     such the drop in performance will be noticed in terms  of
                     overall aggregate traffic throughput.

              trtcm-policer
                     A  DPDK  egress  policer  algorithm using RFC 4115’s Two-
                     Rate, Three-Color marker. It’s a  two-level  hierarchical
                     policer  which  first  does  a color-blind marking of the
                     traffic at the queue level,  followed  by  a  color-aware
                     marking  at  the port level. At the end traffic marked as
                     Green or Yellow is forwarded, Red is dropped. For details
                     on  how traffic is marked, see RFC 4115. If the ``default
                     queue’’, 0, is not configured it’s automatically  created
                     with the same other_config values as the physical port.

       queues: map of integer-Queue pairs, key in range 0 to 4,294,967,295
              A  map  from queue numbers to Queue records. The supported range
              of queue numbers depend on type. The queue numbers are the  same
              as  the  queue_id  used in OpenFlow in struct ofp_action_enqueue
              and other structures.

              Queue 0 is the ``default queue.’’ It is used by OpenFlow  output
              actions  when no specific queue has been set. When no configura‐
              tion for queue 0 is present, it is automatically  configured  as
              if  a  Queue record with empty dscp and other_config columns had
              been specified. (Before version 1.6, Open  vSwitch  would  leave
              queue  0  unconfigured  in  this  case. With some queuing disci‐
              plines, this  dropped  all  packets  destined  for  the  default
              queue.)

     Configuration for linux-htb and linux-hfsc:

       The  linux-htb  and  linux-hfsc classes support the following key-value
       pair:

       other_config : max-rate: optional string, containing an integer
              Maximum rate shared by all queued traffic, in  bit/s.  Optional.
              If  not  specified,  for physical interfaces, the default is the
              link rate. For other interfaces or if the link  rate  cannot  be
              determined, the default is currently 100 Mbps.

     Configuration for egress-policer QoS:

       QoS  type  egress-policer  provides  egress policing for userspace port
       types with DPDK. It has the following key-value pairs defined.

       other_config : cir: optional string, containing an integer
              The Committed Information Rate (CIR) is measured in bytes of  IP
              packets per second, i.e. it includes the IP header, but not link
              specific (e.g. Ethernet) headers. This represents the bytes  per
              second  rate  at which the token bucket will be updated. The cir
              value is calculated by (pps x packet  data  size).  For  example
              assuming  a  user wishes to limit a stream consisting of 64 byte
              packets to 1 million packets per second the CIR would be set  to
              to  to 46000000. This value can be broken into ’1,000,000 x 46’.
              Where 1,000,000 is the policing rate for the number  of  packets
              per  second  and 46 represents the size of the packet data for a
              64 byte ip packet.

       other_config : cbs: optional string, containing an integer
              The Committed Burst Size (CBS) is measured in bytes  and  repre‐
              sents  a  token bucket. At a minimum this value should be be set
              to the expected largest size packet in the  traffic  stream.  In
              practice  larger  values may be used to increase the size of the
              token bucket. If a packet can be transmitted then the  cbs  will
              be  decremented  by the number of bytes/tokens of the packet. If
              there are not enough tokens in the cbs bucket the packet will be
              dropped.

       other_config : eir: optional string, containing an integer
              The  Excess  Information  Rate  (EIR) is measured in bytes of IP
              packets per second, i.e. it includes the IP header, but not link
              specific  (e.g. Ethernet) headers. This represents the bytes per
              second rate at which the token bucket will be updated.  The  eir
              value  is  calculated  by  (pps x packet data size). For example
              assuming a user wishes to limit a stream consisting of  64  byte
              packets  to 1 million packets per second the EIR would be set to
              to to 46000000. This value can be broken into ’1,000,000 x  46’.
              Where  1,000,000  is the policing rate for the number of packets
              per second and 46 represents the size of the packet data  for  a
              64 byte ip packet.

       other_config : ebs: optional string, containing an integer
              The  Excess Burst Size (EBS) is measured in bytes and represents
              a token bucket. At a minimum this value should be be set to  the
              expected  largest size packet in the traffic stream. In practice
              larger values may be used to increase  the  size  of  the  token
              bucket.  If  a  packet  can  be transmitted then the ebs will be
              decremented by the number of  bytes/tokens  of  the  packet.  If
              there  are  not enough tokens in the cbs bucket the packet might
              be dropped.

     Configuration for linux-sfq:

       The linux-sfq QoS supports the following key-value pairs:

       other_config : perturb: optional string, containing an integer
              Number of seconds between consecutive perturbations  in  hashing
              algorithm.  Different  flows  can end up in the same hash bucket
              causing unfairness. Perturbation’s goal is  to  remove  possible
              unfairness.  The  default and recommended value is 10. Too low a
              value is discouraged because each perturbation can cause  packet
              reordering.

       other_config : quantum: optional string, containing an integer
              Number  of bytes linux-sfq QoS can dequeue in one turn in round-
              robin from one flow. The default and recommended value is  equal
              to interface’s MTU.

     Configuration for linux-netem:

       The linux-netem QoS supports the following key-value pairs:

       other_config : latency: optional string, containing an integer
              Adds  the chosen delay to the packets outgoing to chosen network
              interface. The latency value expressed in us.

       other_config : limit: optional string, containing an integer
              Maximum number of packets the qdisc may hold queued at  a  time.
              The default value is 1000.

       other_config : loss: optional string, containing an integer
              Adds  an  independent  loss  probability to the packets outgoing
              from the chosen network interface.

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Queue TABLE
       A configuration for a port output queue, used in configuring Quality of
       Service (QoS) features. May be referenced by queues column in  QoS  ta‐
       ble.

   Summary:
       dscp                          optional integer, in range 0 to 63
       Configuration for linux-htb QoS:
         other_config : min-rate     optional  string,  containing an integer,
                                     at least 1
         other_config : max-rate     optional string, containing  an  integer,
                                     at least 1
         other_config : burst        optional  string,  containing an integer,
                                     at least 1
         other_config : priority     optional string, containing  an  integer,
                                     in range 0 to 4,294,967,295
       Configuration for linux-hfsc QoS:
         other_config : min-rate     optional  string,  containing an integer,
                                     at least 1
         other_config : max-rate     optional string, containing  an  integer,
                                     at least 1
       Common Columns:
         other_config                map of string-string pairs
         external_ids                map of string-string pairs

   Details:
       dscp: optional integer, in range 0 to 63
              If  set, Open vSwitch will mark all traffic egressing this Queue
              with the given DSCP bits. Traffic egressing the default Queue is
              only  marked  if  it was explicitly selected as the Queue at the
              time the packet was output. If unset, the DSCP bits  of  traffic
              egressing this Queue will remain unchanged.

     Configuration for linux-htb QoS:

       QoS  type  linux-htb may use queue_ids less than 61440. It has the fol‐
       lowing key-value pairs defined.

       other_config : min-rate: optional string,  containing  an  integer,  at
       least 1
              Minimum guaranteed bandwidth, in bit/s.

       other_config  :  max-rate:  optional  string, containing an integer, at
       least 1
              Maximum allowed bandwidth, in bit/s. Optional. If specified, the
              queue’s  rate will not be allowed to exceed the specified value,
              even if excess bandwidth is available. If unspecified,  defaults
              to no limit.

       other_config  : burst: optional string, containing an integer, at least
       1
              Burst size, in bits. This is the maximum amount  of  ``credits’’
              that  a queue can accumulate while it is idle. Optional. Details
              of the linux-htb implementation require a minimum burst size, so
              a too-small burst will be silently ignored.

       other_config  :  priority:  optional  string, containing an integer, in
       range 0 to 4,294,967,295
              A queue with a smaller priority  will  receive  all  the  excess
              bandwidth  that  it  can  use before a queue with a larger value
              receives any. Specific priority  values  are  unimportant;  only
              relative ordering matters. Defaults to 0 if unspecified.

     Configuration for linux-hfsc QoS:

       QoS  type linux-hfsc may use queue_ids less than 61440. It has the fol‐
       lowing key-value pairs defined.

       other_config : min-rate: optional string,  containing  an  integer,  at
       least 1
              Minimum guaranteed bandwidth, in bit/s.

       other_config  :  max-rate:  optional  string, containing an integer, at
       least 1
              Maximum allowed bandwidth, in bit/s. Optional. If specified, the
              queue’s  rate will not be allowed to exceed the specified value,
              even if excess bandwidth is available. If unspecified,  defaults
              to no limit.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       other_config: map of string-string pairs

       external_ids: map of string-string pairs

Mirror TABLE
       A port mirror within a Bridge.

       A port mirror configures a bridge to send selected  frames  to  special
       ``mirrored’’ ports, in addition to their normal destinations. Mirroring
       traffic may also be referred to as SPAN or RSPAN, depending on how  the
       mirrored traffic is sent.

