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]  en
       ovs-ctl delete-transient-ports
       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 ad‐
       ministrators 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, unless the --no-ovsdb-server command option
              is given.

       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
       running, or if the --no-ovs-vswitchd command option is given:

       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 an‐
              other 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 hu‐
              man 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.

              Ordinarily Open vSwitch daemons are started as the user invoking
              the ovs-ctl command.  Some system administrators would prefer to
              have the various daemons spawn as different users in their envi‐
              ronments.   This  option allows passing the --user option to the
              ovsdb-server and ovs-vswitchd daemons, allowing them  to  change
              their privilege levels.

       The following options are less important:

              By   default   ovs-ctl  passes  --monitor  to  ovs-vswitchd  and
              ovsdb-server, requesting that it spawn a process  monitor  which
              will  restart  the daemon if it crashes.  This option suppresses
              that behavior.

              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.

              Disable self-confinement for ovs-vswitchd and ovsdb-server  dae‐
              mons.   This  flag  may be used when, for example, OpenFlow con‐
              troller creates its Unix Domain Socket outside OVS run directory
              and  OVS needs to connect to it.  It is better to stick with the
              default behavior and not to use this flag, unless:

              •      You have Open vSwitch running under SELinux  or  AppArmor
                     Mandatory  Access  Control  that  would  prevent OVS from
                     messing with sockets outside ordinary OVS directories.

              •      You believe that relying  on  protocol  handshakes  (e.g.
                     OpenFlow)  is enough to prevent OVS to adversely interact
                     with other daemons running on your system.

              •      You don't have much worries of remote OVSDB  exploits  in
                     the  first place, because, perhaps, OVSDB manager is run‐
                     ning on the same host as OVS  and  share  similar  attack

              Sets  the  nice(1)  level used for each daemon.  All of them de‐
              fault 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 er‐

              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. It
       can take the same --no-ovsdb-server and  --no-ovs-vswitchd  options  as
       that of the start command.

       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 ad‐
       dition, 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 de‐
              vices 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 de‐
              tails are far too specific to a particular distribution and  in‐

       force-kmod-reload internally stops and starts OVS, so it accepts all of
       the  options  accepted  by   the   start   command   except   for   the
       --no-ovs-vswitchd option.

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  op‐
              tional and allowed only with --protocol=tcp or --protocol=udp.

The ``delete-transient-ports'' command
       Deletes  all  ports  that  have the other_config:transient value set to

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

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

       By default, ovs-ctl will control the ovsdb-server, and the ovs-vswitchd
       daemons. The following options restrict that control to exclude one  or
       the other:

              Specifies  that  the  ovs-ctl  commands start, stop, and restart
              should not modify the running status of ovsdb-server.

              Specifies that the ovs-ctl commands  start,  stop,  and  restart
              should  not modify the running status of ovs-vswitchd.  It is an
              error to include this option with the force-reload-kmod command.

       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.rst, ovsdb-server(8), ovs-vswitchd(8).

Open vSwitch                       June 2011                        ovs-ctl(8)