ovs-vswitchd(8)

NAME
ovs-vswitchd - Open vSwitch daemon

SYNOPSIS
ovs-vswitchd [database]

DESCRIPTION
A daemon that manages and controls any number of Open vSwitch switches on the local machine.

The database argument specifies how ovs-vswitchd connects to ovsdb-server. The default is unix:/var/run/openvswitch/db.sock. The following forms are accepted:

ssl:ip:port
    The specified SSL port on the host at the given ip, which must be expressed as an IP address (not a DNS name) in IPv4 or IPv6 address format. If ip is an IPv6 address, then wrap ip with square brackets, e.g.: ssl:[::1]:6640. The --private-key, --certificate, and --ca-cert options are mandatory when this form is used.

tcp:ip:port
    Connect to the given TCP port on ip, where ip can be IPv4 or IPv6 address. If ip is an IPv6 address, then wrap ip with square brackets, e.g.: tcp:[::1]:6640.

unix:file
    On POSIX, connect to the Unix domain server socket named file.

    On Windows, connect to a localhost TCP port whose value is written in file.

pssl:port[:ip]
    Listen on the given SSL port for a connection. By default, connections are not bound to a particular local IP address and it listens only on IPv4 (but not IPv6) addresses, but specifying ip limits connections to those from the given ip, either IPv4 or IPv6 address. If ip is an IPv6 address, then wrap ip with square brackets, e.g.: pssl:6640:[::1]. The --private-key, --certificate, and --ca-cert options are mandatory when this form is used.

ptcp:port[:ip]
    Listen on the given TCP port for a connection. By default, connections are not bound to a particular local IP address and it listens only on IPv4 (but not IPv6) addresses, but ip may be specified to listen only for connections to the given ip, either IPv4 or IPv6 address. If ip is an IPv6 address, then wrap ip with square brackets, e.g.: ptcp:6640:[::1].

punix:file
    On POSIX, listen on the Unix domain server socket named file for a connection.

    On Windows, listen on a kernel chosen TCP port on the localhost. The kernel chosen TCP port value is written in file.

ovs-vswitchd retrieves its configuration from database at startup. It sets up Open vSwitch datapaths and then operates switching across each bridge described in its configuration files. As the database changes, ovs-vswitchd automatically updates its configuration to match.

ovs-vswitchd switches may be configured with any of the following features:

•   L2 switching with MAC learning.

•   NIC bonding with automatic fail-over and source MAC-based TX load balancing ("SLB").

•   802.1Q VLAN support.

•   Port mirroring, with optional VLAN tagging.

•   NetFlow v5 flow logging.

•   sFlow(R) monitoring.

•   Connectivity to an external OpenFlow controller, such as NOX.

Only a single instance of ovs-vswitchd is intended to run at a time. A single ovs-vswitchd can manage any number of switch instances, up to the maximum number of supported Open vSwitch datapaths.

ovs-vswitchd does all the necessary management of Open vSwitch datapaths itself. Thus, external tools, such ovs-dpctl(8), are not needed for managing datapaths in conjunction with ovs-vswitchd, and their use to modify datapaths when ovs-vswitchd is running can interfere with its operation. (ovs-dpctl may still be useful for diagnostics.)

An Open vSwitch datapath kernel module must be loaded for ovs-vswitchd to be useful. Please refer to the INSTALL.Linux file included in the Open vSwitch distribution for instructions on how to build and load the Open vSwitch kernel module.

OPTIONS

--mlockall
    Causes ovs-vswitchd to call the mlockall() function, to attempt to lock all of its process memory into physical RAM, preventing the kernel from paging any of its memory to disk. This helps to avoid networking interruptions due to system memory pressure.

    Some systems do not support mlockall() at all, and other systems only allow privileged users, such as the superuser, to use it. ovs-vswitchd emits a log message if mlockall() is unavailable or unsuccessful.

  DPDK Options

--dpdk
    Initialize ovs-vswitchd DPDK datapath. Refer to INSTALL.DPDK for details.

  Daemon Options
The following options are valid on POSIX based platforms.