       When  a  packet  enters an Open vSwitch bridge, it becomes eligible for
       mirroring based on its ingress port and VLAN.  As  the  packet  travels
       through  the  flow tables, each time it is output to a port, it becomes
       eligible for mirroring based on the  egress  port  and  VLAN.  In  Open
       vSwitch  2.5  and  later,  mirroring  occurs  just after a packet first
       becomes eligible, using the packet as it exists at that point; in  Open
       vSwitch  2.4 and earlier, mirroring occurs only after a packet has tra‐
       versed all the flow tables, using the original packet as it entered the
       bridge.  This  makes a difference only when the flow table modifies the
       packet: in Open vSwitch 2.4, the modifications  are  never  visible  to
       mirrors,  whereas  in  Open  vSwitch  2.5  and later modifications made
       before the first output that makes it eligible for mirroring to a  par‐
       ticular destination are visible.

       A packet that enters an Open vSwitch bridge is mirrored to a particular
       destination only once, even if it is eligible for multiple reasons. For
       example,  a  packet  would be mirrored to a particular output_port only
       once,  even  if  it  is  selected  for  mirroring  to  that   port   by
       select_dst_port  and  select_src_port  in  the same or different Mirror
       records.

   Summary:
       name                          string
       Selecting Packets for Mirroring:
         select_all                  boolean
         select_dst_port             set of weak reference to Ports
         select_src_port             set of weak reference to Ports
         select_vlan                 set of up to 4,096 integers, in  range  0
                                     to 4,095
       Mirroring Destination Configuration:
         output_port                 optional weak reference to Port
         output_vlan                 optional integer, in range 1 to 4,095
         snaplen                     optional integer, in range 14 to 65,535
       Statistics: Mirror counters:
         statistics : tx_packets     optional integer
         statistics : tx_bytes       optional integer
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       name: string
              Arbitrary identifier for the Mirror.

     Selecting Packets for Mirroring:

       To  be  selected  for mirroring, a given packet must enter or leave the
       bridge through a selected port and it  must  also  be  in  one  of  the
       selected VLANs.

       select_all: boolean
              If  true,  every  packet  arriving  or  departing on any port is
              selected for mirroring.

       select_dst_port: set of weak reference to Ports
              Ports on which departing packets are selected for mirroring.

       select_src_port: set of weak reference to Ports
              Ports on which arriving packets are selected for mirroring.

       select_vlan: set of up to 4,096 integers, in range 0 to 4,095
              VLANs on which packets are selected for mirroring. An empty  set
              selects packets on all VLANs.

     Mirroring Destination Configuration:

       These  columns  are  mutually  exclusive.  Exactly  one of them must be
       nonempty.

       output_port: optional weak reference to Port
              Output port for selected packets, if nonempty.

              Specifying a port for mirror output reserves  that  port  exclu‐
              sively  for  mirroring.  No frames other than those selected for
              mirroring via this column will be forwarded to the port, and any
              frames received on the port will be discarded.

              The  output  port  may  be  any  kind  of port supported by Open
              vSwitch. It may be, for  example,  a  physical  port  (sometimes
              called SPAN) or a GRE tunnel.

       output_vlan: optional integer, in range 1 to 4,095
              Output VLAN for selected packets, if nonempty.

              The frames will be sent out all ports that trunk output_vlan, as
              well as any ports with implicit VLAN output_vlan.  When  a  mir‐
              rored  frame is sent out a trunk port, the frame’s VLAN tag will
              be set to output_vlan, replacing any existing tag;  when  it  is
              sent  out  an  implicit VLAN port, the frame will not be tagged.
              This type of mirroring is sometimes called RSPAN.

              See  the  documentation  for  other_config:forward-bpdu  in  the
              Interface  table  for  a list of destination MAC addresses which
              will not be mirrored to a VLAN to avoid confusing switches  that
              interpret the protocols that they represent.

              Please note: Mirroring to a VLAN can disrupt a network that con‐
              tains unmanaged switches. Consider an unmanaged physical  switch
              with  two  ports:  port 1, connected to an end host, and port 2,
              connected to an Open vSwitch configured to mirror received pack‐
              ets  into  VLAN 123 on port 2. Suppose that the end host sends a
              packet on port 1 that the physical switch forwards  to  port  2.
              The  Open  vSwitch  forwards  this packet to its destination and
              then reflects it back on port 2  in  VLAN  123.  This  reflected
              packet  causes  the unmanaged physical switch to replace the MAC
              learning table entry, which correctly pointed to  port  1,  with
              one  that  incorrectly points to port 2. Afterward, the physical
              switch will direct packets destined for the end host to the Open
              vSwitch  on  port  2, instead of to the end host on port 1, dis‐
              rupting connectivity. If mirroring to a VLAN is desired in  this
              scenario,  then the physical switch must be replaced by one that
              learns Ethernet addresses on  a  per-VLAN  basis.  In  addition,
              learning  should  be  disabled  on  the VLAN containing mirrored
              traffic. If this is not done  then  intermediate  switches  will
              learn  the  MAC address of each end host from the mirrored traf‐
              fic. If packets being sent to that end host are  also  mirrored,
              then  they will be dropped since the switch will attempt to send
              them out the input port. Disabling learning for  the  VLAN  will
              cause the switch to correctly send the packet out all ports con‐
              figured for that VLAN. If Open  vSwitch  is  being  used  as  an
              intermediate switch, learning can be disabled by adding the mir‐
              rored VLAN to flood_vlans in the  appropriate  Bridge  table  or
              tables.

              Mirroring  to a GRE tunnel has fewer caveats than mirroring to a
              VLAN and should generally be preferred.

       snaplen: optional integer, in range 14 to 65,535
              Maximum per-packet number of bytes to mirror.

              A mirrored packet with size larger than snaplen  will  be  trun‐
              cated  in datapath to snaplen bytes before sending to the mirror
              output port. If omitted, packets are not truncated.

     Statistics: Mirror counters:

       Key-value pairs that report mirror statistics.  The  update  period  is
       controlled  by  other_config:stats-update-interval  in the Open_vSwitch
       table.

       statistics : tx_packets: optional integer
              Number of packets transmitted through this mirror.

       statistics : tx_bytes: optional integer
              Number of bytes transmitted through this mirror.

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

Controller TABLE
       An OpenFlow controller.

   Summary:
       Core Features:
         type                        optional  string,  either primary or ser‐
                                     vice
         target                      string
         connection_mode             optional  string,   either   in-band   or
                                     out-of-band
       Controller Failure Detection and Handling:
         max_backoff                 optional integer, at least 1,000
         inactivity_probe            optional integer
       Asynchronous Messages:
         enable_async_messages       optional boolean
         Controller Rate Limiting:
            controller_queue_size    optional integer, in range 1 to 512
            controller_rate_limit    optional integer, at least 100
            controller_burst_limit   optional integer, at least 25
            Controller Rate Limiting Statistics:
              status : packet-in-TYPE-bypassed
                                     optional  string,  containing an integer,
                                     at least 0
              status : packet-in-TYPE-queued
                                     optional string, containing  an  integer,
                                     at least 0
              status : packet-in-TYPE-dropped
                                     optional  string,  containing an integer,
                                     at least 0
              status : packet-in-TYPE-backlog
                                     optional string, containing  an  integer,
                                     at least 0
       Additional In-Band Configuration:
         local_ip                    optional string
         local_netmask               optional string
         local_gateway               optional string
       Controller Status:
         is_connected                boolean
         role                        optional string, one of master, other, or
                                     slave
         status : last_error         optional string
         status : state              optional string, one of ACTIVE,  BACKOFF,
                                     CONNECTING, IDLE, or VOID
         status : sec_since_connect  optional  string,  containing an integer,
                                     at least 0
         status : sec_since_disconnect
                                     optional string, containing  an  integer,
                                     at least 1
       Connection Parameters:
         other_config : dscp         optional string, containing an integer
       Common Columns:
         external_ids                map of string-string pairs
         other_config                map of string-string pairs

   Details:
     Core Features:

       type: optional string, either primary or service
              Open  vSwitch  supports  two  kinds  of  OpenFlow controllers. A
              bridge may have any number of each kind:

              Primary controllers
                     This is the kind of controller envisioned by the OpenFlow
                     specifications.  Usually, a primary controller implements
                     a network policy by taking charge of  the  switch’s  flow
                     table.

                     The  fail_mode column in the Bridge table applies to pri‐
                     mary controllers.

                     When multiple primary controllers  are  configured,  Open
                     vSwitch  connects to all of them simultaneously. OpenFlow
                     provides few facilities to allow multiple controllers  to
                     coordinate  in  interacting with a single switch, so more
                     than one primary controller should be specified  only  if
                     the  controllers  are  themselves  designed to coordinate
                     with each other.

              Service controllers
                     These  kinds  of  OpenFlow  controller  connections   are
                     intended for occasional support and maintenance use, e.g.
                     with ovs-ofctl. Usually  a  service  controller  connects
                     only  briefly  to  inspect  or  modify some of a switch’s
                     state.

                     The fail_mode column in the Bridge table does  not  apply
                     to service controllers.

              By  default, Open vSwitch treats controllers with active connec‐
              tion methods as primary controllers and those with passive  con‐
              nection  methods  as service controllers. Set this column to the
              desired type to override this default.

       target: string
              Connection method for controller.

              The following active connection methods are currently supported:

              ssl:host[:port]
                     The specified SSL port on the host  at  the  given  host,
                     which  can  either  be  a DNS name (if built with unbound
                     library)  or  an  IP  address.  The  ssl  column  in  the
                     Open_vSwitch  table  must point to a valid SSL configura‐
                     tion when this form is used.

