DOKK / manpages / debian 10 / openvswitch-common / ovs-ofctl.8.en
ovs-ofctl(8) Open vSwitch Manual ovs-ofctl(8)

ovs-ofctl - administer OpenFlow switches

ovs-ofctl [options] command [switch] [args...]

The ovs-ofctl program is a command line tool for monitoring and administering OpenFlow switches. It can also show the current state of an OpenFlow switch, including features, configuration, and table entries. It should work with any OpenFlow switch, not just Open vSwitch.

These commands allow ovs-ofctl to monitor and administer an OpenFlow switch. It is able to show the current state of a switch, including features, configuration, and table entries.

Most of these commands take an argument that specifies the method for connecting to an OpenFlow switch. The following connection methods are supported:


The specified port on the given host, which can be expressed either as a DNS name (if built with unbound library) or an IP address in IPv4 or IPv6 address format. Wrap IPv6 addresses in square brackets, e.g. tcp:[::1]:6653. On Linux, use %device to designate a scope for IPv6 link-level addresses, e.g. tcp:[fe80::1234%eth0]:6653. For ssl, the --private-key, --certificate, and --ca-cert options are mandatory.
If port is not specified, it defaults to 6653.
On POSIX, a Unix domain server socket named file.
On Windows, connect to a local named pipe that is represented by a file created in the path file to mimic the behavior of a Unix domain socket.
This is short for unix:file, as long as file does not contain a colon.
This is short for unix:/var/run/openvswitch/bridge.mgmt, as long as bridge does not contain a colon.
[type@]dp
Attempts to look up the bridge associated with dp and open as above. If type is given, it specifies the datapath provider of dp, otherwise the default provider system is assumed.
Prints to the console information on switch, including information on its flow tables and ports.
Prints to the console statistics for each of the flow tables used by switch.
Prints to the console features for each of the flow tables used by switch.
Prints to the console configuration for each of the flow tables used by switch for OpenFlow 1.4+.
This command configures flow table settings in switch for OpenFlow table table, which may be expressed as a number or (unless --no-names is specified) a name.
The available settings depend on the OpenFlow version in use. In OpenFlow 1.1 and 1.2 (which must be enabled with the -O option) only, mod-table configures behavior when no flow is found when a packet is looked up in a flow table. The following setting values are available:
Drop the packet.
Continue to the next table in the pipeline. (This is how an OpenFlow 1.0 switch always handles packets that do not match any flow, in tables other than the last one.)
Send to controller. (This is how an OpenFlow 1.0 switch always handles packets that do not match any flow in the last table.)
In OpenFlow 1.4 and later (which must be enabled with the -O option) only, mod-table configures the behavior when a controller attempts to add a flow to a flow table that is full. The following setting values are available:
Delete some existing flow from the flow table, according to the algorithm described for the Flow_Table table in ovs-vswitchd.conf.db(5).
Refuse to add the new flow. (Eviction might still be enabled through the overflow_policy column in the Flow_Table table documented in ovs-vswitchd.conf.db(5).)
Enables sending vacancy events to controllers using TABLE_STATUS messages, based on percentage thresholds low and high.
Disables vacancy events.
Prints to the console statistics for network devices associated with switch. If netdev is specified, only the statistics associated with that device will be printed. netdev can be an OpenFlow assigned port number or device name, e.g. eth0.
Prints to the console detailed information about network devices associated with switch. To dump only a specific port, specify its number as port. Otherwise, if port is omitted, or if it is specified as ANY, then all ports are printed. This is a subset of the information provided by the show command.
If the connection to switch negotiates OpenFlow 1.0, 1.2, or 1.2, this command uses an OpenFlow extension only implemented in Open vSwitch (version 1.7 and later).
Only OpenFlow 1.5 and later support dumping a specific port. Earlier versions of OpenFlow always dump all ports.
Modify characteristics of port port in switch. port may be an OpenFlow port number or name (unless --no-names is specified) or the keyword LOCAL (the preferred way to refer to the OpenFlow local port). The action may be any one of the following:


Enable or disable the interface. This is equivalent to ip link set up or ip link set down on a Unix system.

Enable or disable 802.1D spanning tree protocol (STP) on the interface. OpenFlow implementations that don't support STP will refuse to enable it.



Enable or disable OpenFlow processing of packets received on this interface. When packet processing is disabled, packets will be dropped instead of being processed through the OpenFlow table. The receive or no-receive setting applies to all packets except 802.1D spanning tree packets, which are separately controlled by receive-stp or no-receive-stp.

Allow or disallow forwarding of traffic to this interface. By default, forwarding is enabled.

Controls whether an OpenFlow flood action will send traffic out this interface. By default, flooding is enabled. Disabling flooding is primarily useful to prevent loops when a spanning tree protocol is not in use.

Controls whether packets received on this interface that do not match a flow table entry generate a ``packet in'' message to the OpenFlow controller. By default, ``packet in'' messages are enabled.
The show command displays (among other information) the configuration that mod-port changes.
Prints switch's fragment handling mode. See set-frags, below, for a description of each fragment handling mode.
The show command also prints the fragment handling mode among its other output.
Configures switch's treatment of IPv4 and IPv6 fragments. The choices for frag_mode are:
Fragments pass through the flow table like non-fragmented packets. The TCP ports, UDP ports, and ICMP type and code fields are always set to 0, even for fragments where that information would otherwise be available (fragments with offset 0). This is the default fragment handling mode for an OpenFlow switch.
Fragments are dropped without passing through the flow table.
The switch reassembles fragments into full IP packets before passing them through the flow table. Open vSwitch does not implement this fragment handling mode.
Fragments pass through the flow table like non-fragmented packets. The TCP ports, UDP ports, and ICMP type and code fields are available for matching for fragments with offset 0, and set to 0 in fragments with nonzero offset. This mode is a Nicira extension.
See the description of ip_frag, below, for a way to match on whether a packet is a fragment and on its fragment offset.
Prints to the console all flow entries in switch's tables that match flows. If flows is omitted, all flows in the switch are retrieved. See Flow Syntax, below, for the syntax of flows. The output format is described in Table Entry Output.
By default, ovs-ofctl prints flow entries in the same order that the switch sends them, which is unlikely to be intuitive or consistent. Use --sort and --rsort to control display order. The --names/--no-names and --stats/--no-stats options also affect output formatting. See the descriptions of these options, under OPTIONS below, for more information
Prints to the console aggregate statistics for flows in switch's tables that match flows. If flows is omitted, the statistics are aggregated across all flows in the switch's flow tables. See Flow Syntax, below, for the syntax of flows. The output format is described in Table Entry Output.
Prints to the console statistics for the specified queue on port within switch. port can be an OpenFlow port number or name, the keyword LOCAL (the preferred way to refer to the OpenFlow local port), or the keyword ALL. Either of port or queue or both may be omitted (or equivalently the keyword ALL). If both are omitted, statistics are printed for all queues on all ports. If only queue is omitted, then statistics are printed for all queues on port; if only port is omitted, then statistics are printed for queue on every port where it exists.
Prints to the console the configuration of queue on port in switch. If port is omitted or ANY, reports queues for all port. If queue is omitted or ANY, reports all queues. For OpenFlow 1.3 and earlier, the output always includes all queues, ignoring queue if specified.
This command has limited usefulness, because ports often have no configured queues and because the OpenFlow protocol provides only very limited information about the configuration of a queue.
Prints to the console the statistics of bridge IPFIX for switch. If bridge IPFIX is configured on the switch, IPFIX statistics can be retrieved. Otherwise, error message will be printed.
This command uses an Open vSwitch extension that is only in Open vSwitch 2.6 and later.
Prints to the console the statistics of flow-based IPFIX for switch. If flow-based IPFIX is configured on the switch, statistics of all the collector set ids on the switch will be printed. Otherwise, print error message.
Refer to ovs-vswitchd.conf.db(5) for more details on configuring flow based IPFIX and collector set ids.
This command uses an Open vSwitch extension that is only in Open vSwitch 2.6 and later.
Flushes the connection tracking entries in zone on switch.
This command uses an Open vSwitch extension that is only in Open vSwitch 2.6 and later.

These commands manage the flow table in an OpenFlow switch. In each case, flow specifies a flow entry in the format described in Flow Syntax, below, file is a text file that contains zero or more flows in the same syntax, one per line, and the optional --bundle option operates the command as a single atomic transation, see option --bundle, below.

[--bundle] add-flow switch flow

[--bundle] add-flow switch - < file

[--bundle] add-flows switch file
Add each flow entry to switch's tables. Each flow specification (e.g., each line in file) may start with add, modify, delete, modify_strict, or delete_strict keyword to specify whether a flow is to be added, modified, or deleted, and whether the modify or delete is strict or not. For backwards compatibility a flow specification without one of these keywords is treated as a flow add. All flow mods are executed in the order specified.
[--bundle] [--strict] mod-flows switch flow

[--bundle] [--strict] mod-flows switch - < file
Modify the actions in entries from switch's tables that match the specified flows. With --strict, wildcards are not treated as active for matching purposes.
[--bundle] del-flows switch

[--bundle] [--strict] del-flows switch [flow]

[--bundle] [--strict] del-flows switch - < file
Deletes entries from switch's flow table. With only a switch argument, deletes all flows. Otherwise, deletes flow entries that match the specified flows. With --strict, wildcards are not treated as active for matching purposes.
[--bundle] [--readd] replace-flows switch file
Reads flow entries from file (or stdin if file is -) and queries the flow table from switch. Then it fixes up any differences, adding flows from flow that are missing on switch, deleting flows from switch that are not in file, and updating flows in switch whose actions, cookie, or timeouts differ in file.
With --readd, ovs-ofctl adds all the flows from file, even those that exist with the same actions, cookie, and timeout in switch. In OpenFlow 1.0 and 1.1, re-adding a flow always resets the flow's packet and byte counters to 0, and in OpenFlow 1.2 and later, it does so only if the reset_counts flag is set.
Reads flow entries from source1 and source2 and prints the differences. A flow that is in source1 but not in source2 is printed preceded by a -, and a flow that is in source2 but not in source1 is printed preceded by a +. If a flow exists in both source1 and source2 with different actions, cookie, or timeouts, then both versions are printed preceded by - and +, respectively.
source1 and source2 may each name a file or a switch. If a name begins with / or ., then it is considered to be a file name. A name that contains : is considered to be a switch. Otherwise, it is a file if a file by that name exists, a switch if not.
For this command, an exit status of 0 means that no differences were found, 1 means that an error occurred, and 2 means that some differences were found.
Connects to switch and instructs it to execute the packet-out OpenFlow message, specified as defined in Packet-Out Syntax section.