--pidfile[=pidfile]
    Causes a file (by default, ovs-vswitchd.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.

--overwrite-pidfile
    By default, when --pidfile is specified and the specified pidfile already exists and is locked by a running process, ovs-vswitchd refuses to start. Specify --overwrite-pidfile to cause it to instead overwrite the pidfile.

    When --pidfile is not specified, this option has no effect.

--detach
    Runs ovs-vswitchd 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-vswitchd detaches only after it has connected to the database, retrieved the

--monitor
    Creates an additional process to monitor the ovs-vswitchd 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.

--no-chdir
    By default, when --detach is specified, ovs-vswitchd changes its current working directory to the root directory after it detaches. Otherwise, invoking ovs-vswitchd 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-vswitchd 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.

--user
    Causes ovs-vswitchd 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 interact with datapath, such as ovs-vswitchd, will be granted two additional capabilities, namely CAP_NET_ADMIN and CAP_NET_RAW. The capability change will apply even if 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.

  Service Options
The following options are valid only on Windows platform.

--service
    Causes ovs-vswitchd to run as a service in the background. The service should already have been created through external tools like SC.exe.

--service-monitor
    Causes the ovs-vswitchd service to be automatically restarted by the Windows services manager if the service dies or exits for unexpected reasons.

    When --service is not specified, this option has no effect.

  Public Key Infrastructure Options

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

-c cert.pem
    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.

-C cacert.pem
    Specifies a PEM file containing the CA certificate that ovs-vswitchd 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.)

-C none
    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.

--bootstrap-ca-cert=cacert.pem
    When cacert.pem exists, this option has the same effect as -C or --ca-cert. If it does not exist, then ovs-vswitchd will attempt to obtain the CA certificate from the SSL peer on its first SSL connection and save it to the named PEM file. If it is successful, it will immediately drop the connection and reconnect, and from then on all SSL connections must be authenticated by a certificate signed by the CA certificate thus obtained.

    This option exposes the SSL connection to a man-in-the-middle attack obtaining the initial CA certificate, but it may be useful for bootstrapping.

    This option is only useful if the SSL peer sends its CA certificate as part of the SSL certificate chain. The SSL protocol does not require the server to send the CA certificate.

    This option is mutually exclusive with -C and --ca-cert.

  Logging Options

-v[spec]
    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-vswitchd 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.

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

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

-vFACILITY:facility
    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.

--log-file[=file]
    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-vswitchd.log.

--syslog-target=host:port
    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.

--syslog-method=method
    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.

  Other Options

--unixctl=socket
    Sets the name of the control socket on which ovs-vswitchd 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-vswitchd.pid.ctl, where pid is ovs-vswitchd's process ID.

    On Windows, uses a kernel chosen TCP port on the localhost to listen for runtime management commands. The kernel chosen TCP port value is written in a file whose absolute path is pointed by socket. If --unixctl is not used at all, the file is created as ovs-vswitchd.ctl in the configured OVS_RUNDIR directory.

    Specifying none for socket disables the control socket feature.

-h  Prints a brief help message to the console.

-V  Prints version information to the console.

RUNTIME MANAGEMENT COMMANDS
ovs-appctl(8) can send commands to a running ovs-vswitchd process. The currently supported commands are described below. The command descriptions assume an understanding of how to configure Open vSwitch.

  GENERAL COMMANDS

exit
    Causes ovs-vswitchd to gracefully terminate.

qos/show interface
    Queries the kernel for Quality of Service configuration and statistics associated with the given interface.

bfd/show [interface]
    Displays detailed information about Bidirectional Forwarding Detection configured on interface. If interface is not specified, then displays detailed information about all interfaces with BFD enabled.

bfd/set-forwarding [interface] status
    Force the fault status of the BFD module on interface (or all interfaces if none is given) to be status. status can be "true", "false", or "normal" which reverts to the standard behavior.

cfm/show [interface]
    Displays detailed information about Connectivity Fault Management configured on interface. If interface is not specified, then displays detailed information about all interfaces with CFM enabled.

cfm/set-fault [interface] status
    Force the fault status of the CFM module on interface (or all interfaces if none is given) to be status. status can be "true", "false", or "normal" which reverts to the standard behavior.

stp/tcn [bridge]
    Forces a topology change event on bridge if it's running STP. This may cause it to send Topology Change Notifications to its peers and flush its MAC table.. If no bridge is given, forces a topology change event on all bridges.