                     If port is not specified, it defaults to 6653.

                     SSL support is an optional feature  that  is  not  always
                     built as part of Open vSwitch.

              tcp:host[:port]
                     The  specified  TCP  port  on the host at the given host,
                     which can either be a DNS name  (if  built  with  unbound
                     library)  or  an IP address (IPv4 or IPv6). If host is an
                     IPv6  address,  wrap  it   in   square   brackets,   e.g.
                     tcp:[::1]:6653.

                     If port is not specified, it defaults to 6653.

              The  following  passive  connection  methods  are currently sup‐
              ported:

              pssl:[port][:host]
                     Listens for SSL connections on the specified TCP port. If
                     host,  which  can  either  be  a  DNS name (if built with
                     unbound library) or an IP  address,  is  specified,  then
                     connections  are  restricted to the resolved or specified
                     local IP address (either IPv4 or IPv6).  If  host  is  an
                     IPv6   address,   wrap   it   in  square  brackets,  e.g.
                     pssl:6653:[::1].

                     If port is not specified, it defaults to 6653. If host is
                     not specified then it listens only on IPv4 (but not IPv6)
                     addresses. The ssl column in the Open_vSwitch table  must
                     point  to  a  valid  SSL  configuration when this form is
                     used.

                     If port is not specified, it currently to 6653.

                     SSL support is an optional feature  that  is  not  always
                     built as part of Open vSwitch.

              ptcp:[port][:host]
                     Listens  for  connections  on  the specified TCP port. If
                     host, which can either be  a  DNS  name  (if  built  with
                     unbound  library)  or  an  IP address, is specified, then
                     connections are restricted to the resolved  or  specified
                     local  IP  address  (either  IPv4 or IPv6). If host is an
                     IPv6  address,  wrap  it   in   square   brackets,   e.g.
                     ptcp:6653:[::1]. If host is not specified then it listens
                     only on IPv4 addresses.

                     If port is not specified, it defaults to 6653.

              When multiple controllers are configured for  a  single  bridge,
              the  target values must be unique. Duplicate target values yield
              unspecified results.

       connection_mode: optional string, either in-band or out-of-band
              If it is specified, this setting must be one  of  the  following
              strings  that  describes how Open vSwitch contacts this OpenFlow
              controller over the network:

              in-band
                     In this mode, this controller’s OpenFlow traffic  travels
                     over the bridge associated with the controller. With this
                     setting, Open vSwitch allows traffic to and from the con‐
                     troller  regardless  of the contents of the OpenFlow flow
                     table. (Otherwise, Open vSwitch would never  be  able  to
                     connect to the controller, because it did not have a flow
                     to enable it.) This is the most  common  connection  mode
                     because  it  is not necessary to maintain two independent
                     networks.

              out-of-band
                     In this mode, OpenFlow traffic  uses  a  control  network
                     separate from the bridge associated with this controller,
                     that is, the bridge does not use any of its  own  network
                     devices  to  communicate with the controller. The control
                     network must be configured separately,  before  or  after
                     ovs-vswitchd is started.

              If not specified, the default is implementation-specific.

     Controller Failure Detection and Handling:

       max_backoff: optional integer, at least 1,000
              Maximum  number  of  milliseconds  to  wait  between  connection
              attempts. Default is implementation-specific.

       inactivity_probe: optional integer
              Maximum number of milliseconds of idle  time  on  connection  to
              controller  before  sending an inactivity probe message. If Open
              vSwitch does not communicate with the controller for the  speci‐
              fied  number  of seconds, it will send a probe. If a response is
              not received for  the  same  additional  amount  of  time,  Open
              vSwitch  assumes  the connection has been broken and attempts to
              reconnect. Default is implementation-specific. A value of 0 dis‐
              ables inactivity probes.

     Asynchronous Messages:

       OpenFlow  switches send certain messages to controllers spontanenously,
       that is, not in response to any request from the controller. These mes‐
       sages  are  called ``asynchronous messages.’’ These columns allow asyn‐
       chronous messages to be limited or disabled to ensure the best  use  of
       network resources.

       enable_async_messages: optional boolean
              The  OpenFlow  protocol enables asynchronous messages at time of
              connection establishment, which  means  that  a  controller  can
              receive asynchronous messages, potentially many of them, even if
              it turns them off immediately after connecting. Set this  column
              to false to change Open vSwitch behavior to disable, by default,
              all  asynchronous  messages.  The   controller   can   use   the
              NXT_SET_ASYNC_CONFIG Nicira extension to OpenFlow to turn on any
              messages that it does want to receive, if any.

     Controller Rate Limiting:

       A switch can forward packets to a controller over the  OpenFlow  proto‐
       col.  Forwarding  packets  this  way at too high a rate can overwhelm a
       controller, frustrate use of the OpenFlow  connection  for  other  pur‐
       poses,  increase  the  latency  of  flow setup, and use an unreasonable
       amount of bandwidth. Therefore, Open vSwitch supports limiting the rate
       of packet forwarding to a controller.

       There  are  two  main  reasons in OpenFlow for a packet to be sent to a
       controller: either the packet ``misses’’ in the flow  table,  that  is,
       there  is  no  matching  flow,  or a flow table action says to send the
       packet to the controller. Open vSwitch limits the rate of each kind  of
       packet  separately  at  the configured rate. Therefore, the actual rate
       that packets are sent to the controller can be up to twice the  config‐
       ured rate, when packets are sent for both reasons.

       This feature is specific to forwarding packets over an OpenFlow connec‐
       tion. It is not general-purpose QoS. See the QoS table for  quality  of
       service configuration, and ingress_policing_rate in the Interface table
       for ingress policing configuration.

       controller_queue_size: optional integer, in range 1 to 512
              This sets the maximum size of the queue of packets that need  to
              be sent to this OpenFlow controller. The value must be less than
              512. If not specified the queue size is limited to the value set
              for  the management controller in other_config:controller-queue-
              size if present or 100 packets by default. Note: increasing  the
              queue size might have a negative impact on latency.

       controller_rate_limit: optional integer, at least 100
              The maximum rate at which the switch will forward packets to the
              OpenFlow controller, in packets per second. If no value is spec‐
              ified, rate limiting is disabled.

       controller_burst_limit: optional integer, at least 25
              When  a  high  rate  triggers rate-limiting, Open vSwitch queues
              packets to the controller for each port and  transmits  them  to
              the  controller  at  the  configured rate. This value limits the
              number of queued packets. Ports on a  bridge  share  the  packet
              queue fairly.

              This value has no effect unless controller_rate_limit is config‐
              ured. The current default when this value is  not  specified  is
              one-quarter  of  controller_rate_limit, meaning that queuing can
              delay forwarding a packet to the controller by up to 250 ms.

     Controller Rate Limiting Statistics:

       These values report the effects of rate limiting. Their values are rel‐
       ative to establishment of the most recent OpenFlow connection, or since
       rate limiting was enabled, whichever happened more recently. Each  con‐
       sists  of  two values, one with TYPE replaced by miss for rate limiting
       flow table misses, and the other with TYPE replaced by action for  rate
       limiting packets sent by OpenFlow actions.

       These  statistics  are  reported  only when controller rate limiting is
       enabled.

       status : packet-in-TYPE-bypassed: optional string, containing an  inte‐
       ger, at least 0
              Number of packets sent directly to the controller, without queu‐
              ing, because the rate did not exceed the configured maximum.

       status : packet-in-TYPE-queued: optional string, containing an integer,
       at least 0
              Number of packets added to the queue to send later.

       status  :  packet-in-TYPE-dropped: optional string, containing an inte‐
       ger, at least 0
              Number of packets added to the queue that were later dropped due
              to  overflow. This value is less than or equal to status:packet-
              in-TYPE-queued.

       status : packet-in-TYPE-backlog: optional string, containing  an  inte‐
       ger, at least 0
              Number   of  packets  currently  queued.  The  other  statistics
              increase monotonically, but this one fluctuates  between  0  and
              the controller_burst_limit as conditions change.

     Additional In-Band Configuration:

       These  values  are considered only in in-band control mode (see connec‐
       tion_mode).

       When multiple controllers are configured  on  a  single  bridge,  there
       should  be only one set of unique values in these columns. If different
       values are set for these columns in different controllers,  the  effect
       is unspecified.

       local_ip: optional string
              The   IP   address   to   configure  on  the  local  port,  e.g.
              192.168.0.123. If this value is unset,  then  local_netmask  and
              local_gateway are ignored.

       local_netmask: optional string
              The   IP   netmask   to   configure  on  the  local  port,  e.g.
              255.255.255.0. If local_ip is set but this value is unset,  then
              the  default  is chosen based on whether the IP address is class
              A, B, or C.

       local_gateway: optional string
              The IP address of the gateway to configure on the local port, as
              a string, e.g. 192.168.0.1. Leave this column unset if this net‐
              work has no gateway.