These commands manage the group table in an OpenFlow switch. In each case, group specifies a group entry in the format described in Group Syntax, below, and file is a text file that contains zero or more groups in the same syntax, one per line, and the optional --bundle option operates the command as a single atomic transation, see option --bundle, below.

The group commands work only with switches that support OpenFlow 1.1 or later or the Open vSwitch group extensions to OpenFlow 1.0 (added in Open vSwitch 2.9.90). For OpenFlow 1.1 or later, it is necessary to explicitly enable these protocol versions in ovs-ofctl (using -O). For more information, see ``Q: What versions of OpenFlow does Open vSwitch support?'' in the Open vSwitch FAQ.

[--bundle] add-group switch group

[--bundle] add-group switch - < file

[--bundle] add-groups switch file
Add each group entry to switch's tables. Each group specification (e.g., each line in file) may start with add, modify, add_or_mod, delete, insert_bucket, or remove_bucket keyword to specify whether a flow is to be added, modified, or deleted, or whether a group bucket is to be added or removed. For backwards compatibility a group specification without one of these keywords is treated as a group add. All group mods are executed in the order specified.
[--bundle] [--may-create] mod-group switch group

[--bundle] [--may-create] mod-group switch - < file
Modify the action buckets in entries from switch's tables for each group entry. If a specified group does not already exist, then without --may-create, this command has no effect; with --may-create, it creates a new group. The --may-create option uses an Open vSwitch extension to OpenFlow only implemented in Open vSwitch 2.6 and later.
[--bundle] del-groups switch

[--bundle] del-groups switch [group]

[--bundle] del-groups switch - < file
Deletes entries from switch's group table. With only a switch argument, deletes all groups. Otherwise, deletes the group for each group entry.
[--bundle] insert-buckets switch group

[--bundle] insert-buckets switch - < file
Add buckets to an existing group present in the switch's group table. If no command_bucket_id is present in the group specification then all buckets of the group are removed.
[--bundle] remove-buckets switch group

[--bundle] remove-buckets switch - < file
Remove buckets to an existing group present in the switch's group table. If no command_bucket_id is present in the group specification then all buckets of the group are removed.
Prints group entries in switch's tables to console. To dump only a specific group, specify its number as group. Otherwise, if group is omitted, or if it is specified as ALL, then all groups are printed.
Only OpenFlow 1.5 and later support dumping a specific group. Earlier versions of OpenFlow always dump all groups.
Prints to the console the group features of the switch.
Prints to the console statistics for the specified group in switch's tables. If group is omitted then statistics for all groups are printed.

These commands manage the meter table in an OpenFlow switch. In each case, meter specifies a meter entry in the format described in Meter Syntax, below.

OpenFlow 1.3 introduced support for meters, so these commands only work with switches that support OpenFlow 1.3 or later. It is necessary to explicitly enable these protocol versions in ovs-ofctl (using -O) and in the switch itself (with the protocols column in the Bridge table). For more information, see ``Q: What versions of OpenFlow does Open vSwitch support?'' in the Open vSwitch FAQ.

Add a meter entry to switch's tables. The meter syntax is described in section Meter Syntax, below.
Modify an existing meter.
Delete entries from switch's meter table. To delete only a specific meter, specify its number as meter. Otherwise, if meter is omitted, or if it is specified as all, then all meters are deleted.
Print entries from switch's meter table. To print only a specific meter, specify its number as meter. Otherwise, if meter is omitted, or if it is specified as all, then all meters are printed.
Print meter statistics. meter can specify a single meter with syntax meter=id, or all meters with syntax meter=all.
Print meter features.

Transactional updates to both flow and group tables can be made with the bundle command. file is a text file that contains zero or more flow mods, group mods, or packet-outs in Flow Syntax, Group Syntax, or Packet-Out Syntax, each line preceded by flow, group, or packet-out keyword, correspondingly. The flow keyword may be optionally followed by one of the keywords add, modify, modify_strict, delete, or delete_strict, of which the add is assumed if a bare flow is given. Similarly, the group keyword may be optionally followed by one of the keywords add, modify, add_or_mod, delete, insert_bucket, or remove_bucket, of which the add is assumed if a bare group is given.

Execute all flow and group mods in file as a single atomic transaction against switch's tables. All bundled mods are executed in the order specified.

Open vSwitch maintains a mapping table between tunnel option TLVs (defined by <class, type, length>) and NXM fields tun_metadatan, where n ranges from 0 to 63, that can be operated on for the purposes of matches, actions, etc. This TLV table can be used for Geneve option TLVs or other protocols with options in same TLV format as Geneve options. This mapping must be explicitly specified by the user through the following commands.

A TLV mapping is specified with the syntax {class=class,type=type,len=length}->tun_metadatan. When an option mapping exists for a given tun_metadatan, matching on the defined field becomes possible, e.g.:

ovs-ofctl add-tlv-map br0 "{class=0xffff,type=0,len=4}->tun_metadata0"

ovs-ofctl add-flow br0 tun_metadata0=1234,actions=controller

A mapping should not be changed while it is in active use by a flow. The result of doing so is undefined.

These commands are Nicira extensions to OpenFlow and require Open vSwitch 2.5 or later.

Add each option to switch's tables. Duplicate fields are rejected.
Delete each option from switch's table, or all option TLV mapping if no option is specified. Fields that aren't mapped are ignored.
Show the currently mapped fields in the switch's option table as well as switch capabilities.

Connects to switch and prints to the console all OpenFlow messages received. Unlike other ovs-ofctl commands, if switch is the name of a bridge, then the snoop command connects to a Unix domain socket named /var/run/openvswitch/switch.snoop. ovs-vswitchd listens on such a socket for each bridge and sends to it all of the OpenFlow messages sent to or received from its configured OpenFlow controller. Thus, this command can be used to view OpenFlow protocol activity between a switch and its controller.
When a switch has more than one controller configured, only the traffic to and from a single controller is output. If none of the controllers is configured as a master or a slave (using a Nicira extension to OpenFlow 1.0 or 1.1, or a standard request in OpenFlow 1.2 or later), then a controller is chosen arbitrarily among them. If there is a master controller, it is chosen; otherwise, if there are any controllers that are not masters or slaves, one is chosen arbitrarily; otherwise, a slave controller is chosen arbitrarily. This choice is made once at connection time and does not change as controllers reconfigure their roles.
If a switch has no controller configured, or if the configured controller is disconnected, no traffic is sent, so monitoring will not show any traffic.
Connects to switch and prints to the console all OpenFlow messages received. Usually, switch should specify the name of a bridge in the ovs-vswitchd database.
If miss-len is provided, ovs-ofctl sends an OpenFlow ``set configuration'' message at connection setup time that requests miss-len bytes of each packet that misses the flow table. Open vSwitch does not send these and other asynchronous messages to an ovs-ofctl monitor client connection unless a nonzero value is specified on this argument. (Thus, if miss-len is not specified, very little traffic will ordinarily be printed.)
If invalid_ttl is passed, ovs-ofctl sends an OpenFlow ``set configuration'' message at connection setup time that requests INVALID_TTL_TO_CONTROLLER, so that ovs-ofctl monitor can receive ``packet-in'' messages when TTL reaches zero on dec_ttl action. Only OpenFlow 1.1 and 1.2 support invalid_ttl; Open vSwitch also implements it for OpenFlow 1.0 as an extension.
watch:[spec...] causes ovs-ofctl to send a ``monitor request'' Nicira extension message to the switch at connection setup time. This message causes the switch to send information about flow table changes as they occur. The following comma-separated spec syntax is available:
!initial
Do not report the switch's initial flow table contents.
!add
Do not report newly added flows.
!delete
Do not report deleted flows.
!modify
Do not report modifications to existing flows.
!own
Abbreviate changes made to the flow table by ovs-ofctl's own connection to the switch. (These could only occur using the ofctl/send command described below under RUNTIME MANAGEMENT COMMANDS.)
!actions
Do not report actions as part of flow updates.
Limits the monitoring to the table with the given table, which may be expressed as a number between 0 and 254 or (unless --no-names is specified) a name. By default, all tables are monitored.
If set, only flows that output to port are monitored. The port may be an OpenFlow port number or keyword (e.g. LOCAL).
Monitors only flows that have field specified as the given value. Any syntax valid for matching on dump-flows may be used.
This command may be useful for debugging switch or controller implementations. With watch:, it is particularly useful for observing how a controller updates flow tables.

The following commands, like those in the previous section, may be applied to OpenFlow switches, using any of the connection methods described in that section. Unlike those commands, these may also be applied to OpenFlow controllers.

Sends a single OpenFlow echo-request message to target and waits for the response. With the -t or --timeout option, this command can test whether an OpenFlow switch or controller is up and running.
Sends a series of 10 echo request packets to target and times each reply. The echo request packets consist of an OpenFlow header plus n bytes (default: 64) of randomly generated payload. This measures the latency of individual requests.
Sends count echo request packets that each consist of an OpenFlow header plus n bytes of payload and waits for each response. Reports the total time required. This is a measure of the maximum bandwidth to target for round-trips of n-byte messages.

Reads file (or stdin if file is -) as a series of OpenFlow messages in the binary format used on an OpenFlow connection, and prints them to the console. This can be useful for printing OpenFlow messages captured from a TCP stream.
Reads file, which must be in the PCAP format used by network capture tools such as tcpdump or wireshark, extracts all the TCP streams for OpenFlow connections, and prints the OpenFlow messages in those connections in human-readable format on stdout.
OpenFlow connections are distinguished by TCP port number. Non-OpenFlow packets are ignored. By default, data on TCP ports 6633 and 6653 are considered to be OpenFlow. Specify one or more port arguments to override the default.
This command cannot usefully print SSL encrypted traffic. It does not understand IPv6.

Some ovs-ofctl commands accept an argument that describes a flow or flows. Such flow descriptions comprise a series of field=value assignments, separated by commas or white space. (Embedding spaces into a flow description normally requires quoting to prevent the shell from breaking the description into multiple arguments.)