  BRIDGE COMMANDS
These commands manage bridges.

fdb/flush [bridge]
    Flushes bridge MAC address learning table, or all learning tables if no bridge is given.

fdb/show bridge
    Lists each MAC address/VLAN pair learned by the specified bridge, along with the port on which it was learned and the age of the entry, in seconds.

mdb/flush [bridge]
    Flushes bridge multicast snooping table, or all snooping tables if no bridge is given.

mdb/show bridge
    Lists each multicast group/VLAN pair learned by the specified bridge, along with the port on which it was learned and the age of the entry, in seconds.

bridge/reconnect [bridge]
    Makes bridge drop all of its OpenFlow controller connections and reconnect. If bridge is not specified, then all bridges drop their controller connections and reconnect.

    This command might be useful for debugging OpenFlow controller issues.

bridge/dump-flows bridge
    Lists all flows in bridge, including those normally hidden to commands such as ovs-ofctl dump-flows. Flows set up by mechanisms such as in-band control and fail-open are hidden from the controller since it is not allowed to modify or override them.

  BOND COMMANDS
These commands manage bonded ports on an Open vSwitch's bridges. To understand some of these commands, it is important to understand a detail of the bonding implementation called ``source load balancing'' (SLB). Instead of directly assigning Ethernet source addresses to slaves, the bonding implementation computes a function that maps an 48-bit Ethernet source addresses into an 8-bit value (a ``MAC hash'' value). All of the Ethernet addresses that map to a single 8-bit value are then assigned to a single slave.

bond/list
    Lists all of the bonds, and their slaves, on each bridge.

bond/show [port]
    Lists all of the bond-specific information (updelay, downdelay, time until the next rebalance) about the given bonded port, or all bonded ports if no port is given. Also lists information about each slave: whether it is enabled or disabled, the time to completion of an updelay or downdelay if one is in progress, whether it is the active slave, the hashes assigned to the slave. Any LACP information related to this bond may be found using the lacp/show command.

bond/migrate port hash slave
    Only valid for SLB bonds. Assigns a given MAC hash to a new slave. port specifies the bond port, hash the MAC hash to be migrated (as a decimal number between 0 and 255), and slave the new slave to be assigned.

    The reassignment is not permanent: rebalancing or fail-over will cause the MAC hash to be shifted to a new slave in the usual manner.

    A MAC hash cannot be migrated to a disabled slave.

bond/set-active-slave port slave
    Sets slave as the active slave on port. slave must currently be enabled.

    The setting is not permanent: a new active slave will be selected if slave becomes disabled.

bond/enable-slave port slave
    Enables (or disables) slave on the given bond port, skipping any updelay (or downdelay).

    This setting is not permanent: it persists only until the carrier status of slave changes.

bond/hash mac [vlan] [basis]
    Returns the hash value which would be used for mac with vlan and basis if specified.

lacp/show [port]
    Lists all of the LACP related information about the given port: active or passive, aggregation key, system id, and system priority. Also lists information about each slave: whether it is enabled or disabled, whether it is attached or detached, port id and priority, actor information, and partner information. If port is not specified, then displays detailed information about all interfaces with CFM enabled.

  DPCTL DATAPATH DEBUGGING COMMANDS
The primary way to configure ovs-vswitchd is through the Open vSwitch database, e.g. using ovs-vsctl(8). These commands provide a debugging interface for managing datapaths. They implement the same features (and syntax) as ovs-dpctl(8). Unlike ovs-dpctl(8), these commands work with datapaths that are integrated into ovs-vswitchd (e.g. the netdev datapath type).

dpctl/add-dp dp [netdev[,option]...]
    Creates datapath dp, with a local port also named dp. This will fail if a network device dp already exists.