     Controller Status:

       is_connected: boolean
              true if currently connected to this controller, false otherwise.

       role: optional string, one of master, other, or slave
              The level of authority this controller  has  on  the  associated
              bridge. Possible values are:

              other  Allows the controller access to all OpenFlow features.

              master Equivalent to other, except that there may be at most one
                     such controller at a time. If a given controller promotes
                     itself  to  this  role, ovs-vswitchd demotes any existing
                     controller with the role to slave.

              slave  Allows the controller read-only access to  OpenFlow  fea‐
                     tures. Attempts to modify the flow table will be rejected
                     with  an  error.  Such   controllers   do   not   receive
                     OFPT_PACKET_IN or OFPT_FLOW_REMOVED messages, but they do
                     receive OFPT_PORT_STATUS messages.

       status : last_error: optional string
              A human-readable description of the last error on the connection
              to  the  controller;  i.e.  strerror(errno). This key will exist
              only if an error has occurred.

       status : state: optional string, one of  ACTIVE,  BACKOFF,  CONNECTING,
       IDLE, or VOID
              The state of the connection to the controller:

              VOID   Connection is disabled.

              BACKOFF
                     Attempting to reconnect at an increasing period.

              CONNECTING
                     Attempting to connect.

              ACTIVE Connected, remote host responsive.

              IDLE   Connection is idle. Waiting for response to keep-alive.

              These  values  may  change in the future. They are provided only
              for human consumption.

       status : sec_since_connect: optional string, containing an integer,  at
       least 0
              The  amount of time since this controller last successfully con‐
              nected to the switch (in seconds). Value is empty if  controller
              has never successfully connected.

       status  : sec_since_disconnect: optional string, containing an integer,
       at least 1
              The amount of time since this controller last disconnected  from
              the  switch (in seconds). Value is empty if controller has never
              disconnected.

     Connection Parameters:

       Additional configuration for a connection between  the  controller  and
       the Open vSwitch.

       other_config : dscp: optional string, containing an integer
              The  Differentiated Service Code Point (DSCP) is specified using
              6 bits in the Type of Service (TOS) field in the IP header. DSCP
              provides a mechanism to classify the network traffic and provide
              Quality of Service (QoS) on IP networks. The DSCP  value  speci‐
              fied  here  is used when establishing the connection between the
              controller and the Open vSwitch. If no  value  is  specified,  a
              default  value of 48 is chosen. Valid DSCP values must be in the
              range 0 to 63.

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

       other_config: map of string-string pairs

Manager TABLE
       Configuration  for  a  database  connection to an Open vSwitch database
       (OVSDB) client.

       This   table   primarily   configures   the   Open   vSwitch   database
       (ovsdb-server),  not the Open vSwitch switch (ovs-vswitchd). The switch
       does read the table to determine what connections should be treated  as
       in-band.

       The  Open vSwitch database server can initiate and maintain active con‐
       nections to remote clients. It can also  listen  for  database  connec‐
       tions.

   Summary:
       Core Features:
         target                      string (must be unique within table)
         connection_mode             optional   string,   either   in-band  or
                                     out-of-band
       Client Failure Detection and Handling:
         max_backoff                 optional integer, at least 1,000
         inactivity_probe            optional integer
       Status:
         is_connected                boolean
         status : last_error         optional string
         status : state              optional string, one of ACTIVE,  BACKOFF,
                                     CONNECTING, IDLE, or VOID
         status : sec_since_connect  optional  string,  containing an integer,
                                     at least 0
         status : sec_since_disconnect
                                     optional string, containing  an  integer,
                                     at least 0
         status : locks_held         optional string
         status : locks_waiting      optional string
         status : locks_lost         optional string
         status : n_connections      optional  string,  containing an integer,
                                     at least 2
         status : bound_port         optional string, containing an integer
       Connection Parameters:
         other_config : dscp         optional string, containing an integer
       Common Columns:
         external_ids                map of string-string pairs
         other_config                map of string-string pairs

   Details:
     Core Features:

       target: string (must be unique within table)
              Connection method for managers.

              The following connection methods are currently supported:

              ssl:host[:port]
                     The specified SSL port on the host  at  the  given  host,
                     which  can  either  be  a DNS name (if built with unbound
                     library)  or  an  IP  address.  The  ssl  column  in  the
                     Open_vSwitch  table  must point to a valid SSL configura‐
                     tion when this form is used.

                     If port is not specified, it defaults to 6640.

                     SSL support is an optional feature  that  is  not  always
                     built as part of Open vSwitch.

              tcp:host[:port]
                     The  specified  TCP  port  on the host at the given host,
                     which can either be a DNS name  (if  built  with  unbound
                     library)  or  an IP address (IPv4 or IPv6). If host is an
                     IPv6  address,  wrap  it   in   square   brackets,   e.g.
                     tcp:[::1]:6640.

                     If port is not specified, it defaults to 6640.

              pssl:[port][:host]
                     Listens  for  SSL  connections on the specified TCP port.
                     Specify 0 for  port  to  have  the  kernel  automatically
                     choose  an available port. If host, which can either be a
                     DNS name  (if  built  with  unbound  library)  or  an  IP
                     address, is specified, then connections are restricted to
                     the resolved or specified local IP address  (either  IPv4
                     or  IPv6  address).  If  host is an IPv6 address, wrap in
                     square brackets, e.g. pssl:6640:[::1].  If  host  is  not
                     specified  then  it  listens  only on IPv4 (but not IPv6)
                     addresses. The ssl column in the Open_vSwitch table  must
                     point  to  a  valid  SSL  configuration when this form is
                     used.

                     If port is not specified, it defaults to 6640.

                     SSL support is an optional feature  that  is  not  always
                     built as part of Open vSwitch.

              ptcp:[port][:host]
                     Listens  for connections on the specified TCP port. Spec‐
                     ify 0 for port to have the kernel automatically choose an
                     available  port.  If host, which can either be a DNS name
                     (if built with unbound library)  or  an  IP  address,  is
                     specified,   then   connections  are  restricted  to  the
                     resolved or specified local IP address  (either  IPv4  or
                     IPv6  address).  If  host  is an IPv6 address, wrap it in
                     square brackets, e.g. ptcp:6640:[::1].  If  host  is  not
                     specified then it listens only on IPv4 addresses.

                     If port is not specified, it defaults to 6640.

              When multiple managers are configured, the target values must be
              unique. Duplicate target values yield unspecified results.

       connection_mode: optional string, either in-band or out-of-band
              If it is specified, this setting must be one  of  the  following
              strings  that  describes  how  Open  vSwitch contacts this OVSDB
              client over the network:

              in-band
                     In this mode, this connection’s traffic  travels  over  a
                     bridge  managed  by Open vSwitch. With this setting, Open
                     vSwitch allows traffic to and from the client  regardless
                     of  the  contents of the OpenFlow flow table. (Otherwise,
                     Open vSwitch would  never  be  able  to  connect  to  the
                     client,  because  it  did  not have a flow to enable it.)
                     This is the most common connection mode because it is not
                     necessary to maintain two independent networks.

              out-of-band
                     In this mode, the client’s traffic uses a control network
                     separate from that managed by Open vSwitch, that is, Open
                     vSwitch  does  not  use any of its own network devices to
                     communicate with the client. The control network must  be
                     configured  separately,  before  or after ovs-vswitchd is
                     started.

              If not specified, the default is implementation-specific.

     Client Failure Detection and Handling:

       max_backoff: optional integer, at least 1,000
              Maximum  number  of  milliseconds  to  wait  between  connection
              attempts. Default is implementation-specific.

       inactivity_probe: optional integer
              Maximum number of milliseconds of idle time on connection to the
              client before sending  an  inactivity  probe  message.  If  Open
              vSwitch  does  not communicate with the client for the specified
              number of seconds, it will send a probe. If a  response  is  not
              received  for  the  same additional amount of time, Open vSwitch
              assumes the connection has been broken and  attempts  to  recon‐
              nect.  Default is implementation-specific. A value of 0 disables
              inactivity probes.

     Status:

       Key-value pair of is_connected is always updated. Other key-value pairs
       in the status columns may be updated depends on the target type.

       When target specifies a connection method that listens for inbound con‐
       nections (e.g. ptcp: or punix:), both  n_connections  and  is_connected
       may also be updated while the remaining key-value pairs are omitted.

       On  the  other  hand, when target specifies an outbound connection, all
       key-value pairs may be updated, except  the  above-mentioned  two  key-
       value  pairs associated with inbound connection targets. They are omit‐
       ted.

       is_connected: boolean
              true if currently connected to this manager, false otherwise.

       status : last_error: optional string
              A human-readable description of the last error on the connection
              to  the  manager; i.e. strerror(errno). This key will exist only
              if an error has occurred.

       status : state: optional string, one of  ACTIVE,  BACKOFF,  CONNECTING,
       IDLE, or VOID
              The state of the connection to the manager:

              VOID   Connection is disabled.

              BACKOFF
                     Attempting to reconnect at an increasing period.

              CONNECTING
                     Attempting to connect.

              ACTIVE Connected, remote host responsive.

              IDLE   Connection is idle. Waiting for response to keep-alive.