Flow descriptions should be in normal form. This means that a flow may only specify a value for an L3 field if it also specifies a particular L2 protocol, and that a flow may only specify an L4 field if it also specifies particular L2 and L3 protocol types. For example, if the L2 protocol type dl_type is wildcarded, then L3 fields nw_src, nw_dst, and nw_proto must also be wildcarded. Similarly, if dl_type or nw_proto (the L3 protocol type) is wildcarded, so must be the L4 fields tcp_dst and tcp_src. ovs-ofctl will warn about flows not in normal form.

ovs-fields(7) describes the supported fields and how to match them. In addition to match fields, commands that operate on flows accept a few additional key-value pairs:

For flow dump commands, limits the flows dumped to those in table, which may be expressed as a number between 0 and 255 or (unless --no-names is specified) a name. If not specified (or if 255 is specified as table), then flows in all tables are dumped.
For flow table modification commands, behavior varies based on the OpenFlow version used to connect to the switch:
OpenFlow 1.0 does not support table for modifying flows. ovs-ofctl will exit with an error if table (other than table=255) is specified for a switch that only supports OpenFlow 1.0.
In OpenFlow 1.0, the switch chooses the table into which to insert a new flow. The Open vSwitch software switch always chooses table 0. Other Open vSwitch datapaths and other OpenFlow implementations may choose different tables.
The OpenFlow 1.0 behavior in Open vSwitch for modifying or removing flows depends on whether --strict is used. Without --strict, the command applies to matching flows in all tables. With --strict, the command will operate on any single matching flow in any table; it will do nothing if there are matches in more than one table. (The distinction between these behaviors only matters if non-OpenFlow 1.0 commands were also used, because OpenFlow 1.0 alone cannot add flows with the same matching criteria to multiple tables.)
Open vSwitch implements an OpenFlow extension that allows the controller to specify the table on which to operate. ovs-ofctl automatically enables the extension when table is specified and OpenFlow 1.0 is used. ovs-ofctl automatically detects whether the switch supports the extension. As of this writing, this extension is only known to be implemented by Open vSwitch.
With this extension, ovs-ofctl operates on the requested table when table is specified, and acts as described for OpenFlow 1.0 above when no table is specified (or for table=255).
OpenFlow 1.1 requires flow table modification commands to specify a table. When table is not specified (or table=255 is specified), ovs-ofctl defaults to table 0.
OpenFlow 1.2 and later allow flow deletion commands, but not other flow table modification commands, to operate on all flow tables, with the behavior described above for OpenFlow 1.0.


ovs-ofctl ignores assignments to these ``fields'' to allow output from the dump-flows command to be used as input for other commands that parse flows.

The add-flow, add-flows, and mod-flows commands require an additional field, which must be the final field specified:

Specifies a comma-separated list of actions to take on a packet when the flow entry matches. If no action is specified, then packets matching the flow are dropped. The following forms of action are supported:

Outputs the packet to OpenFlow port number port. If port is the packet's input port, the packet is not output.
Outputs the packet to the OpenFlow port number read from src, which may be an NXM field name, as described above, or a match field name. output:reg0[16..31] outputs to the OpenFlow port number written in the upper half of register 0. If the port number is the packet's input port, the packet is not output.
This form of output was added in Open vSwitch 1.3.0. This form of output uses an OpenFlow extension that is not supported by standard OpenFlow switches.
Outputs the packet to the OpenFlow port number read from port, with maximum packet size set to nbytes. port may be OpenFlow port number, local, or in_port. Patch port is not supported. Packets larger than nbytes will be trimmed to nbytes while packets smaller than nbytes remains the original size.
Outputs the packet to the OpenFlow group group_id. OpenFlow 1.1 introduced support for groups; Open vSwitch 2.6 and later also supports output to groups as an extension to OpenFlow 1.0. See Group Syntax for more details.
Subjects the packet to the device's normal L2/L3 processing. (This action is not implemented by all OpenFlow switches.)
Outputs the packet on all switch physical ports other than the port on which it was received and any ports on which flooding is disabled (typically, these would be ports disabled by the IEEE 802.1D spanning tree protocol).
Outputs the packet on all switch physical ports other than the port on which it was received.
Outputs the packet on the ``local port,'' which corresponds to the network device that has the same name as the bridge.
Outputs the packet on the port from which it was received.
Sends the packet and its metadata to the OpenFlow controller as a ``packet in'' message. The supported key-value pairs are:
Limit to nbytes the number of bytes of the packet to send to the controller. By default the entire packet is sent.
Specify reason as the reason for sending the message in the ``packet in'' message. The supported reasons are action (the default), no_match, and invalid_ttl.
Specify controller-id, a 16-bit integer, as the connection ID of the OpenFlow controller or controllers to which the ``packet in'' message should be sent. The default is zero. Zero is also the default connection ID for each controller connection, and a given controller connection will only have a nonzero connection ID if its controller uses the NXT_SET_CONTROLLER_ID Nicira extension to OpenFlow.
Supplies the bytes represented as hex digits hh as additional data to the controller in the packet-in message. Pairs of hex digits may be separated by periods for readability.
Causes the switch to freeze the packet's trip through Open vSwitch flow tables and serializes that state into the packet-in message as a ``continuation,'' an additional property in the NXT_PACKET_IN2 message. The controller can later send the continuation back to the switch in an NXT_RESUME message, which will restart the packet's traversal from the point where it was interrupted. This permits an OpenFlow controller to interpose on a packet midway through processing in Open vSwitch.
Use meter id to rate-limit the OpenFlow packet-in messages that this action sends to the controller. By default, packets sent to the controller are associated with the "controller" virtual meter, if one was configured.
If any reason other than action or any nonzero controller-id is supplied, Open vSwitch extension NXAST_CONTROLLER, supported by Open vSwitch 1.6 and later, is used. If userdata is supplied, then NXAST_CONTROLLER2, supported by Open vSwitch 2.6 and later, is used.

Shorthand for controller() or controller(max_len=nbytes), respectively.
Enqueues the packet on the specified queue within port port, which must be an OpenFlow port number or keyword (e.g. LOCAL). The number of supported queues depends on the switch; some OpenFlow implementations do not support queuing at all.
Discards the packet, so no further processing or forwarding takes place. If a drop action is used, no other actions may be specified.
Modifies the VLAN id on a packet. The VLAN tag is added or modified as necessary to match the value specified. If the VLAN tag is added, a priority of zero is used (see the mod_vlan_pcp action to set this).
Modifies the VLAN priority on a packet. The VLAN tag is added or modified as necessary to match the value specified. Valid values are between 0 (lowest) and 7 (highest). If the VLAN tag is added, a vid of zero is used (see the mod_vlan_vid action to set this).
Strips the VLAN tag from a packet if it is present.
Push a new VLAN tag onto the packet. Ethertype is used as the Ethertype for the tag. Only ethertype 0x8100 should be used. (0x88a8 which the spec allows isn't supported at the moment.) A priority of zero and the tag of zero are used for the new tag.
Changes the packet's Ethertype to ethertype, which must be either 0x8847 or 0x8848, and pushes an MPLS LSE.
If the packet does not already contain any MPLS labels then an initial label stack entry is pushed. The label stack entry's label is 2 if the packet contains IPv6 and 0 otherwise, its default traffic control value is the low 3 bits of the packet's DSCP value (0 if the packet is not IP), and its TTL is copied from the IP TTL (64 if the packet is not IP).
If the packet does already contain an MPLS label, pushes a new outermost label as a copy of the existing outermost label.
A limitation of the implementation is that processing of actions will stop if push_mpls follows another push_mpls unless there is a pop_mpls in between.
Strips the outermost MPLS label stack entry. Currently the implementation restricts ethertype to a non-MPLS Ethertype and thus pop_mpls should only be applied to packets with an MPLS label stack depth of one. A further limitation is that processing of actions will stop if pop_mpls follows another pop_mpls unless there is a push_mpls in between.
Sets the source Ethernet address to mac.
Sets the destination Ethernet address to mac.
Sets the IPv4 source address to ip.
Sets the IPv4 destination address to ip.
Sets the TCP or UDP or SCTP source port to port.
Sets the TCP or UDP or SCTP destination port to port.
Sets the DSCP bits in the IPv4 ToS/DSCP or IPv6 traffic class field to tos, which must be a multiple of 4 between 0 and 255. This action does not modify the two least significant bits of the ToS field (the ECN bits).
Sets the ECN bits in the IPv4 ToS or IPv6 traffic class field to ecn, which must be a value between 0 and 3, inclusive. This action does not modify the six most significant bits of the field (the DSCP bits).
Requires OpenFlow 1.1 or later.
Sets the IPv4 TTL or IPv6 hop limit field to ttl, which is specified as a decimal number between 0 and 255, inclusive. Switch behavior when setting ttl to zero is not well specified, though.
Requires OpenFlow 1.1 or later.
The following actions are Nicira vendor extensions that, as of this writing, are only known to be implemented by Open vSwitch:


Re-searches this OpenFlow flow table (or table table, if specified) with the in_port field replaced by port (if port is specified) and the packet 5-tuple fields swapped with the corresponding conntrack original direction tuple fields (if ct is specified, see ct_nw_src above), and executes the actions found, if any, in addition to any other actions in this flow entry. The in_port and swapped 5-tuple fields are restored immediately after the search, before any actions are executed.
The table may be expressed as a number between 0 and 254 or (unless --no-names is specified) a name.
The ct option requires a valid connection tracking state as a match prerequisite in the flow where this action is placed. Examples of valid connection tracking state matches include ct_state=+new, ct_state=+est, ct_state=+rel, and ct_state=+trk-inv.
Recursive resubmit actions are obeyed up to implementation-defined limits:
  • Open vSwitch 1.0.1 and earlier did not support recursion.
  • Open vSwitch 1.0.2 and 1.0.3 limited recursion to 8 levels.
  • Open vSwitch 1.1 and 1.2 limited recursion to 16 levels.
  • Open vSwitch 1.2 through 1.8 limited recursion to 32 levels.
  • Open vSwitch 1.9 through 2.0 limited recursion to 64 levels.
  • Open vSwitch 2.1 through 2.5 limited recursion to 64 levels and impose a total limit of 4,096 resubmits per flow translation (earlier versions did not impose any total limit).
  • Open vSwitch 2.6 and later imposes the same limits as 2.5, with one exception: resubmit from table x to any table y > x does not count against the recursion limit.
Open vSwitch before 1.2.90 did not support table. Open vSwitch before 2.7 did not support ct.

If outputting to a port that encapsulates the packet in a tunnel and supports an identifier (such as GRE), sets the identifier to id. If the set_tunnel form is used and id fits in 32 bits, then this uses an action extension that is supported by Open vSwitch 1.0 and later. Otherwise, if id is a 64-bit value, it requires Open vSwitch 1.1 or later.
Sets the queue that should be used to queue when packets are output. The number of supported queues depends on the switch; some OpenFlow implementations do not support queuing at all.
Restores the queue to the value it was before any set_queue actions were applied.

Send the packet through the connection tracker. Refer to the ct_state documentation above for possible packet and connection states. A ct action always sets the packet to an untracked state and clears out the ct_state fields for the current processing path. Those fields are only available for the processing path pointed to by the table argument. The following arguments are supported:
Commit the connection to the connection tracking module. Information about the connection will be stored beyond the lifetime of the packet in the pipeline. Some ct_state flags are only available for committed connections.
A committed connection always has the directionality of the packet that caused the connection to be committed in the first place. This is the ``original direction'' of the connection, and the opposite direction is the ``reply direction''. If a connection is already committed, but it is in the wrong direction, force flag may be used in addition to commit flag to effectively terminate the existing connection and start a new one in the current direction. This flag has no effect if the original direction of the connection is already the same as that of the current packet.
Fork pipeline processing in two. The original instance of the packet will continue processing the current actions list as an untracked packet. An additional instance of the packet will be sent to the connection tracker, which will be re-injected into the OpenFlow pipeline to resume processing in table number (which may be specified as a number between 0 and 254 or, unless --no-names is specified, a name), with the ct_state and other ct match fields set. If table is not specified, then the packet which is submitted to the connection tracker is not re-injected into the OpenFlow pipeline. It is strongly recommended to specify a table later than the current table to prevent loops.

