ovs-ctl(8)                    Open vSwitch Manual                   ovs-ctl(8)

       ovs-ctl - OVS startup helper script

       ovs-ctl --system-id=random|uuid [options] start
       ovs-ctl stop
       ovs-ctl --system-id=random|uuid [options] restart
       ovs-ctl status
       ovs-ctl version
       ovs-ctl [options] load-kmod
       ovs-ctl --system-id=random|uuid [options] force-reload-kmod
       ovs-ctl     [--protocol=protocol]    [--sport=sport]    [--dport=dport]
       ovs-ctl help | -h | --help
       ovs-ctl --version

       The ovs-ctl program starts,  stops,  and  checks  the  status  of  Open
       vSwitch  daemons.   It  is  not  meant to be invoked directly by system
       administrators but to be called internally by system startup scripts.

       Each of ovs-ctl's commands is described separately below.

The ``start'' command
       The start command starts  Open  vSwitch.   It  performs  the  following

       1.     Loads  the  Open  vSwitch kernel module.  If this fails, and the
              Linux bridge module is loaded but no bridges exist, it tries  to
              unload the bridge module and tries loading the Open vSwitch ker‐
              nel module again.  (This is because the Open vSwitch kernel mod‐
              ule cannot coexist with the Linux bridge module before 2.6.37.)

       The  start command skips the following steps if ovsdb-server is already

       2.     If the Open vSwitch database file does not exist, it creates it.
              If  the  database does exist, but it has an obsolete version, it
              upgrades it to the latest schema.

       3.     Starts ovsdb-server.

       4.     Initializes a few values inside the database.

       5.     If the --delete-bridges option was  used,  deletes  all  of  the
              bridges from the database.

       6.     If  the  --delete-transient-ports  option  was used, deletes all
              ports that have other_config:transient set to true.

       The start command skips the following step if ovs-vswitchd  is  already

       7.     Starts ovs-vswitchd.

       Several  command-line  options  influence the start command's behavior.
       Some form of the following option should ordinarily be specified:

              This specifies a unique system identifier to store  into  exter
              nal-ids:system-id  in the database's Open_vSwitch table.  Remote
              managers that talk to the Open vSwitch database server over net‐
              work  protocols  use this value to identify and distinguish Open
              vSwitch instances, so it should be unique (at least) within  OVS
              instances that will connect to a single controller.

              When random is specified, ovs-ctl will generate a random ID that
              persists from one run to  another  (stored  in  a  file).   When
              another string is specified ovs-ctl uses it literally.

       The following options should be specified if the defaults are not suit‐

              Sets the value to store in the  system-type  and  system-version
              columns,  respectively,  in  the  database's Open_vSwitch table.
              Remote managers may use these values to determine  the  kind  of
              system  to  which  they  are connected (primarily for display to
              human administrators).

              When not specified, ovs-ctl uses values from the  optional  sys
              tem-type.conf  and  system-version.conf files(see section FILES)
              or it uses the lsb_release program, if present, to provide  rea‐
              sonable defaults.

       The following options are also likely to be useful:

              Sets  external-ids:name  to value in the database's Open_vSwitch
              table.  Specifying this option multiple times adds multiple key-
              value pairs.

              Ordinarily  Open vSwitch bridges persist from one system boot to
              the next, as long as the database is preserved.   Some  environ‐
              ments  instead  expect to re-create all of the bridges and other
              configuration state on every boot.  This option  supports  that,
              by deleting all Open vSwitch bridges after starting ovsdb-server
              but before starting ovs-vswitchd.

              Deletes all ports that have the other_config:transient value set
              to  true.  This  is important on certain environments where some
              ports are going to be recreated after reboot,  but  other  ports
              need to be persisted in the database.

       The following options are less important:

              Specifies  the  current  working  directory that the OVS daemons
              should run from.  The default is / (the root directory) if  this
              option  is  not  specified.  (This option is useful because most
              systems create core files in a process's current working  direc‐
              tory  and  because  a  file system that is in use as a process's
              current working directory cannot be unmounted.)

              By default, ovs-ctl enables core  dumps  for  the  OVS  daemons.
              This option disables that behavior.

              By default ovs-ctl passes --mlockall to ovs-vswitchd, requesting
              that it lock all of its virtual memory, preventing it from being
              paged to disk.  This option suppresses that behavior.

              Sets  the  nice(1)  level  used  for  each  daemon.  All of them
              default to -10.

              Configures the specified daemon to run under wrapper,  which  is
              one of the following:

                     Run  the  daemon  under  valgrind(1), if it is installed,
                     logging to daemon.valgrind.log.pid in the log directory.

              strace Run the daemon under strace(1), if it is installed,  log‐
                     ging to daemon.strace.log.pid in the log directory.

              glibc  Enable  GNU  C  library  features designed to find memory

              By default, no wrapper is used.

              Each of the wrappers can expose bugs in Open vSwitch  that  lead
              to  incorrect  operation,  including  crashes.  The valgrind and
              strace wrappers greatly slow daemon operations  so  they  should
              not  be  used  in production.  They also produce voluminous logs
              that can quickly fill small disk partitions.  The glibc  wrapper
              is less resource-intensive but still somewhat slows the daemons.

       The following options control file locations.  They should only be used
       if the default locations cannot be used.  See FILES,  below,  for  more

              Overrides the file name for the OVS database.

              Overrides  the file name for the Unix domain socket used to con‐
              nect to ovsdb-server.

              Overrides the file name for the OVS database schema.