              These  values  may  change in the future. They are provided only
              for human consumption.

       status : sec_since_connect: optional string, containing an integer,  at
       least 0
              The  amount  of  time  since this manager last successfully con‐
              nected to the database (in seconds). Value is empty  if  manager
              has never successfully connected.

       status  : sec_since_disconnect: optional string, containing an integer,
       at least 0
              The amount of time since this manager last disconnected from the
              database  (in seconds). Value is empty if manager has never dis‐
              connected.

       status : locks_held: optional string
              Space-separated list of the names of OVSDB locks that  the  con‐
              nection  holds.  Omitted  if  the  connection  does not hold any
              locks.

       status : locks_waiting: optional string
              Space-separated list of the names of OVSDB locks that  the  con‐
              nection  is currently waiting to acquire. Omitted if the connec‐
              tion is not waiting for any locks.

       status : locks_lost: optional string
              Space-separated list of the names of OVSDB locks that  the  con‐
              nection  has  had  stolen by another OVSDB client. Omitted if no
              locks have been stolen from this connection.

       status : n_connections: optional  string,  containing  an  integer,  at
       least 2
              When  target  specifies  a  connection  method  that listens for
              inbound connections (e.g. ptcp: or pssl:) and more than one con‐
              nection  is  actually  active, the value is the number of active
              connections. Otherwise, this key-value pair is omitted.

       status : bound_port: optional string, containing an integer
              When target is ptcp: or pssl:, this is the TCP port on which the
              OVSDB  server  is  listening.  (This is particularly useful when
              target specifies a port of 0, allowing the kernel to choose  any
              available port.)

     Connection Parameters:

       Additional  configuration  for a connection between the manager and the
       Open vSwitch Database.

       other_config : dscp: optional string, containing an integer
              The Differentiated Service Code Point (DSCP) is specified  using
              6 bits in the Type of Service (TOS) field in the IP header. DSCP
              provides a mechanism to classify the network traffic and provide
              Quality  of  Service (QoS) on IP networks. The DSCP value speci‐
              fied here is used when establishing the connection  between  the
              manager  and  the  Open  vSwitch.  If  no  value is specified, a
              default value of 48 is chosen. Valid DSCP values must be in  the
              range 0 to 63.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

       other_config: map of string-string pairs

NetFlow TABLE
       A NetFlow target. NetFlow is  a  protocol  that  exports  a  number  of
       details about terminating IP flows, such as the principals involved and
       duration.

   Summary:
       targets                       set of 1 or more strings
       engine_id                     optional integer, in range 0 to 255
       engine_type                   optional integer, in range 0 to 255
       active_timeout                integer, at least -1
       add_id_to_interface           boolean
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       targets: set of 1 or more strings
              NetFlow targets in the form ip:port. The ip  must  be  specified
              numerically, not as a DNS name.

       engine_id: optional integer, in range 0 to 255
              Engine ID to use in NetFlow messages. Defaults to datapath index
              if not specified.

       engine_type: optional integer, in range 0 to 255
              Engine type to use in NetFlow  messages.  Defaults  to  datapath
              index if not specified.

       active_timeout: integer, at least -1
              The  interval  at  which NetFlow records are sent for flows that
              are still active, in seconds. A value of 0 requests the  default
              timeout  (currently  600 seconds); a value of -1 disables active
              timeouts.

              The NetFlow passive timeout, for flows that become inactive,  is
              not  configurable.  It  will  vary depending on the Open vSwitch
              version, the forms and contents of the OpenFlow flow tables, CPU
              and  memory usage, and network activity. A typical passive time‐
              out is about a second.

       add_id_to_interface: boolean
              If this column’s value is false, the ingress and  egress  inter‐
              face  fields  of  NetFlow flow records are derived from OpenFlow
              port numbers. When it is true, the 7 most  significant  bits  of
              these fields will be replaced by the least significant 7 bits of
              the engine id. This is useful because many NetFlow collectors do
              not  expect  multiple  switches  to be sending messages from the
              same host, so they do not store  the  engine  information  which
              could be used to disambiguate the traffic.

              When  this  option  is  enabled, a maximum of 508 ports are sup‐
              ported.

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

Datapath TABLE
       Configuration for a datapath within Open_vSwitch.

       A  datapath  is  responsible  for providing the packet handling in Open
       vSwitch. There are two primary datapath implementations  used  by  Open
       vSwitch:  kernel  and  userspace.  Kernel  datapath implementations are
       available for Linux and Hyper-V, and selected as system  in  the  data‐
       path_type column of the Bridge table. The userspace datapath is used by
       DPDK and AF-XDP, and is selected as netdev in the datapath_type  column
       of the Bridge table.

       A  datapath  of a particular type is shared by all the bridges that use
       that datapath. Thus, configurations applied to this  table  affect  all
       bridges that use this datapath.

   Summary:
       datapath_version              string
       ct_zones                      map  of  integer-CT_Zone  pairs,  key  in
                                     range 0 to 65,535
       Capabilities:
         capabilities : max_vlan_headers
                                     optional string, containing  an  integer,
                                     at least 0
         capabilities : recirc       optional string, either true or false
         capabilities : lb_output_action
                                     optional string, either true or false
         Connection-Tracking Capabilities:
            capabilities : ct_state  optional string, either true or false
            capabilities : ct_state_nat
                                     optional string, either true or false
            capabilities : ct_zone   optional string, either true or false
            capabilities : ct_mark   optional string, either true or false
            capabilities : ct_label  optional string, either true or false
            capabilities : ct_orig_tuple
                                     optional string, either true or false
            capabilities : ct_orig_tuple6
                                     optional string, either true or false
         capabilities : masked_set_action
                                     optional string, either true or false
         capabilities : tnl_push_pop
                                     optional string, either true or false
         capabilities : ufid         optional string, either true or false
         capabilities : trunc        optional string, either true or false
         capabilities : nd_ext       optional string, either true or false
         Clone Actions:
            capabilities : clone     optional string, either true or false
            capabilities : sample_nesting
                                     optional  string,  containing an integer,
                                     at least 0
         capabilities : ct_eventmask
                                     optional string, either true or false
         capabilities : ct_clear     optional string, either true or false
         capabilities : max_hash_alg
                                     optional string, containing  an  integer,
                                     at least 0
         capabilities : check_pkt_len
                                     optional string, either true or false
         capabilities : ct_timeout   optional string, either true or false
         capabilities : explicit_drop_action
                                     optional string, either true or false
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       datapath_version: string
              Reports  the version number of the Open vSwitch datapath in use.
              This allows management software to detect and report  discrepan‐
              cies  between Open vSwitch userspace and datapath versions. (The
              ovs_version column in the Open_vSwitch reports the Open  vSwitch
              userspace version.) The version reported depends on the datapath
              in use:

              ·      When the kernel  module  included  in  the  Open  vSwitch
                     source tree is used, this column reports the Open vSwitch
                     version from which the module was taken.

              ·      When the kernel module that is part of the upstream Linux
                     kernel is used, this column reports <unknown>.

              ·      When  the datapath is built into the ovs-vswitchd binary,
                     this column reports <built-in>. A built-in datapath is by
                     definition  the  same  version  as  the  rest of the Open
                     vSwitch userspace.

              ·      Other datapaths (such as  the  Hyper-V  kernel  datapath)
                     currently report <unknown>.

              A  version  discrepancy between ovs-vswitchd and the datapath in
              use is not normally cause for alarm.  The  Open  vSwitch  kernel
              datapaths for Linux and Hyper-V, in particular, are designed for
              maximum inter-version compatibility: any userspace version works
              with with any kernel version. Some reasons do exist to insist on
              particular user/kernel pairings. First,  newer  kernel  versions
              add new features, that can only be used by new-enough userspace,
              e.g. VXLAN tunneling requires certain minimal userspace and ker‐
              nel  versions. Second, as an extension to the first reason, some
              newer kernel versions add new features for enhancing performance
              that only new-enough userspace versions can take advantage of.

       ct_zones: map of integer-CT_Zone pairs, key in range 0 to 65,535
              Configuration for connection tracking zones. Each pair maps from
              a zone id to a configuration for that zone. Zone  0  applies  to
              the default zone (ie, the one used if a zone is not specified in
              connection tracking-related OpenFlow matches and actions).

     Capabilities:

       The capabilities column reports a datapath’s features. For  the  netdev
       datapath,  the  capabilities  are  fixed  for  a  given version of Open
       vSwitch because this datapath is built into  the  ovs-vswitchd  binary.
       The Linux kernel and Windows and other datapaths, which are external to
       OVS userspace, can vary in version and capabilities independently  from
       ovs-vswitchd.