A 16-bit context id that can be used to isolate connections into separate domains, allowing overlapping network addresses in different zones. If a zone is not provided, then the default is to use zone zero. The zone may be specified either as an immediate 16-bit value, or may be provided from an NXM field src. The start and end pair are inclusive, and must specify a 16-bit range within the field. This value is copied to the ct_zone match field for packets which are re-injected into the pipeline using the table option.
Perform actions within the context of connection tracking. This is a restricted set of actions which are in the same format as their specifications as part of a flow. Only actions which modify the ct_mark or ct_label fields are accepted within the exec action, and these fields may only be modified with this option. For example:
Store a 32-bit metadata value with the connection. Subsequent lookups for packets in this connection will populate the ct_mark flow field when the packet is sent to the connection tracker with the table specified.
Store a 128-bit metadata value with the connection. Subsequent lookups for packets in this connection will populate the ct_label flow field when the packet is sent to the connection tracker with the table specified.
The commit parameter must be specified to use exec(...).
Specify application layer gateway alg to track specific connection types. If subsequent related connections are sent through the ct action, then the rel flag in the ct_state field will be set. Supported types include:
Look for negotiation of FTP data connections. Specify this option for FTP control connections to detect related data connections and populate the rel flag for the data connections.
Look for negotiation of TFTP data connections. Specify this option for TFTP control connections to detect related data connections and populate the rel flag for the data connections.
The commit parameter must be specified to use alg=alg.
When committing related connections, the ct_mark for that connection is inherited from the current ct_mark stored with the original connection (ie, the connection created by ct(alg=...)).
Note that with the Linux datapath, global sysctl options affect the usage of the ct action. In particular, if net.netfilter.nf_conntrack_helper is enabled then application layer gateway helpers may be executed even if the alg option is not specified. This is the default setting until Linux 4.7. For security reasons, the netfilter team recommends users to disable this option. See this blog post for further details: http://www.netfilter.org/news.html#2012-04-03
Specify address and port translation for the connection being tracked. For new connections either src or dst argument must be provided to set up either source address/port translation (SNAT) or destination address/port translation (DNAT), respectively. Setting up address translation for a new connection takes effect only if the commit flag is also provided for the enclosing ct action. A bare nat action will only translate the packet being processed in the way the connection has been set up with an earlier ct action. Also a nat action with src or dst, when applied to a packet belonging to an established (rather than new) connection, will behave the same as a bare nat.
src and dst options take the following arguments:
The address range from which the translated address should be selected. If only one address is given, then that address will always be selected, otherwise the address selection can be informed by the optional persistent flag as described below. Either IPv4 or IPv6 addresses can be provided, but both addresses must be of the same type, and the datapath behavior is undefined in case of providing IPv4 address range for an IPv6 packet, or IPv6 address range for an IPv4 packet. IPv6 addresses must be bracketed with '[' and ']' if a port range is also given.
The port range from which the translated port should be selected. If only one port number is provided, then that should be selected. In case of a mapping conflict the datapath may choose any other non-conflicting port number instead, even when no port range is specified. The port number selection can be informed by the optional random and hash flags as described below.
The optional flags are:
The selection of the port from the given range should be done using a fresh random number. This flag is mutually exclusive with hash.
The selection of the port from the given range should be done using a datapath specific hash of the packet's IP addresses and the other, non-mapped port number. This flag is mutually exclusive with random.
The selection of the IP address from the given range should be done so that the same mapping can be provided after the system restarts.
If an alg is specified for the committing ct action that also includes nat with a src or dst attribute, then the datapath tries to set up the helper to be NAT aware. This functionality is datapath specific and may not be supported by all datapaths.
nat was introduced in Open vSwitch 2.6. The first datapath that implements ct nat support is the one that ships with Linux 4.6.
The ct action may be used as a primitive to construct stateful firewalls by selectively committing some traffic, then matching the ct_state to allow established connections while denying new connections. The following flows provide an example of how to implement a simple firewall that allows new connections from port 1 to port 2, and only allows established connections to send traffic from port 2 to port 1:
table=0,priority=1,action=drop
table=0,priority=10,arp,action=normal
table=0,priority=100,ip,ct_state=-trk,action=ct(table=1)
table=1,in_port=1,ip,ct_state=+trk+new,action=ct(commit),2
table=1,in_port=1,ip,ct_state=+trk+est,action=2
table=1,in_port=2,ip,ct_state=+trk+new,action=drop
table=1,in_port=2,ip,ct_state=+trk+est,action=1
If ct is executed on IP (or IPv6) fragments, then the message is implicitly reassembled before sending to the connection tracker and refragmented upon output, to the original maximum received fragment size. Reassembly occurs within the context of the zone, meaning that IP fragments in different zones are not assembled together. Pipeline processing for the initial fragments is halted; When the final fragment is received, the message is assembled and pipeline processing will continue for that flow. Because packet ordering is not guaranteed by IP protocols, it is not possible to determine which IP fragment will cause message reassembly (and therefore continue pipeline processing). As such, it is strongly recommended that multiple flows should not execute ct to reassemble fragments from the same IP message.
The ct action was introduced in Open vSwitch 2.5.
Clears connection tracking state from the flow, zeroing ct_state, ct_zone, ct_mark, and ct_label.
This action was introduced in Open vSwitch 2.6.90.

Decrement TTL of IPv4 packet or hop limit of IPv6 packet. If the TTL or hop limit is initially zero or decrementing would make it so, no decrement occurs, as packets reaching TTL zero must be rejected. Instead, a ``packet-in'' message with reason code OFPR_INVALID_TTL is sent to each connected controller that has enabled receiving them, if any. Processing the current set of actions then stops. However, if the current set of actions was reached through ``resubmit'' then remaining actions in outer levels resume processing.
This action also optionally supports the ability to specify a list of valid controller ids. Each of the controllers in the list will receive the ``packet_in'' message only if they have registered to receive the invalid ttl packets. If controller ids are not specified, the ``packet_in'' message will be sent only to the controllers having controller id zero which have registered for the invalid ttl packets.
Set the label of the outer MPLS label stack entry of a packet. label should be a 20-bit value that is decimal by default; use a 0x prefix to specify them in hexadecimal.
Set the traffic-class of the outer MPLS label stack entry of a packet. tc should be a in the range 0 to 7 inclusive.
Set the TTL of the outer MPLS label stack entry of a packet. ttl should be in the range 0 to 255 inclusive.
Decrement TTL of the outer MPLS label stack entry of a packet. If the TTL is initially zero or decrementing would make it so, no decrement occurs. Instead, a ``packet-in'' message with reason code OFPR_INVALID_TTL is sent to the main controller (id zero), if it has enabled receiving them. Processing the current set of actions then stops. However, if the current set of actions was reached through ``resubmit'' then remaining actions in outer levels resume processing.
Decrement TTL of the outer NSH header of a packet. If the TTL is initially zero or decrementing would make it so, no decrement occurs. Instead, a ``packet-in'' message with reason code OFPR_INVALID_TTL is sent to the main controller (id zero), if it has enabled receiving them. Processing the current set of actions then stops. However, if the current set of actions was reached through ``resubmit'' then remaining actions in outer levels resume processing.
Does nothing at all. Any number of bytes represented as hex digits hh may be included. Pairs of hex digits may be separated by periods for readability. The note action's format doesn't include an exact length for its payload, so the provided bytes will be padded on the right by enough bytes with value 0 to make the total number 6 more than a multiple of 8.
Copies the named bits from field src to field dst. src and dst may be NXM field names as defined in nicira-ext.h, e.g. NXM_OF_UDP_SRC or NXM_NX_REG0, or a match field name, e.g. reg0. Each start and end pair, which are inclusive, must specify the same number of bits and must fit within its respective field. Shorthands for [start..end] exist: use [bit] to specify a single bit or [] to specify an entire field (in the latter case the brackets can also be left off).
Examples: move:NXM_NX_REG0[0..5]->NXM_NX_REG1[26..31] copies the six bits numbered 0 through 5, inclusive, in register 0 into bits 26 through 31, inclusive; move:reg0[0..15]->vlan_tci copies the least significant 16 bits of register 0 into the VLAN TCI field.
In OpenFlow 1.0 through 1.4, move ordinarily uses an Open vSwitch extension to OpenFlow. In OpenFlow 1.5, move uses the OpenFlow 1.5 standard copy_field action. The ONF has also made copy_field available as an extension to OpenFlow 1.3. Open vSwitch 2.4 and later understands this extension and uses it if a controller uses it, but for backward compatibility with older versions of Open vSwitch, ovs-ofctl does not use it.

Loads a literal value into a field or part of a field. With set_field, value and the optional mask are given in the customary syntax for field dst, which is expressed as a field name. For example, set_field:00:11:22:33:44:55->eth_src sets the Ethernet source address to 00:11:22:33:44:55. With load, value must be an integer value (in decimal or prefixed by 0x for hexadecimal) and dst can also be the NXM or OXM name for the field. For example, load:0x001122334455->OXM_OF_ETH_SRC[] has the same effect as the prior set_field example.
The two forms exist for historical reasons. Open vSwitch 1.1 introduced NXAST_REG_LOAD as a Nicira extension to OpenFlow 1.0 and used load to express it. Later, OpenFlow 1.2 introduced a standard OFPAT_SET_FIELD action that was restricted to loading entire fields, so Open vSwitch added the form set_field with this restriction. OpenFlow 1.5 extended OFPAT_SET_FIELD to the point that it became a superset of NXAST_REG_LOAD. Open vSwitch translates either syntax as necessary for the OpenFlow version in use: in OpenFlow 1.0 and 1.1, NXAST_REG_LOAD; in OpenFlow 1.2, 1.3, and 1.4, NXAST_REG_LOAD for load or for loading a subfield, OFPAT_SET_FIELD otherwise; and OpenFlow 1.5 and later, OFPAT_SET_FIELD.