              Adds file as an extra database for ovsdb-server  to  serve  out.
              Multiple space-separated file names may also be specified.  file
              should begin with /; if it does not, then it will  be  taken  as
              relative to dbdir.

The ``stop'' command
       The stop command does not unload the Open vSwitch kernel modules.

       This  command does nothing and finishes successfully if the OVS daemons
       aren't running.

The ``restart'' command
       The restart command performs a stop followed by a start  command.   The
       command  can  take  the  same  options as that of the start command. In
       addition, it saves and restores  OpenFlow  flows  for  each  individual

The ``status'' command
       The  status  command  checks  whether  the OVS daemons ovs-vswitchd and
       ovsdb-server are running and prints messages with that information.  It
       exits with status 0 if the daemons are running, 1 otherwise.

The ``version'' command
       The version command runs ovsdb-server --version and ovs-vswitchd --ver

The ``force-reload-kmod'' command
       The force-reload-kmod command allows upgrading the Open vSwitch  kernel
       module without rebooting.  It performs the following tasks:

       1.     Gets  a  list  of  OVS ``internal'' interfaces, that is, network
              devices implemented by Open vSwitch.  The most  common  examples
              of these are bridge ``local ports''.

       2.     Saves the OpenFlow flows of each bridge.

       3.     Stops the Open vSwitch daemons, as if by a call to ovs-ctl stop.

       4.     Saves  the kernel configuration state of the OVS internal inter‐
              faces listed in step 1, including  IP  and  IPv6  addresses  and
              routing table entries.

       5.     Unloads  the  Open  vSwitch  kernel module (including the bridge
              compatibility module if it is loaded).

       6.     Starts OVS back up, as if by a  call  to  ovs-ctl  start.   This
              reloads  the kernel module, restarts the OVS daemons and finally
              restores the saved OpenFlow flows.

       7.     Restores the kernel configuration state that was saved  in  step

       8.     Checks  for  daemons  that may need to be restarted because they
              have packet sockets that are listening on old instances of  Open
              vSwitch kernel interfaces and, if it finds any, prints a warning
              on stdout.  DHCP is a common example: if the ISC DHCP client  is
              running  on  an  OVS internal interface, then it will have to be
              restarted after completing the above procedure.   (It  would  be
              nice  if  ovs-ctl  could  restart daemons automatically, but the
              details are far too specific to a  particular  distribution  and

       force-kmod-reload internally stops and starts OVS, so it accepts all of
       the options accepted by the start command.

The ``load-kmod'' command
       The load-kmod command loads the openvswitch kernel modules if they  are
       not  already  loaded.  This  operation also occurs as part of the start
       command. The motivation for providing the load-kmod command is to allow
       errors when loading modules to be handled separatetly from other errors
       that may occur when running the start command.

       By default the load-kmod command attempts to load the openvswitch  ker‐
       nel module.

The ``enable-protocol'' command
       The  enable-protocol  command  checks  for rules related to a specified
       protocol in the system's iptables(8) configuration.  If  there  are  no
       rules  specifically related to that protocol, then it inserts a rule to
       accept the specified protocol.

       More specifically:

       ·      If iptables is not installed or not enabled, this  command  does
              nothing, assuming that lack of filtering means that the protocol
              is enabled.

       ·      If the INPUT chain has a rule that matches the specified  proto‐
              col, then this command does nothing, assuming that whatever rule
              is installed reflects the system administrator's decisions.

       ·      Otherwise, this command installs a rule that accepts traffic  of
              the specified protocol.

       This  command normally completes successfully, even if it does nothing.
       Only the failure of an attempt to insert a rule normally causes  it  to
       return  an  exit  code other than 0.  The following options control the
       protocol to be enabled:

              The name of the IP protocol to be enabled, such as gre  or  tcp.
              The default is gre.

              TCP  or  UDP  source  or  destination  port to match.  These are
              optional and allowed only with --protocol=tcp or --protocol=udp.

The ``help'' command
       Prints a usage message and exits successfully.

       In addition to the options listed for each command above,  this  option
       controls the behavior of several of ovs-ctl's commands.

       ovs-ctl  exits  with  status  0 on success and nonzero on failure.  The
       start command is considered to succeed if OVS is already  started;  the
       stop command is considered to succeed if OVS is already stopped.

       The following environment variables affect ovs-ctl:

       PATH   ovs-ctl  does  not  hardcode the location of any of the programs
              that it runs.  ovs-ctl will add the sbindir and bindir that were
              specified  at  configure  time  to PATH, if they are not already

              Setting one of these variables in the environment overrides  the
              respective configure option, both for ovs-ctl itself and for the
              other Open vSwitch programs that it runs.

       ovs-ctl uses the following files:

              Shell function library used internally by ovs-ctl.  It  must  be
              installed in the same directory as ovs-ctl.

              Per-daemon logfiles.

              Per-daemon  pidfiles  to  track  whether a daemon is running and
              with what process ID.

              The OVS database schema used to  initialize  the  database  (use
              --db-schema to override this location).

              The OVS database (use --db-file to override this location).

              The  Unix  domain  socket  used  for  local  communication  with
              ovsdb-server (use --db-sock to override this location).

              The persistent system UUID created and read by  --system-id=ran

              The  system-type   and system-version values stored in the data‐
              base's Open_vSwitch table when not specified as  a  command-line

       The files debian/openvswitch-switch.init and xenserver/etc_init.d_open
       vswitch in the Open vSwitch source distribution are  good  examples  of
       how to use ovs-ctl.

       README.md, INSTALL.Linux.md, ovsdb-server(8), ovs-vswitchd(8).

Open vSwitch                       June 2011                        ovs-ctl(8)