       Some  of these features indicate whether higher-level Open vSwitch fea‐
       tures are available. For example,  OpenFlow  features  for  connection-
       tracking  are available only when capabilities:ct_state is true. A con‐
       troller that wishes to determine whether a feature is supported  could,
       therefore, consult the relevant capabilities in this table. However, as
       a general rule, it is better for a controller to try to use the higher-
       level feature and use the result as an indication of support, since the
       low-level capabilities are more likely to  shift  over  time  than  the
       high-level features that rely on them.

       capabilities  :  max_vlan_headers: optional string, containing an inte‐
       ger, at least 0
              Number of 802.1q VLAN headers  supported  by  the  datapath,  as
              probed  by  the ovs-vswitchd slow path. If the datapath supports
              more VLAN headers than the slow  path,  this  reports  the  slow
              path’s  limit.  The  value  of  other-config:vlan-limit  in  the
              Open_vSwitch table does not influence the number reported here.

       capabilities : recirc: optional string, either true or false
              If this is  true,  then  the  datapath  supports  recirculation,
              specifically   OVS_KEY_ATTR_RECIRC_ID.   Recirculation   enables
              higher performance for MPLS  and  active-active  load  balancing
              bonding modes.

       capabilities : lb_output_action: optional string, either true or false
              If  this  is true, then the datapath supports optimized balance-
              tcp bond mode. This capability replaces existing hash and recirc
              actions  with  new  action lb_output and avoids recirculation of
              packet in datapath. It is supported only  for  balance-tcp  bond
              mode  in netdev datapath. The new action gives higer performance
              by using bond buckets instead of post  recirculation  flows  for
              selection of slave port from bond. By default this new action is
              disabled, however it can be enabled by setting  other-config:lb-
              output-action in Port table.

     Connection-Tracking Capabilities:

       These  capabilities are granular because Open vSwitch and its datapaths
       added support for connection tracking over several releases, with  fea‐
       tures added individually over that time.

       capabilities : ct_state: optional string, either true or false
              If  true,  datapath  supports OVS_KEY_ATTR_CT_STATE, which indi‐
              cates support for the bits in the OpenFlow ct_state  field  (see
              ovs-fields(7))  other  than snat and dnat, which have a separate
              capability.

              If this is false, the  datapath  does  not  support  connection-
              tracking  at all and the remaining connection-tracking capabili‐
              ties should all be false. In this case, Open vSwitch will reject
              flows that match on the ct_state field or use the ct action.

       capabilities : ct_state_nat: optional string, either true or false
              If  true,  it means that the datapath supports the snat and dnat
              flags in the OpenFlow ct_state field.  The  ct_state  capability
              must be true for this to make sense.

              If  false, Open vSwitch will reject flows that match on the snat
              or dnat bits in ct_state or use nat in the ct action.

       capabilities : ct_zone: optional string, either true or false
              If true, datapath supports OVS_KEY_ATTR_CT_ZONE. If false,  Open
              vSwitch  rejects  flows  that match on the ct_zone field or that
              specify a nonzero zone or a zone field on the ct action.

       capabilities : ct_mark: optional string, either true or false
              If true, datapath supports OVS_KEY_ATTR_CT_MARK. If false,  Open
              vSwitch  rejects  flows  that match on the ct_mark field or that
              set ct_mark in the ct action.

       capabilities : ct_label: optional string, either true or false
              If true, datapath supports OVS_KEY_ATTR_CT_LABEL. If false, Open
              vSwitch  rejects  flows that match on the ct_label field or that
              set ct_label in the ct action.

       capabilities : ct_orig_tuple: optional string, either true or false
              If true, the datapath supports matching  the  5-tuple  from  the
              connection’s original direction for IPv4 traffic. If false, Open
              vSwitch rejects flows that match on ct_nw_src or ct_nw_dst, that
              use  the ct feature of the resubmit action, or the force keyword
              in the ct action. (The latter isn’t tied to connection  tracking
              support  of  original tuples in any technical way. They are con‐
              flated because all current datapaths implemented  the  two  fea‐
              tures at the same time.)

              If  this  and  capabilities:ct_orig_tuple6  are both false, Open
              vSwitch rejects flows that match on ct_nw_proto,  ct_tp_src,  or
              ct_tp_dst.

       capabilities : ct_orig_tuple6: optional string, either true or false
              If  true,  the  datapath  supports matching the 5-tuple from the
              connection’s original direction for IPv6 traffic. If false, Open
              vSwitch rejects flows that match on ct_ipv6_src or ct_ipv6_dst.

       capabilities : masked_set_action: optional string, either true or false
              True if the datapath supports masked data in OVS_ACTION_ATTR_SET
              actions.  Masked  data  can  improve  performance  by   allowing
              megaflows to match on fewer fields.

       capabilities : tnl_push_pop: optional string, either true or false
              True  if the datapath supports tnl_push and pop actions. This is
              a prerequisite for a datapath to support native tunneling.

       capabilities : ufid: optional string, either true or false
              True if the datapath supports OVS_FLOW_ATTR_UFID.  UFID  support
              improves  revalidation  performance  by  transferring  less data
              between the slow path and the datapath.

       capabilities : trunc: optional string, either true or false
              True if the datapath supports OVS_ACTION_ATTR_TRUNC  action.  If
              false,  the  output action with packet truncation requires every
              packet to be sent to the Open vSwitch slow path, which is likely
              to make it too slow for mirroring traffic in bulk.

       capabilities : nd_ext: optional string, either true or false
              True  if  the  datapath  supports  OVS_KEY_ATTR_ND_EXTENSIONS to
              match on ICMPv6  "ND  reserved"  and  "ND  option  type"  header
              fields.  If  false, the datapath reports error if the feature is
              used.

     Clone Actions:

       When Open vSwitch translates actions from OpenFlow  into  the  datapath
       representation,  some  of the datapath actions may modify the packet or
       have other side effects that later datapath  actions  can’t  undo.  The
       OpenFlow   ct,   meter,  output  with  truncation,  encap,  decap,  and
       dec_nsh_ttl actions fall into this category. Often, this is not a prob‐
       lem because nothing later on needs the original packet.

       Such actions can, however, occur in circumstances where the translation
       does require the original  packet.  For  example,  an  OpenFlow  output
       action  might direct a packet to a patch port, which might in turn lead
       to a ct action that NATs the packet (which cannot be undone), and  then
       afterward  when control flow pops back across the patch port some other
       action might need to act on the original packet.

       Open vSwitch has two  different  ways  to  implement  this  ``save  and
       restore’’  via  datapath actions. These capabilities indicate which one
       Open vSwitch will choose. When neither is available, Open vSwitch  sim‐
       ply fails in situations that require this feature.

       capabilities : clone: optional string, either true or false
              True if the datapath supports OVS_ACTION_ATTR_CLONE action. This
              is the preferred option for saving and restoring packets,  since
              it is intended for the purpose, but old datapaths do not support
              it. Open vSwitch will use it whenever it is available.

              (The  OpenFlow  clone   action   does   not   always   yield   a
              OVS_ACTION_ATTR_CLONE  action. It only does so when the datapath
              supports it and the clone brackets actions that otherwise cannot
              be undone.)

       capabilities  : sample_nesting: optional string, containing an integer,
       at least 0
              Maximum  level  of  nesting  allowed  by  OVS_ACTION_ATTR_SAMPLE
              action.  Open vSwitch misuses this action for saving and restor‐
              ing packets when the datapath supports more  than  3  levels  of
              nesting and OVS_ACTION_ATTR_CLONE is not available.

       capabilities : ct_eventmask: optional string, either true or false
              True  if the datapath’s OVS_ACTION_ATTR_CT action implements the
              OVS_CT_ATTR_EVENTMASK attribute. When this is true, Open vSwitch
              uses  the  event  mask  feature  to  limit  the  kinds of events
              reported  to  conntrack  update  listeners.  When  Open  vSwitch
              doesn’t  limit  the  event  mask,  listeners  receive reports of
              numerous usually unimportant events, such as TCP  state  machine
              changes, which can waste CPU time.

       capabilities : ct_clear: optional string, either true or false
              True  if  the datapath supports OVS_ACTION_ATTR_CT_CLEAR action.
              If false, the OpenFlow ct_clear action  has  no  effect  on  the
              datapath.

       capabilities : max_hash_alg: optional string, containing an integer, at
       least 0
              Highest supported dp_hash algorithm. This allows Open vSwitch to
              avoid  requesting  a packet hash that the datapath does not sup‐
              port.

       capabilities : check_pkt_len: optional string, either true or false
              True if the datapath supports OVS_ACTION_ATTR_CHECK_PKT_LEN.  If
              false,  Open  vSwitch  implements the check_pkt_larger action by
              sending every packet through the Open vSwitch slow  path,  which
              is likely to make it too slow for handling traffic in bulk.

       capabilities : ct_timeout: optional string, either true or false
              True   if  the  datapath  supports  OVS_CT_ATTR_TIMEOUT  in  the
              OVS_ACTION_ATTR_CT action. If false, Open vswitch cannot  imple‐
              ment  timeout  policies  based  on connection tracking zones, as
              configured through the CT_Timeout_Policy table.

       capabilities : explicit_drop_action: optional string,  either  true  or
       false
              True  if  the  datapath supports OVS_ACTION_ATTR_DROP. If false,
              explicit drop action will not be sent to the datapath.