These Open vSwitch extension actions act on bits start to end, inclusive, in the named field, pushing or popping the bits on a general-purpose stack of fields or subfields. Controllers can use this stack for saving and restoring data or metadata around resubmit actions, for swapping or rearranging data and metadata, or for other purposes. Any data or metadata field, or part of one, may be pushed, and any modifiable field or subfield may be popped.
The number of bits pushed in a stack entry do not have to match the number of bits later popped from that entry. If more bits are popped from an entry than were pushed, then the entry is conceptually left-padded with 0-bits as needed. If fewer bits are popped than pushed, then bits are conceptually trimmed from the left side of the entry.
The stack's size is intended to have a large enough limit that ``normal'' use will not pose problems. Stack overflow or underflow is an error that causes action execution to stop.
Example: push:NXM_NX_REG2[0..5] or push:reg2[0..5] push the value stored in register 2 bits 0 through 5, inclusive, on the internal stack, and pop:NXM_NX_REG2[0..5] or pop:reg2[0..5] pops the value from top of the stack and sets register 2 bits 0 through 5, inclusive, based on bits 0 through 5 from the value just popped.
Hashes fields using basis as a universal hash parameter, then the applies multipath link selection algorithm (with parameter arg) to choose one of n_links output links numbered 0 through n_links minus 1, and stores the link into dst[start..end], which must be an NXM field as described above.
fields must be one of the following:
Hashes Ethernet source address only.
Hashes Ethernet source, destination, and type, VLAN ID, IPv4/IPv6 source, destination, and protocol, and TCP or SCTP (but not UDP) ports. The hash is computed so that pairs of corresponding flows in each direction hash to the same value, in environments where L2 paths are the same in each direction. UDP ports are not included in the hash to support protocols such as VXLAN that use asymmetric ports in each direction.
Hashes IPv4/IPv6 source, destination, and protocol, and TCP or SCTP (but not UDP) ports. Like symmetric_l4, this is a symmetric hash, but by excluding L2 headers it is more effective in environments with asymmetric L2 paths (e.g. paths involving VRRP IP addresses on a router). Not an effective hash function for protocols other than IPv4 and IPv6, which hash to a constant zero.
Like symmetric_l3l4+udp, but UDP ports are included in the hash. This is a more effective hash when asymmetric UDP protocols such as VXLAN are not a consideration.
Hashes Network source address only.
Hashes Network destination address only.
algorithm must be one of modulo_n, hash_threshold, hrw, and iter_hash. Only the iter_hash algorithm uses arg.
Refer to nicira-ext.h for more details.
Hashes fields using basis as a universal hash parameter, then applies the bundle link selection algorithm to choose one of the listed slaves represented as slave_type. Currently the only supported slave_type is ofport. Thus, each s1 through sN should be an OpenFlow port number. Outputs to the selected slave.
Currently, fields must be either eth_src, symmetric_l4, symmetric_l3l4, symmetric_l3l4+udp, nw_src, or nw_dst, and algorithm must be one of hrw and active_backup.
Example: bundle(eth_src,0,hrw,ofport,slaves:4,8) uses an Ethernet source hash with basis 0, to select between OpenFlow ports 4 and 8 using the Highest Random Weight algorithm.
Refer to nicira-ext.h for more details.
Has the same behavior as the bundle action, with one exception. Instead of outputting to the selected slave, it writes its selection to dst[start..end], which must be an NXM field as described above.
Example: bundle_load(eth_src, 0, hrw, ofport, NXM_NX_REG0[], slaves:4, 8) uses an Ethernet source hash with basis 0, to select between OpenFlow ports 4 and 8 using the Highest Random Weight algorithm, and writes the selection to NXM_NX_REG0[]. Also the match field name can be used, for example, instead of 'NXM_NX_REG0' the name 'reg0' can be used. When the while field is indicated the empty brackets can also be left off.
Refer to nicira-ext.h for more details.
This action adds or modifies a flow in an OpenFlow table, similar to ovs-ofctl --strict mod-flows. The arguments specify the flow's match fields, actions, and other properties, as follows. At least one match criterion and one action argument should ordinarily be specified.




These arguments have the same meaning as in the usual ovs-ofctl flow syntax.

Adds a fin_timeout action with the specified arguments to the new flow. This feature was added in Open vSwitch 1.5.90.
The table in which the new flow should be inserted. Specify a decimal number between 0 and 254 or (unless --no-names is specified) a name. The default, if table is unspecified, is table 1.
This flag enables deletion of the learned flows when the flow with the learn action is removed. Specifically, when the last learn action with this flag and particular table and cookie values is removed, the switch deletes all of the flows in the specified table with the specified cookie.
This flag was added in Open vSwitch 2.4.
If the number of flows in table table with cookie id cookie exceeds number, a new flow will not be learned by this action. By default there's no limit. limit=0 is a long-hand for no limit.
This flag was added in Open vSwitch 2.8.
If learning failed (because the number of flows exceeds limit), the action sets field[bit] to 0, otherwise it will be set to 1. field[bit] must be a single bit.
This flag was added in Open vSwitch 2.8.


Adds a match criterion to the new flow.
The first form specifies that field must match the literal value, e.g. dl_type=0x0800. All of the fields and values for ovs-ofctl flow syntax are available with their usual meanings. Shorthand notation matchers (e.g. ip in place of dl_type=0x0800) are not currently implemented.
The second form specifies that field[start..end] in the new flow must match src[start..end] taken from the flow currently being processed. For example, NXM_OF_UDP_DST[]=NXM_OF_UDP_SRC[] on a TCP packet for which the UDP src port is 53, creates a flow which matches NXM_OF_UDP_DST[]=53.
The third form is a shorthand for the second form. It specifies that field[start..end] in the new flow must match the same field[start..end] taken from the flow currently being processed. For example, NXM_OF_TCP_DST[] on a TCP packet for which the TCP dst port is 80, creates a flow which matches NXM_OF_TCP_DST[]=80.

Adds a load action to the new flow.
The first form loads the literal value into bits start through end, inclusive, in field dst. Its syntax is the same as the load action described earlier in this section.
The second form loads src[start..end], a value from the flow currently being processed, into bits start through end, inclusive, in field dst.
Add an output action to the new flow's actions, that outputs to the OpenFlow port taken from field[start..end], which must be an NXM field as described above.
Clears all the actions in the action set immediately.
Add the specific actions to the action set. The syntax of actions is the same as in the actions= field. The action set is carried between flow tables and then executed at the end of the pipeline.
The actions in the action set are applied in the following order, as required by the OpenFlow specification, regardless of the order in which they were added to the action set. Except as specified otherwise below, the action set only holds at most a single action of each type. When more than one action of a single type is written to the action set, the one written later replaces the earlier action:
1.
strip_vlan
pop_mpls
2.
decap
3.
encap
4.
push_mpls
5.
push_vlan
6.
dec_ttl
dec_mpls_ttl
dec_nsh_ttl
7.
load
move
mod_dl_dst
mod_dl_src
mod_nw_dst
mod_nw_src
mod_nw_tos
mod_nw_ecn
mod_nw_ttl
mod_tp_dst
mod_tp_src
mod_vlan_pcp
mod_vlan_vid
set_field
set_tunnel
set_tunnel64
The action set can contain any number of these actions, with cumulative effect. They will be applied in the order as added. That is, when multiple actions modify the same part of a field, the later modification takes effect, and when they modify different parts of a field (or different fields), then both modifications are applied.
8.
set_queue
9.
group
output
resubmit
If more than one of these actions is present, then the one listed earliest above is executed and the others are ignored, regardless of the order in which they were added to the action set. (If none of these actions is present, the action set has no real effect, because the modified packet is not sent anywhere and thus the modifications are not visible.)
Only the actions listed above may be written to the action set. encap, decap and dec_nsh_ttl actions are nonstandard.
Updates the metadata field for the flow. If mask is omitted, the metadata field is set exactly to value; if mask is specified, then a 1-bit in mask indicates that the corresponding bit in the metadata field will be replaced with the corresponding bit from value. Both value and mask are 64-bit values that are decimal by default; use a 0x prefix to specify them in hexadecimal.
Apply the meter_id before any other actions. If a meter band rate is exceeded, the packet may be dropped, or modified, depending on the meter band type. See the description of the Meter Table Commands, above, for more details.
Jumps to table as the next table in the process pipeline. The table may be a number between 0 and 254 or (unless --no-names is specified) a name.
This action changes the idle timeout or hard timeout, or both, of this OpenFlow rule when the rule matches a TCP packet with the FIN or RST flag. When such a packet is observed, the action reduces the rule's timeouts to those specified on the action. If the rule's existing timeout is already shorter than the one that the action specifies, then that timeout is unaffected.
argument takes the following forms:
Causes the flow to expire after the given number of seconds of inactivity.
Causes the flow to expire after the given number of seconds, regardless of activity. (seconds specifies time since the flow's creation, not since the receipt of the FIN or RST.)
This action was added in Open vSwitch 1.5.90.
Samples packets and sends one sample for every sampled packet.
argument takes the following forms:
The number of sampled packets out of 65535. Must be greater or equal to 1.
The unsigned 32-bit integer identifier of the set of sample collectors to send sampled packets to. Defaults to 0.
When sending samples to IPFIX collectors, the unsigned 32-bit integer Observation Domain ID sent in every IPFIX flow record. Defaults to 0.
When sending samples to IPFIX collectors, the unsigned 32-bit integer Observation Point ID sent in every IPFIX flow record. Defaults to 0.
Sample packets on port, which should be the ingress or egress port. This option, which was added in Open vSwitch 2.5.90, allows the IPFIX implementation to export egress tunnel information.

