NAME | SYNOPSIS | DESCRIPTION | The ``start'' command | The ``stop'' command | The ``restart'' command | The ``status'' command | The ``version'' command | The ``force-reload-kmod'' command | The ``load-kmod'' command | The ``enable-protocol'' command | The ``delete-transient-ports'' command | The ``help'' command | OPTIONS | EXIT STATUS | ENVIRONMENT | FILES | EXAMPLE | SEE ALSO | COLOPHON

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

NAME         top

       ovs-ctl - OVS startup helper script

SYNOPSIS         top

       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 delete-transient-ports
       ovs-ctl help | -h | --help
       ovs-ctl --version

DESCRIPTION         top

       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         top

       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
              kernel module again.  (This is because the Open vSwitch kernel
              module cannot coexist with the Linux bridge module before

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

       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
              external-ids:system-id in the database's Open_vSwitch table.
              Remote managers that talk to the Open vSwitch database server
              over network 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

              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

              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
              system-type.conf and system-version.conf files(see section
              FILES) or it uses the lsb_release program, if present, to
              provide reasonable 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
              environments 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 environments.  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
              directory 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

              Disable self-confinement for ovs-vswitchd and ovsdb-server
              daemons.  This flag may be used when, for example, OpenFlow
              controller 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,

              ·      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
                     running on the same host as OVS and share similar
                     attack vectors.

              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 in the log

              strace Run the daemon under strace(1), if it is installed,
                     logging to 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 information.

              Overrides the file name for the OVS database.

              Overrides the file name for the Unix domain socket used to
              connect 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         top

       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         top

       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         top

       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         top

       The version command runs ovsdb-server --version and ovs-vswitchd

The ``force-reload-kmod'' command         top

       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

       4.     Saves the kernel configuration state of the OVS internal
              interfaces 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 installation.)

       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         top

       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
       kernel module.

The ``enable-protocol'' command         top

       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
              protocol, then this command does nothing, assuming that
              whatever rule is installed reflects the system administrator's

       ·      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

The ``delete-transient-ports'' command         top

       Deletes all ports that have the other_config:transient value set to

The ``help'' command         top

       Prints a usage message and exits successfully.

OPTIONS         top

       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

EXIT STATUS         top

       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.

ENVIRONMENT         top

       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 present.

              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.

FILES         top

       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

              The system-type  and system-version values stored in the
              database's Open_vSwitch table when not specified as a command-
              line option.

EXAMPLE         top

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

SEE ALSO         top

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

COLOPHON         top

       This page is part of the Open vSwitch (a distributed virtual
       multilayer switch) project.  Information about the project can be
       found at ⟨⟩.  If you have a bug report for
       this manual page, send it to  This page was
       obtained from the project's upstream Git repository
       ⟨⟩ on 2019-11-19.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2019-11-19.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to

Open vSwitch                      June 2011                       ovs-ctl(8)

Pages that refer to this page: ovs-kmod-ctl(8)ovs-vswitchd(8)