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

CT_Zone TABLE
       Connection tracking zone configuration

   Summary:
       timeout_policy                optional CT_Timeout_Policy
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       timeout_policy: optional CT_Timeout_Policy
              Connection  tracking  timeout policy for this zone. If a timeout
              policy is not specified, it defaults to the  timeout  policy  in
              the system.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

CT_Timeout_Policy TABLE
       Connection tracking timeout policy configuration

   Summary:
       Timeouts:
         timeouts                    map of string-integer pairs, key  one  of
                                     icmp_first,     icmp_reply,    tcp_close,
                                     tcp_close_wait,          tcp_established,
                                     tcp_fin_wait,  tcp_last_ack, tcp_retrans‐
                                     mit,     tcp_syn_recv,     tcp_syn_sent2,
                                     tcp_syn_sent,  tcp_time_wait,  tcp_unack,
                                     udp_first, udp_multiple,  or  udp_single,
                                     value in range 0 to 4,294,967,295
         TCP Timeouts:
            timeouts : tcp_syn_sent  optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : tcp_syn_recv  optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : tcp_established
                                     optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : tcp_fin_wait  optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : tcp_close_wait
                                     optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : tcp_last_ack  optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : tcp_time_wait optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : tcp_close     optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : tcp_syn_sent2 optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : tcp_retransmit
                                     optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : tcp_unack     optional   integer,   in   range   0   to
                                     4,294,967,295
         UDP Timeouts:
            timeouts : udp_first     optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : udp_single    optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : udp_multiple  optional   integer,   in   range   0   to
                                     4,294,967,295
         ICMP Timeouts:
            timeouts : icmp_first    optional   integer,   in   range   0   to
                                     4,294,967,295
            timeouts : icmp_reply    optional   integer,   in   range   0   to
                                     4,294,967,295
       Common Columns:
         external_ids                map of string-string pairs

   Details:
     Timeouts:

       timeouts:   map   of  string-integer  pairs,  key  one  of  icmp_first,
       icmp_reply, tcp_close, tcp_close_wait,  tcp_established,  tcp_fin_wait,
       tcp_last_ack,      tcp_retransmit,     tcp_syn_recv,     tcp_syn_sent2,
       tcp_syn_sent, tcp_time_wait,  tcp_unack,  udp_first,  udp_multiple,  or
       udp_single, value in range 0 to 4,294,967,295
              The  timeouts  column contains key-value pairs used to configure
              connection tracking timeouts in a datapath. Key-value pairs that
              are  not  supported by a datapath are ignored. The timeout value
              is in seconds.

     TCP Timeouts:

       timeouts : tcp_syn_sent: optional integer, in range 0 to 4,294,967,295
              The timeout for the connection after the first  TCP  SYN  packet
              has been seen by conntrack.

       timeouts : tcp_syn_recv: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after the first TCP SYN-ACK packet
              has been seen by conntrack.

       timeouts  :  tcp_established:  optional  integer,   in   range   0   to
       4,294,967,295
              The  timeout  of  the  connection  after the connection has been
              fully established.

       timeouts : tcp_fin_wait: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after the first TCP FIN packet has
              been seen by conntrack.

       timeouts   :   tcp_close_wait:   optional   integer,   in  range  0  to
       4,294,967,295
              The timeout of the connection after the first TCP ACK packet has
              been seen after it receives TCP FIN packet. This timeout is only
              supported by the Linux kernel datapath.

       timeouts : tcp_last_ack: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after TCP FIN  packets  have  been
              seen  by  conntrack  from  both directions. This timeout is only
              supported by the Linux kernel datapath.

       timeouts : tcp_time_wait: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after conntrack has seen  the  TCP
              ACK packet for the second TCP FIN packet.

       timeouts : tcp_close: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after the first TCP RST packet has
              been seen by conntrack.

       timeouts : tcp_syn_sent2: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection when only a  TCP  SYN  packet  has
              been seen by conntrack from both directions (simultaneous open).
              This timeout is only supported by the Linux kernel datapath.

       timeouts  :  tcp_retransmit:  optional   integer,   in   range   0   to
       4,294,967,295
              The timeout of the connection when it exceeds the maximum number
              of retransmissions. This timeout is only supported by the  Linux
              kernel datapath.

       timeouts : tcp_unack: optional integer, in range 0 to 4,294,967,295
              The  timeout  of  the  connection when non-SYN packets create an
              established connection in TCP loose tracking mode. This  timeout
              is only supported by the Linux kernel datapath.

     UDP Timeouts:

       timeouts : udp_first: optional integer, in range 0 to 4,294,967,295
              The  timeout  of  the  connection after the first UDP packet has
              been seen by conntrack. This timeout is only  supported  by  the
              userspace datapath.

       timeouts : udp_single: optional integer, in range 0 to 4,294,967,295
              The  timeout  of  the  connection  when  conntrack only seen UDP
              packet from the source host, but the destination host has  never
              sent one back.

       timeouts : udp_multiple: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection when UDP packets have been seen in
              both directions.

     ICMP Timeouts:

       timeouts : icmp_first: optional integer, in range 0 to 4,294,967,295
              The timeout of the connection after the first  ICMP  packet  has
              been seen by conntrack.

       timeouts : icmp_reply: optional integer, in range 0 to 4,294,967,295
              The  timeout  of the connection when ICMP packets have been seen
              in both  direction.  This  timeout  is  only  supported  by  the
              userspace datapath.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

SSL TABLE
       SSL configuration for an Open_vSwitch.

   Summary:
       private_key                   string
       certificate                   string
       ca_cert                       string
       bootstrap_ca_cert             boolean
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       private_key: string
              Name of a PEM file  containing  the  private  key  used  as  the
              switch’s identity for SSL connections to the controller.

       certificate: string
              Name  of a PEM file containing a certificate, signed by the cer‐
              tificate authority (CA) used by the controller and manager, that
              certifies  the  switch’s  private key, identifying a trustworthy
              switch.

       ca_cert: string
              Name of a PEM file containing the CA certificate used to  verify
              that the switch is connected to a trustworthy controller.

       bootstrap_ca_cert: boolean
              If  set to true, then Open vSwitch will attempt to obtain the CA
              certificate from the controller on its first SSL connection  and
              save  it  to  the  named  PEM file. If it is successful, it will
              immediately drop the connection and reconnect, and from then  on
              all  SSL  connections  must  be  authenticated  by a certificate
              signed by the CA certificate thus obtained. This option  exposes
              the  SSL  connection to a man-in-the-middle attack obtaining the
              initial CA certificate. It may still be  useful  for  bootstrap‐
              ping.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

sFlow TABLE
       A set of sFlow(R) targets. sFlow is a protocol for remote monitoring of
       switches.

   Summary:
       agent                         optional string
       header                        optional integer
       polling                       optional integer
       sampling                      optional integer
       targets                       set of 1 or more strings
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       agent: optional string
              Determines  the  agent address, that is, the IP address reported
              to collectors as the source of the sFlow data. It may be  an  IP
              address or the name of a network device. In the latter case, the
              network device’s IP address is used,

              If not specified, the agent device is  figured  from  the  first
              target  address and the routing table. If the routing table does
              not contain a route to the target, the IP  address  defaults  to
              the local_ip in the collector’s Controller.

              If an agent IP address cannot be determined, sFlow is disabled.

       header: optional integer
              Number of bytes of a sampled packet to send to the collector. If
              not specified, the default is 128 bytes.

       polling: optional integer
              Polling rate in seconds to send port statistics to  the  collec‐
              tor. If not specified, defaults to 30 seconds.

       sampling: optional integer
              Rate  at which packets should be sampled and sent to the collec‐
              tor. If not specified, defaults to 400, which means one  out  of
              400 packets, on average, will be sent to the collector.

       targets: set of 1 or more strings
              sFlow targets in the form ip:port.

     Common Columns:

       The  overall purpose of these columns is described under Common Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

IPFIX TABLE
       Configuration for sending packets to IPFIX collectors.

       IPFIX is a protocol that exports a number of details about  flows.  The
       IPFIX  implementation in Open vSwitch samples packets at a configurable
       rate, extracts flow information from those packets,  optionally  caches
       and  aggregates  the  flow  information, and sends the result to one or
       more collectors.

       IPFIX in Open vSwitch can be configured two different ways:

              ·      With per-bridge sampling,  Open  vSwitch  performs  IPFIX
                     sampling automatically on all packets that pass through a
                     bridge. To configure per-bridge sampling, create an IPFIX
                     record and point a Bridge table’s ipfix column to it. The
                     Flow_Sample_Collector_Set table  is  not  used  for  per-
                     bridge sampling.

              ·      With  flow-based sampling, sample actions in the OpenFlow
                     flow table drive IPFIX sampling. See ovs-actions(7) for a
                     description of the sample action.

                     Flow-based sampling also requires database configuration:
                     create a IPFIX record that describes the IPFIX configura‐
                     tion  and  a Flow_Sample_Collector_Set record that points
                     to the Bridge whose flow table holds the  sample  actions
                     and to IPFIX record. The ipfix in the Bridge table is not
                     used for flow-based sampling.