Specifies explicitly that the packet is being sampled on ingress to or egress from the switch. IPFIX reports sent by Open vSwitch before version 2.5.90 did not include a direction. From 2.5.90 until 2.6.90, IPFIX reports inferred a direction from sampling_port: if it was the packet's output port, then the direction was reported as egress, otherwise as ingress. Open vSwitch 2.6.90 introduced these options, which allow the inferred direction to be overridden. This is particularly useful when the ingress (or egress) port is not a tunnel.
Refer to ovs-vswitchd.conf.db(5) for more details on configuring sample collector sets.
This action was added in Open vSwitch 1.10.90.
This action causes Open vSwitch to immediately halt execution of further actions. Those actions which have already been executed are unaffected. Any further actions, including those which may be in other tables, or different levels of the resubmit call stack, are ignored. Actions in the action set is still executed (specify clear_actions before exit to discard them).
This action allows for sophisticated ``conjunctive match'' flows. Refer to CONJUNCTIVE MATCH FIELDS in ovs-fields(7) for details.
The conjunction action and conj_id field were introduced in Open vSwitch 2.4.
Executes each nested action, saving much of the packet and pipeline state beforehand and then restoring it afterward. The state that is saved and restored includes all flow data and metadata (including, for example, ct_state), the stack accessed by push and pop actions, and the OpenFlow action set.
This action was added in Open vSwitch 2.6.90.
Encapsulates the packet with a new packet header, e.g., ethernet or nsh.
Used to specify encapsulation header type.
Used to specify the initial value for the property in the encapsulation header.
Used to specify the initial value for the TLV (Type Length Value) in the encapsulation header.
For example, encap(ethernet) will encapsulate the L3 packet with Ethernet header.
encap(nsh(md_type=1)) will encapsulate the packet with nsh header and nsh metadata type 1.
encap(nsh(md_type=2,tlv(0x1000,10,0x12345678))) will encapsulate the packet with nsh header and nsh metadata type 2, and the nsh TLV with class 0x1000 and type 10 is set to 0x12345678.
prop=value is just used to set some necessary fields for encapsulation header initialization. Other fields in the encapsulation header must be set by set_field action. New encapsulation header implementation must add new match fields and corresponding set action in order that set_field action can change the fields in the encapsulation header on demand.
encap(nsh(md_type=1)), set_field:0x1234->nsh_spi,set_field:0x11223344->nsh_c1 is an example to encapsulate nsh header and set nsh spi and c1.
This action was added in Open vSwitch 2.8.
Decapsulates the outer packet header.
It is optional and used to specify the outer header type of the decapsulated packet. namespace is 0 for Ethernet packet, 1 for L3 packet, type is L3 protocol type, e.g., 0x894f for nsh, 0x0 for Ethernet.
By default, decap() will decapsulate the outer packet header according to the packet header type, if packet_type(ns=namespace,type=type) is given, it will decapsulate the given packet header, it will fail if the actual outer packet header type is not of packet_type(ns=namespace,type=type).
This action was added in Open vSwitch 2.8.

An opaque identifier called a cookie can be used as a handle to identify a set of flows:

A cookie can be associated with a flow using the add-flow, add-flows, and mod-flows commands. value can be any 64-bit number and need not be unique among flows. If this field is omitted, a default cookie value of 0 is used.
When using NXM, the cookie can be used as a handle for querying, modifying, and deleting flows. value and mask may be supplied for the del-flows, mod-flows, dump-flows, and dump-aggregate commands to limit matching cookies. A 1-bit in mask indicates that the corresponding bit in cookie must match exactly, and a 0-bit wildcards that bit. A mask of -1 may be used to exactly match a cookie.
The mod-flows command can update the cookies of flows that match a cookie by specifying the cookie field twice (once with a mask for matching and once without to indicate the new value):
Change all flows' cookies to 1 and change their actions to normal.
Update cookies with a value of 1 to 2 and change their actions to normal.
The ability to match on cookies was added in Open vSwitch 1.5.0.

The following additional field sets the priority for flows added by the add-flow and add-flows commands. For mod-flows and del-flows when --strict is specified, priority must match along with the rest of the flow specification. For mod-flows without --strict, priority is only significant if the command creates a new flow, that is, non-strict mod-flows does not match on priority and will not change the priority of existing flows. Other commands do not allow priority to be specified.

The priority at which a wildcarded entry will match in comparison to others. value is a number between 0 and 65535, inclusive. A higher value will match before a lower one. An exact-match entry will always have priority over an entry containing wildcards, so it has an implicit priority value of 65535. When adding a flow, if the field is not specified, the flow's priority will default to 32768.
OpenFlow leaves behavior undefined when two or more flows with the same priority can match a single packet. Some users expect ``sensible'' behavior, such as more specific flows taking precedence over less specific flows, but OpenFlow does not specify this and Open vSwitch does not implement it. Users should therefore take care to use priorities to ensure the behavior that they expect.

The add-flow, add-flows, and mod-flows commands support the following additional options. These options affect only new flows. Thus, for add-flow and add-flows, these options are always significant, but for mod-flows they are significant only if the command creates a new flow, that is, their values do not update or affect existing flows.

Causes the flow to expire after the given number of seconds of inactivity. A value of 0 (the default) prevents a flow from expiring due to inactivity.
Causes the flow to expire after the given number of seconds, regardless of activity. A value of 0 (the default) gives the flow no hard expiration deadline.
Sets the importance of a flow. The flow entry eviction mechanism can use importance as a factor in deciding which flow to evict. A value of 0 (the default) makes the flow non-evictable on the basis of importance. Specify a value between 0 and 65535.
Only OpenFlow 1.4 and later support importance.
Marks the flow with a flag that causes the switch to generate a ``flow removed'' message and send it to interested controllers when the flow later expires or is removed.
Forces the switch to check that the flow match does not overlap that of any different flow with the same priority in the same table. (This check is expensive so it is best to avoid it.)
When this flag is specified on a flow being added to a switch, and the switch already has a flow with an identical match, an OpenFlow 1.2 (or later) switch resets the flow's packet and byte counters to 0. Without the flag, the packet and byte counters are preserved.
OpenFlow 1.0 and 1.1 switches always reset counters in this situation, as if reset_counts were always specified.
Open vSwitch 1.10 added support for reset_counts.

Adding these flags to a flow advises an OpenFlow 1.3 (or later) switch that the controller does not need packet or byte counters, respectively, for the flow. Some switch implementations might achieve higher performance or reduce resource consumption when these flags are used. These flags provide no benefit to the Open vSwitch software switch implementation.
OpenFlow 1.2 and earlier do not support these flags.
Open vSwitch 1.10 added support for no_packet_counts and no_byte_counts.

The dump-flows, dump-aggregate, del-flow and del-flows commands support these additional optional fields:

If set, a matching flow must include an output action to port, which must be an OpenFlow port number or name (e.g. local).
If set, a matching flow must include an group action naming group, which must be an OpenFlow group number. This field is supported in Open vSwitch 2.5 and later and requires OpenFlow 1.1 or later.

The dump-tables and dump-aggregate commands print information about the entries in a datapath's tables. Each line of output is a flow entry as described in Flow Syntax, above, plus some additional fields:

The time, in seconds, that the entry has been in the table. secs includes as much precision as the switch provides, possibly to nanosecond resolution.
The number of packets that have matched the entry.
The total number of bytes from packets that have matched the entry.

The following additional fields are included only if the switch is Open vSwitch 1.6 or later and the NXM flow format is used to dump the flow (see the description of the --flow-format option below). The values of these additional fields are approximations only and in particular idle_age will sometimes become nonzero even for busy flows.

The integer number of seconds since the flow was added or modified. hard_age is displayed only if it differs from the integer part of duration. (This is separate from duration because mod-flows restarts the hard_timeout timer without zeroing duration.)
The integer number of seconds that have passed without any packets passing through the flow.

ovs-ofctl bundle command accepts packet-outs to be specified in the bundle file. Each packet-out comprises of a series of field=value assignments, separated by commas or white space. (Embedding spaces into a packet-out description normally requires quoting to prevent the shell from breaking the description into multiple arguments.). Unless noted otherwise only the last instance of each field is honoured. This same syntax is also supported by the ovs-ofctl packet-out command.

The port number to be considered the in_port when processing actions. This can be any valid OpenFlow port number, or any of the LOCAL, CONTROLLER, or NONE. This field is required.

Optionally, user can specify a list of pipeline fields for a packet-out message. The supported pipeline fields includes tunnel fields and register fields as defined in ovs-fields(7).

The actual packet to send, expressed as a string of hexadecimal bytes. This field is required.

The syntax of actions are identical to the actions= field described in Flow Syntax above. Specifying actions= is optional, but omitting actions is interpreted as a drop, so the packet will not be sent anywhere from the switch. actions must be specified at the end of each line, like for flow mods.

Some ovs-ofctl commands accept an argument that describes a group or groups. Such flow descriptions comprise a series field=value assignments, separated by commas or white space. (Embedding spaces into a group description normally requires quoting to prevent the shell from breaking the description into multiple arguments.). Unless noted otherwise only the last instance of each field is honoured.

The integer group id of group. When this field is specified in del-groups or dump-groups, the keyword "all" may be used to designate all groups. This field is required.

The type of the group. The add-group, add-groups and mod-groups commands require this field. It is prohibited for other commands. The following keywords designated the allowed types:
Execute all buckets in the group.
Execute one bucket in the group, balancing across the buckets according to their weights. To select a bucket, for each live bucket, Open vSwitch hashes flow data with the bucket ID and multiplies by the bucket weight to obtain a ``score,'' and then selects the bucket with the highest score. Use selection_method to control the flow data used for selection.
Executes the one bucket in the group.

Executes the first live bucket in the group which is associated with a live port or group.

The bucket to operate on. The insert-buckets and remove-buckets commands require this field. It is prohibited for other commands. id may be an integer or one of the following keywords:
Operate on all buckets in the group. Only valid when used with the remove-buckets command in which case the effect is to remove all buckets from the group.
Operate on the first bucket present in the group. In the case of the insert-buckets command the effect is to insert new bucets just before the first bucket already present in the group; or to replace the buckets of the group if there are no buckets already present in the group. In the case of the remove-buckets command the effect is to remove the first bucket of the group; or do nothing if there are no buckets present in the group.
Operate on the last bucket present in the group. In the case of the insert-buckets command the effect is to insert new bucets just after the last bucket already present in the group; or to replace the buckets of the group if there are no buckets already present in the group. In the case of the remove-buckets command the effect is to remove the last bucket of the group; or do nothing if there are no buckets present in the group.
If id is an integer then it should correspond to the bucket_id of a bucket present in the group. In case of the insert-buckets command the effect is to insert buckets just before the bucket in the group whose bucket_id is id. In case of the iremove-buckets command the effect is to remove the in the group whose bucket_id is id. It is an error if there is no bucket persent group in whose bucket_id is id.

The selection method used to select a bucket for a select group. This is a string of 1 to 15 bytes in length known to lower layers. This field is optional for add-group, add-groups and mod-group commands on groups of type select. Prohibited otherwise. If no selection method is specified, Open vSwitch up to release 2.9 applies the hash method with default fields. From 2.10 onwards Open vSwitch defaults to the dp_hash method with symmetric L3/L4 hash algorithm, unless the weighted group buckets cannot be mapped to a maximum of 64 dp_hash values with sufficient accuracy. In those rare cases Open vSwitch 2.10 and later fall back to the hash method with the default set of hash fields.
Use a datapath computed hash value. The hash algorithm varies accross different datapath implementations. dp_hash uses the upper 32 bits of the selection_method_param as the datapath hash algorithm selector. The supported values are 0 (corresponding to hash computation over the IP 5-tuple) and 1 (corresponding to a symmetric hash computation over the IP 5-tuple). Selecting specific fields with the fields option is not supported with dp_hash). The lower 32 bits are used as the hash basis.
Using dp_hash has the advantage that it does not require the generated datapath flows to exact match any additional packet header fields. For example, even if multiple TCP connections thus hashed to different select group buckets have different source port numbers, generally all of them would be handled with a small set of already established datapath flows, resulting in less latency for TCP SYN packets. The downside is that the shared datapath flows must match each packet twice, as the datapath hash value calculation happens only when needed, and a second match is required to match some bits of its value. This double-matching incurs a small additional latency cost for each packet, but this latency is orders of magnitude less than the latency of creating new datapath flows for new TCP connections.
Use a hash computed over the fields specified with the fields option, see below. If no hash fields are specified, hash defaults to a symmetric hash over the combination of MAC addresses, VLAN tags, Ether type, IP addresses and L4 port numbers. hash uses the selection_method_param as the hash basis.
Note that the hashed fields become exact matched by the datapath flows. For example, if the TCP source port is hashed, the created datapath flows will match the specific TCP source port value present in the packet received. Since each TCP connection generally has a different source port value, a separate datapath flow will be need to be inserted for each TCP connection thus hashed to a select group bucket.
This option uses a Netronome OpenFlow extension which is only supported when using Open vSwitch 2.4 and later with OpenFlow 1.5 and later.

64-bit integer parameter to the selection method selected by the selection_method field. The parameter's use is defined by the lower-layer that implements the selection_method. It is optional if the selection_method field is specified as a non-empty string. Prohibited otherwise. The default value is zero.
This option uses a Netronome OpenFlow extension which is only supported when using Open vSwitch 2.4 and later with OpenFlow 1.5 and later.


The field parameters to selection method selected by the selection_method field. The syntax is described in Flow Syntax with the additional restrictions that if a value is provided it is treated as a wildcard mask and wildcard masks following a slash are prohibited. The pre-requisites of fields must be provided by any flows that output to the group. The use of the fields is defined by the lower-layer that implements the selection_method. They are optional if the selection_method field is specified as ``hash', prohibited otherwise. The default is no fields.
This option will use a Netronome OpenFlow extension which is only supported when using Open vSwitch 2.4 and later with OpenFlow 1.5 and later.

The add-group, add-groups and mod-group commands require at least one bucket field. Bucket fields must appear after all other fields. Multiple bucket fields to specify multiple buckets. The order in which buckets are specified corresponds to their order in the group. If the type of the group is "indirect" then only one group may be specified. bucket_parameters consists of a list of field=value assignments, separated by commas or white space followed by a comma-separated list of actions. The fields for bucket_parameters are:
The 32-bit integer group id of the bucket. Values greater than 0xffffff00 are reserved. This field was added in Open vSwitch 2.4 to conform with the OpenFlow 1.5 specification. It is not supported when earlier versions of OpenFlow are used. Open vSwitch will automatically allocate bucket ids when they are not specified.
The syntax of actions are identical to the actions= field described in Flow Syntax above. Specifying actions= is optional, any unknown bucket parameter will be interpreted as an action.
The relative weight of the bucket as an integer. This may be used by the switch during bucket select for groups whose type is select.
Port used to determine liveness of group. This or the watch_group field is required for groups whose type is ff or fast_failover.
Group identifier of group used to determine liveness of group. This or the watch_port field is required for groups whose type is ff or fast_failover.

The meter table commands accept an argument that describes a meter. Such meter descriptions comprise a series field=value assignments, separated by commas or white space. (Embedding spaces into a group description normally requires quoting to prevent the shell from breaking the description into multiple arguments.). Unless noted otherwise only the last instance of each field is honoured.

The identifier for the meter. An integer is used to specify a user-defined meter. In addition, the keywords "all", "controller", and "slowpath", are also supported as virtual meters. The "controller" and "slowpath" virtual meters apply to packets sent to the controller and to the OVS userspace, respectively.
When this field is specified in del-meter, dump-meter, or meter-stats, the keyword "all" may be used to designate all meters. This field is required, except for meter-stats, which dumps all stats when this field is not specified.

The unit for the rate and burst_size band parameters. kbps specifies kilobits per second, and pktps specifies packets per second. A unit is required for the add-meter and mod-meter commands.

If set, enables burst support for meter bands through the burst_size parameter.

If set, enables the collection of meter and band statistics.

The add-meter and mod-meter commands require at least one band specification. Bands must appear after all other fields.
The type of the meter band. This keyword starts a new band specification. Each band specifies a rate above which the band is to take some action. The action depends on the band type. If multiple bands' rate is exceeded, then the band with the highest rate among the exceeded bands is selected. The following keywords designate the allowed meter band types:
Drop packets exceeding the band's rate limit.
The relative rate limit for this band, in kilobits per second or packets per second, depending on whether kbps or pktps was specified.
If burst is specified for the meter entry, configures the maximum burst allowed for the band in kilobits or packets, depending on whether kbps or pktps was specified. If unspecified, the switch is free to select some reasonable value depending on its configuration.

Uses strict matching when running flow modification commands.

Every OpenFlow port has a name and a number, and every OpenFlow flow table has a number and sometimes a name. By default, ovs-ofctl commands accept both port and table names and numbers, and they display port and table names if ovs-ofctl is running on an interactive console, numbers otherwise. With --names, ovs-ofctl commands both accept and display port and table names; with --no-names, commands neither accept nor display port and table names.
If a port or table name contains special characters or might be confused with a keyword within a flow, it may be enclosed in double quotes (escaped from the shell). If necessary, JSON-style escape sequences may be used inside quotes, as specified in RFC 7159. When it displays port and table names, ovs-ofctl quotes any name that does not start with a letter followed by letters or digits.
Open vSwitch added support for port names and these options. Open vSwitch 2.10 added support for table names. Earlier versions always behaved as if --no-names were specified.
Open vSwitch does not place its own limit on the length of port names, but OpenFlow 1.0 to 1.5 limit port names to 15 bytes and OpenFlow 1.6 limits them to 63 bytes. Because ovs-ofctl uses OpenFlow to retrieve the mapping between port names and numbers, names longer than this limit will be truncated for both display and acceptance. Truncation can also cause long names that are different to appear to be the same; when a switch has two ports with the same (truncated) name, ovs-ofctl refuses to display or accept the name, using the number instead.
OpenFlow and Open vSwitch limit table names to 32 bytes.

The dump-flows command by default, or with --stats, includes flow duration, packet and byte counts, and idle and hard age in its output. With --no-stats, it omits all of these, as well as cookie values and table IDs if they are zero.
Do not execute read/write commands.
Execute flow mods as an OpenFlow 1.4 atomic bundle transaction.
  • Within a bundle, all flow mods are processed in the order they appear and as a single atomic transaction, meaning that if one of them fails, the whole transaction fails and none of the changes are made to the switch's flow table, and that each given datapath packet traversing the OpenFlow tables sees the flow tables either as before the transaction, or after all the flow mods in the bundle have been successfully applied.
  • The beginning and the end of the flow table modification commands in a bundle are delimited with OpenFlow 1.4 bundle control messages, which makes it possible to stream the included commands without explicit OpenFlow barriers, which are otherwise used after each flow table modification command. This may make large modifications execute faster as a bundle.
  • Bundles require OpenFlow 1.4 or higher. An explicit -O OpenFlow14 option is not needed, but you may need to enable OpenFlow 1.4 support for OVS by setting the OVSDB protocols column in the bridge table.

Sets the OpenFlow protocol versions that are allowed when establishing an OpenFlow session.
These protocol versions are enabled by default:
•
OpenFlow10, for OpenFlow 1.0.

The following protocol versions are generally supported, but for compatibility with older versions of Open vSwitch they are not enabled by default:

  • OpenFlow11, for OpenFlow 1.1.
  • OpenFlow12, for OpenFlow 1.2.
  • OpenFlow13, for OpenFlow 1.3.
  • OpenFlow14, for OpenFlow 1.4.
Support for the following protocol versions is provided for testing and development purposes. They are not enabled by default:
  • OpenFlow15, for OpenFlow 1.5.
  • OpenFlow16, for OpenFlow 1.6.

ovs-ofctl supports the following individual flow formats, any number of which may be listed as format:
This is the standard OpenFlow 1.0 flow format. All OpenFlow switches and all versions of Open vSwitch support this flow format.
This is the standard OpenFlow 1.0 flow format plus a Nicira extension that allows ovs-ofctl to specify the flow table in which a particular flow should be placed. Open vSwitch 1.2 and later supports this flow format.
This Nicira extension to OpenFlow is flexible and extensible. It supports all of the Nicira flow extensions, such as tun_id and registers. Open vSwitch 1.1 and later supports this flow format.
This combines Nicira Extended match with the ability to place a flow in a specific table. Open vSwitch 1.2 and later supports this flow format.




These are the standard OXM (OpenFlow Extensible Match) flow format in OpenFlow 1.2 and later.
ovs-ofctl also supports the following abbreviations for collections of flow formats:
Any supported flow format.
OpenFlow10-table_id or OpenFlow10+table_id.
NXM-table_id or NXM+table_id.
OXM-OpenFlow12, OXM-OpenFlow13, or OXM-OpenFlow14.
For commands that modify the flow table, ovs-ofctl by default negotiates the most widely supported flow format that supports the flows being added. For commands that query the flow table, ovs-ofctl by default uses the most advanced format supported by the switch.
This option, where format is a comma-separated list of one or more of the formats listed above, limits ovs-ofctl's choice of flow format. If a command cannot work as requested using one of the specified flow formats, ovs-ofctl will report a fatal error.

ovs-ofctl supports the following ``packet-in'' formats, in order of increasing capability:
This uses the OFPT_PACKET_IN message, the standard ``packet-in'' message for any given OpenFlow version. Every OpenFlow switch that supports a given OpenFlow version supports this format.
This uses the NXT_PACKET_IN message, which adds many of the capabilities of the OpenFlow 1.1 and later ``packet-in'' messages before those OpenFlow versions were available in Open vSwitch. Open vSwitch 1.1 and later support this format. Only Open vSwitch 2.6 and later, however, support it for OpenFlow 1.1 and later (but there is little reason to use it with those versions of OpenFlow).
This uses the NXT_PACKET_IN2 message, which is extensible and should avoid the need to define new formats later. In particular, this format supports passing arbitrary user-provided data to a controller using the userdata option on the controller action. Open vSwitch 2.6 and later support this format.
Without this option, ovs-ofctl prefers nxt_packet_in2 if the switch supports it. Otherwise, if OpenFlow 1.0 is in use, ovs-ofctl prefers nxt_packet_in if the switch supports it. Otherwise, ovs-ofctl falls back to the standard packet-in format. When this option is specified, ovs-ofctl insists on the selected format. If the switch does not support the requested format, ovs-ofctl will report a fatal error.
Before version 2.6, Open vSwitch called standard format openflow10 and nxt_packet_in format nxm, and ovs-ofctl still accepts these names as synonyms. (The name openflow10 was a misnomer because this format actually varies from one OpenFlow version to another; it is not consistently OpenFlow 1.0 format. Similarly, when nxt_packet_in2 was introduced, the name nxm became confusing because it also uses OXM/NXM.)
This option affects only the monitor command.
Print a timestamp before each received packet. This option only affects the monitor, snoop, and ofp-parse-pcap commands.