   Summary:
       targets                       set of strings
       cache_active_timeout          optional integer, in range 0 to 4,200
       cache_max_flows               optional   integer,   in   range   0   to
                                     4,294,967,295
       other_config : enable-tunnel-sampling
                                     optional string, either true or false
       other_config : virtual_obs_id optional string
       Per-Bridge Sampling:
         sampling                    optional   integer,   in   range   1   to
                                     4,294,967,295
         obs_domain_id               optional   integer,   in   range   0   to
                                     4,294,967,295
         obs_point_id                optional   integer,   in   range   0   to
                                     4,294,967,295
         other_config : enable-input-sampling
                                     optional string, either true or false
         other_config : enable-output-sampling
                                     optional string, either true or false
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       targets: set of strings
              IPFIX target collectors in the form ip:port.

       cache_active_timeout: optional integer, in range 0 to 4,200
              The maximum period in seconds for which an IPFIX flow record  is
              cached  and  aggregated  before  being  sent.  If not specified,
              defaults to 0. If 0, caching is disabled.

       cache_max_flows: optional integer, in range 0 to 4,294,967,295
              The maximum number of IPFIX flow records that can be cached at a
              time.  If  not  specified,  defaults to 0. If 0, caching is dis‐
              abled.

       other_config : enable-tunnel-sampling: optional string, either true  or
       false
              Set  to  true  to  enable  sampling  and reporting tunnel header
              7-tuples in IPFIX flow records. Tunnel sampling  is  enabled  by
              default.

              The  following  enterprise  entities  report  the sampled tunnel
              info:

              tunnelType:
                     ID: 891, and enterprise ID 6876 (VMware).

                     type: unsigned 8-bit integer.

                     data type semantics: identifier.

                     description: Identifier of the layer  2  network  overlay
                     network  encapsulation  type:  0x01 VxLAN, 0x02 GRE, 0x03
                     LISP, 0x07 GENEVE.

              tunnelKey:
                     ID: 892, and enterprise ID 6876 (VMware).

                     type: variable-length octetarray.

                     data type semantics: identifier.

                     description: Key which is used for identifying  an  indi‐
                     vidual  traffic  flow within a VxLAN (24-bit VNI), GENEVE
                     (24-bit VNI), GRE (32-bit key), or LISP (24-bit  instance
                     ID)  tunnel.  The  key is encoded in this octetarray as a
                     3-, 4-, or 8-byte integer ID in network byte order.

              tunnelSourceIPv4Address:
                     ID: 893, and enterprise ID 6876 (VMware).

                     type: unsigned 32-bit integer.

                     data type semantics: identifier.

                     description: The IPv4 source address  in  the  tunnel  IP
                     packet header.

              tunnelDestinationIPv4Address:
                     ID: 894, and enterprise ID 6876 (VMware).

                     type: unsigned 32-bit integer.

                     data type semantics: identifier.

                     description:  The  IPv4 destination address in the tunnel
                     IP packet header.

              tunnelProtocolIdentifier:
                     ID: 895, and enterprise ID 6876 (VMware).

                     type: unsigned 8-bit integer.

                     data type semantics: identifier.

                     description: The value of the protocol number in the tun‐
                     nel  IP packet header. The protocol number identifies the
                     tunnel IP packet payload type.

              tunnelSourceTransportPort:
                     ID: 896, and enterprise ID 6876 (VMware).

                     type: unsigned 16-bit integer.

                     data type semantics: identifier.

                     description: The source port  identifier  in  the  tunnel
                     transport  header.  For the transport protocols UDP, TCP,
                     and SCTP, this is the source port  number  given  in  the
                     respective header.

              tunnelDestinationTransportPort:
                     ID: 897, and enterprise ID 6876 (VMware).

                     type: unsigned 16-bit integer.

                     data type semantics: identifier.

                     description:  The destination port identifier in the tun‐
                     nel transport header. For the  transport  protocols  UDP,
                     TCP,  and SCTP, this is the destination port number given
                     in the respective header.

              Before Open vSwitch 2.5.90,  other_config:enable-tunnel-sampling
              was  only supported with per-bridge sampling, and ignored other‐
              wise. Open vSwitch 2.5.90 and later support other_config:enable-
              tunnel-sampling for per-bridge and per-flow sampling.

       other_config : virtual_obs_id: optional string
              A  string  that accompanies each IPFIX flow record. Its intended
              use is for the ``virtual observation ID,’’ an  identifier  of  a
              virtual  observation  point  that is locally unique in a virtual
              network. It describes a location in the virtual network where IP
              packets can be observed. The maximum length is 254 bytes. If not
              specified, the field is omitted from the IPFIX flow record.

              The following enterprise entity reports  the  specified  virtual
              observation ID:

              virtualObsID:
                     ID: 898, and enterprise ID 6876 (VMware).

                     type: variable-length string.

                     data type semantics: identifier.

                     description:  A  virtual  observation  domain  ID that is
                     locally unique in a virtual network.

              This feature was introduced in Open vSwitch 2.5.90.

     Per-Bridge Sampling:

       These values affect only per-bridge sampling. See above for a  descrip‐
       tion of the differences between per-bridge and flow-based sampling.

       sampling: optional integer, in range 1 to 4,294,967,295
              The  rate  at  which  packets should be sampled and sent to each
              target collector. If not specified, defaults to 400, which means
              one  out of 400 packets, on average, will be sent to each target
              collector.

       obs_domain_id: optional integer, in range 0 to 4,294,967,295
              The IPFIX Observation Domain ID sent in each  IPFIX  packet.  If
              not specified, defaults to 0.

       obs_point_id: optional integer, in range 0 to 4,294,967,295
              The  IPFIX  Observation Point ID sent in each IPFIX flow record.
              If not specified, defaults to 0.

       other_config : enable-input-sampling: optional string, either  true  or
       false
              By  default,  Open  vSwitch  samples and reports flows at bridge
              port input in IPFIX flow records. Set this column  to  false  to
              disable input sampling.

       other_config  : enable-output-sampling: optional string, either true or
       false
              By default, Open vSwitch samples and  reports  flows  at  bridge
              port  output  in IPFIX flow records. Set this column to false to
              disable output sampling.

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

Flow_Sample_Collector_Set TABLE
       A  set of IPFIX collectors of packet samples generated by OpenFlow sam‐
       ple actions. This table is used only for IPFIX flow-based sampling, not
       for  per-bridge  sampling (see the IPFIX table for a description of the
       two forms).

   Summary:
       id                            integer, in range 0 to 4,294,967,295
       bridge                        Bridge
       ipfix                         optional IPFIX
       Common Columns:
         external_ids                map of string-string pairs

   Details:
       id: integer, in range 0 to 4,294,967,295
              The ID of this collector set, unique among the bridge’s  collec‐
              tor  sets, to be used as the collector_set_id in OpenFlow sample
              actions.

       bridge: Bridge
              The bridge into which OpenFlow sample actions can  be  added  to
              send packet samples to this set of IPFIX collectors.

       ipfix: optional IPFIX
              Configuration  of  the  set of IPFIX collectors to send one flow
              record per sampled packet to.

     Common Columns:

       The overall purpose of these columns is described under Common  Columns
       at the beginning of this document.

       external_ids: map of string-string pairs

AutoAttach TABLE
       Auto  Attach  configuration  within a bridge. The IETF Auto-Attach SPBM
       draft standard describes a compact method of using  IEEE  802.1AB  Link
       Layer  Discovery  Protocol (LLDP) together with a IEEE 802.1aq Shortest
       Path Bridging (SPB) network to automatically attach network devices  to
       individual  services in a SPB network. The intent here is to allow net‐
       work applications and devices using OVS  to  be  able  to  easily  take
       advantage of features offered by industry standard SPB networks.

       Auto  Attach (AA) uses LLDP to communicate between a directly connected
       Auto Attach Client (AAC) and Auto Attach Server (AAS). The LLDP  proto‐
       col  is  extended  to  add two new Type-Length-Value tuples (TLVs). The
       first new TLV supports the ongoing discovery of directly  connected  AA
       correspondents.  Auto Attach operates by regularly transmitting AA dis‐
       covery TLVs between the AA client and AA server.  By  exchanging  these
       discovery messages, both the AAC and AAS learn the system name and sys‐
       tem description of their peer. In the OVS context, OVS operates as  the
       AA  client and the AA server resides on a switch at the edge of the SPB
       network.

       Once AA discovery has been completed the AAC then uses the  second  new
       TLV  to  deliver identifier mappings from the AAC to the AAS. A primary
       feature of Auto Attach is to facilitate the mapping  of  VLANs  defined
       outside the SPB network onto service ids (ISIDs) defined within the SPM
       network. By doing so individual external VLANs can be mapped onto  spe‐
       cific  SPB network services. These VLAN id to ISID mappings can be con‐
       figured and managed locally using new options added  to  the  ovs-vsctl
       command.

       The  Auto  Attach OVS feature does not provide a full implementation of
       the LLDP protocol. Support for the mandatory TLVs  as  defined  by  the
       LLDP  standard  and support for the AA TLV extensions is provided. LLDP
       protocol support in OVS can be enabled or disabled on a  port  by  port
       basis. LLDP support is disabled by default.

   Summary:
       system_name                   string
       system_description            string
       mappings                      map  of  integer-integer  pairs,  key  in
                                     range 0 to 16,777,215, value in  range  0
                                     to 4,095

   Details:
       system_name: string
              The  system_name  string is exported in LLDP messages. It should
              uniquely identify the bridge in the network.

       system_description: string
              The system_description string is exported in LLDP  messages.  It
              should describe the type of software and hardware.

       mappings:  map  of integer-integer pairs, key in range 0 to 16,777,215,
       value in range 0 to 4,095
              A mapping from SPB network Individual Service Identifier  (ISID)
              to VLAN id.



Open vSwitch 2.15.90            DB Schema 8.2.0        ovs-vswitchd.conf.db(5)