Increases the verbosity of OpenFlow messages printed and logged by ovs-ofctl commands. Specify this option more than once to increase verbosity further.

Display output sorted by flow field in ascending (--sort) or descending (--rsort) order, where field is any of the fields that are allowed for matching or priority to sort by priority. When field is omitted, the output is sorted by priority. Specify these options multiple times to sort by multiple fields.
Any given flow will not necessarily specify a value for a given field. This requires special treatement:
  • A flow that does not specify any part of a field that is used for sorting is sorted after all the flows that do specify the field. For example, --sort=tcp_src will sort all the flows that specify a TCP source port in ascending order, followed by the flows that do not specify a TCP source port at all.
  • A flow that only specifies some bits in a field is sorted as if the wildcarded bits were zero. For example, --sort=nw_src would sort a flow that specifies nw_src=192.168.0.0/24 the same as nw_src=192.168.0.0.
These options currently affect only dump-flows output.

The following options are valid on POSIX based platforms.

Causes a file (by default, ovs-ofctl.pid) to be created indicating the PID of the running process. If the pidfile argument is not specified, or if it does not begin with /, then it is created in /var/run/openvswitch.
If --pidfile is not specified, no pidfile is created.
By default, when --pidfile is specified and the specified pidfile already exists and is locked by a running process, ovs-ofctl refuses to start. Specify --overwrite-pidfile to cause it to instead overwrite the pidfile.
When --pidfile is not specified, this option has no effect.
Runs ovs-ofctl as a background process. The process forks, and in the child it starts a new session, closes the standard file descriptors (which has the side effect of disabling logging to the console), and changes its current directory to the root (unless --no-chdir is specified). After the child completes its initialization, the parent exits. ovs-ofctl detaches only when executing the monitor or snoop commands.
Creates an additional process to monitor the ovs-ofctl daemon. If the daemon dies due to a signal that indicates a programming error (SIGABRT, SIGALRM, SIGBUS, SIGFPE, SIGILL, SIGPIPE, SIGSEGV, SIGXCPU, or SIGXFSZ) then the monitor process starts a new copy of it. If the daemon dies or exits for another reason, the monitor process exits.
This option is normally used with --detach, but it also functions without it.
By default, when --detach is specified, ovs-ofctl changes its current working directory to the root directory after it detaches. Otherwise, invoking ovs-ofctl from a carelessly chosen directory would prevent the administrator from unmounting the file system that holds that directory.
Specifying --no-chdir suppresses this behavior, preventing ovs-ofctl from changing its current working directory. This may be useful for collecting core files, since it is common behavior to write core dumps into the current working directory and the root directory is not a good directory to use.
This option has no effect when --detach is not specified.
By default daemon will try to self-confine itself to work with files under well-know, at build-time whitelisted directories. It is better to stick with this default behavior and not to use this flag unless some other Access Control is used to confine daemon. Note that in contrast to other access control implementations that are typically enforced from kernel-space (e.g. DAC or MAC), self-confinement is imposed from the user-space daemon itself and hence should not be considered as a full confinement strategy, but instead should be viewed as an additional layer of security.
Causes ovs-ofctl to run as a different user specified in "user:group", thus dropping most of the root privileges. Short forms "user" and ":group" are also allowed, with current user or group are assumed respectively. Only daemons started by the root user accepts this argument.
On Linux, daemons will be granted CAP_IPC_LOCK and CAP_NET_BIND_SERVICES before dropping root privileges. Daemons that interact with a datapath, such as ovs-vswitchd, will be granted three additional capabilities, namely CAP_NET_ADMIN, CAP_NET_BROADCAST and CAP_NET_RAW. The capability change will apply even if the new user is root.
On Windows, this option is not currently supported. For security reasons, specifying this option will cause the daemon process not to start.
Sets the name of the control socket on which ovs-ofctl listens for runtime management commands (see RUNTIME MANAGEMENT COMMANDS, below). If socket does not begin with /, it is interpreted as relative to /var/run/openvswitch. If --unixctl is not used at all, the default socket is /var/run/openvswitch/ovs-ofctl.pid.ctl, where pid is ovs-ofctl's process ID.
On Windows a local named pipe is used to listen for runtime management commands. A file is created in the absolute path as pointed by socket or if --unixctl is not used at all, a file is created as ovs-ofctl.ctl in the configured OVS_RUNDIR directory. The file exists just to mimic the behavior of a Unix domain socket.
Specifying none for socket disables the control socket feature.


Specifies a PEM file containing the private key used as ovs-ofctl's identity for outgoing SSL connections.

Specifies a PEM file containing a certificate that certifies the private key specified on -p or --private-key to be trustworthy. The certificate must be signed by the certificate authority (CA) that the peer in SSL connections will use to verify it.

Specifies a PEM file containing the CA certificate that ovs-ofctl should use to verify certificates presented to it by SSL peers. (This may be the same certificate that SSL peers use to verify the certificate specified on -c or --certificate, or it may be a different one, depending on the PKI design in use.)

Disables verification of certificates presented by SSL peers. This introduces a security risk, because it means that certificates cannot be verified to be those of known trusted hosts.

Sets logging levels. Without any spec, sets the log level for every module and destination to dbg. Otherwise, spec is a list of words separated by spaces or commas or colons, up to one from each category below:
  • A valid module name, as displayed by the vlog/list command on ovs-appctl(8), limits the log level change to the specified module.
  • syslog, console, or file, to limit the log level change to only to the system log, to the console, or to a file, respectively. (If --detach is specified, ovs-ofctl closes its standard file descriptors, so logging to the console will have no effect.)
On Windows platform, syslog is accepted as a word and is only useful along with the --syslog-target option (the word has no effect otherwise).
•
off, emer, err, warn, info, or dbg, to control the log level. Messages of the given severity or higher will be logged, and messages of lower severity will be filtered out. off filters out all messages. See ovs-appctl(8) for a definition of each log level.
Case is not significant within spec.
Regardless of the log levels set for file, logging to a file will not take place unless --log-file is also specified (see below).
For compatibility with older versions of OVS, any is accepted as a word but has no effect.

Sets the maximum logging verbosity level, equivalent to --verbose=dbg.

Sets the log pattern for destination to pattern. Refer to ovs-appctl(8) for a description of the valid syntax for pattern.

Sets the RFC5424 facility of the log message. facility can be one of kern, user, mail, daemon, auth, syslog, lpr, news, uucp, clock, ftp, ntp, audit, alert, clock2, local0, local1, local2, local3, local4, local5, local6 or local7. If this option is not specified, daemon is used as the default for the local system syslog and local0 is used while sending a message to the target provided via the --syslog-target option.
Enables logging to a file. If file is specified, then it is used as the exact name for the log file. The default log file name used if file is omitted is /var/log/openvswitch/ovs-ofctl.log.
Send syslog messages to UDP port on host, in addition to the system syslog. The host must be a numerical IP address, not a hostname.
Specify method how syslog messages should be sent to syslog daemon. Following forms are supported:
  • libc, use libc syslog() function. This is the default behavior. Downside of using this options is that libc adds fixed prefix to every message before it is actually sent to the syslog daemon over /dev/log UNIX domain socket.
  • unix:file, use UNIX domain socket directly. It is possible to specify arbitrary message format with this option. However, rsyslogd 8.9 and older versions use hard coded parser function anyway that limits UNIX domain socket use. If you want to use arbitrary message format with older rsyslogd versions, then use UDP socket to localhost IP address instead.
  • udp:ip:port, use UDP socket. With this method it is possible to use arbitrary message format also with older rsyslogd. When sending syslog messages over UDP socket extra precaution needs to be taken into account, for example, syslog daemon needs to be configured to listen on the specified UDP port, accidental iptables rules could be interfering with local syslog traffic and there are some security considerations that apply to UDP sockets, but do not apply to UNIX domain sockets.
Colorize the output (for some commands); when can be never, always, or auto (the default).

Only some commands support output coloring. Color names and default colors may change in future releases.

The environment variable OVS_COLORS can be used to specify user-defined colors and other attributes used to highlight various parts of the output. If set, its value is a colon-separated list of capabilities that defaults to ac:01;31:dr=34:le=31:pm=36:pr=35:sp=33:vl=32. Supported capabilities were initially designed for coloring flows from ovs-ofctl dump-flows switch command, and they are as follows.

SGR substring for actions= keyword in a flow. The default is a bold red text foreground.
SGR substring for drop keyword. The default is a dark blue text foreground.
SGR substring for learn= keyword in a flow. The default is a red text foreground.
SGR substring for flow match attribute names. The default is a cyan text foreground.
SGR substring for keywords in a flow that are followed by arguments inside parenthesis. The default is a magenta text foreground.
SGR substring for some special keywords in a flow, notably: table=, priority=, load:, output:, move:, group:, CONTROLLER:, set_field:, resubmit:, exit. The default is a yellow text foreground.
SGR substring for a lone flow match attribute with no field name. The default is a green text foreground.

See the Select Graphic Rendition (SGR) section in the documentation of the text terminal that is used for permitted values and their meaning as character attributes.


Prints a brief help message to the console.

Prints version information to the console.

ovs-appctl(8) can send commands to a running ovs-ofctl process. The supported commands are listed below.

Causes ovs-ofctl to gracefully terminate. This command applies only when executing the monitor or snoop commands.
Causes all subsequent output to go to file instead of stderr. This command applies only when executing the monitor or snoop commands.
Sends each ofmsg, specified as a sequence of hex digits that express an OpenFlow message, on the OpenFlow connection. This command is useful only when executing the monitor command.
Sends an OpenFlow PACKET_OUT message specified in Packet-Out Syntax, on the OpenFlow connection. See Packet-Out Syntax section for more information. This command is useful only when executing the monitor command.
Sends an OpenFlow barrier request on the OpenFlow connection and waits for a reply. This command is useful only for the monitor command.

The following examples assume that ovs-vswitchd has a bridge named br0 configured.

Prints out the switch's table stats. (This is more interesting after some traffic has passed through.)
Prints the flow entries in the switch.
ovs-ofctl add-flow table=1 priority=0 actions=flood Implements a level 2 MAC learning switch using the learn.
In this use of a learn action, the first packet from each source MAC will be sent to port 2. Subsequent packets will be output to port 3, with an idle timeout of 10 seconds. NXM field names and match field names are both accepted, e.g. NXM_NX_REG0 or reg0 for the first register, and empty brackets may be omitted.
Additional examples may be found documented as part of related sections.

ovs-fields(7), ovs-appctl(8), ovs-vswitchd(8), ovs-vswitchd.conf.db(8)

2.10.7 Open vSwitch