    If netdevs are specified, ovs-vswitchd adds them to the new datapath, just as if add-if was specified.

dpctl/del-dp dp
    Deletes datapath dp. If dp is associated with any network devices, they are automatically removed.

dpctl/add-if dp netdev[,option]...
    Adds each netdev to the set of network devices datapath dp monitors, where dp is the name of an existing datapath, and netdev is the name of one of the host's network devices, e.g. eth0. Once a network device has been added to a datapath, the datapath has complete ownership of the network device's traffic and the network device appears silent to the rest of the system.

    A netdev may be followed by a comma-separated list of options. The following options are currently supported:

    type=type
        Specifies the type of port to add. The default type is system.

    port_no=port
        Requests a specific port number within the datapath. If this option is not specified then one will be automatically assigned.

    key=value
        Adds an arbitrary key-value option to the port's configuration.

    ovs-vswitchd.conf.db(5) documents the available port types and options.

dpctl/set-if dp port[,option]...
    Reconfigures each port in dp as specified. An option of the form key=value adds the specified key-value option to the port or overrides an existing key's value. An option of the form key=, that is, without a value, deletes the key-value named key. The type and port number of a port cannot be changed, so type and port_no are only allowed if they match the existing configuration.

dpctl/del-if dp netdev...
    Removes each netdev from the list of network devices datapath dp monitors.

dpctl/dump-dps
    Prints the name of each configured datapath on a separate line.

Prints a summary of configured datapaths, including their datapath
    numbers and a list of ports connected to each datapath. (The local port is identified as port 0.) If -s or --statistics is specified, then packet and byte counters are also printed for each port.

    The datapath numbers consists of flow stats and mega flow mask stats.

    The "lookups" row displays three stats related to flow lookup triggered by processing incoming packets in the datapath. "hit" displays number of packets matches existing flows. "missed" displays the number of packets not matching any existing flow and require user space processing. "lost" displays number of packets destined for user space process but subsequently dropped before reaching userspace. The sum of "hit" and "miss" equals to the total number of packets datapath processed.

    The "flows" row displays the number of flows in datapath.

    The "masks" row displays the mega flow mask stats. This row is omitted for datapath not implementing mega flow. "hit" displays the total number of masks visited for matching incoming packets. "total" displays number of masks in the datapath. "hit/pkt" displays the average number of masks visited per packet; the ratio between "hit" and total number of packets processed by the datapath".

    If one or more datapaths are specified, information on only those datapaths are displayed. Otherwise, ovs-vswitchd displays information about all configured datapaths.

  DATAPATH FLOW TABLE DEBUGGING COMMANDS
The following commands are primarily useful for debugging Open vSwitch. The flow table entries (both matches and actions) that they work with are not OpenFlow flow entries. Instead, they are different and considerably simpler flows maintained by the Open vSwitch kernel module. Use ovs-ofctl(8), instead, to work with OpenFlow flow entries.

The dp argument to each of these commands is optional when exactly one datapath exists, in which case that datapath is the default. When multiple datapaths exist, then a datapath name is required.

Prints to the console all flow entries in datapath dp's flow
    table. Without -m or --more, output omits match fields that a flow wildcards entirely; with -m or --more, output includes all wildcarded fields.

    If filter=filter is specified, only displays the flows that match the filter. filter is a flow in the form similiar to that accepted by ovs-ofctl(8)'s add-flow command. (This is not an OpenFlow flow: besides other differences, it never contains wildcards.) The filter is also useful to match wildcarded fields in the datapath flow. As an example, filter='tcp,tp_src=100' will match the datapath flow containing 'tcp(src=80/0xff00,dst=8080/0xff)'.

dpctl/add-flow [dp] flow actions

Adds or modifies a flow in dp's flow table that, when a packet
    matching flow arrives, causes actions to be executed.

    The add-flow command succeeds only if flow does not already exist in dp. Contrariwise, mod-flow without --may-create only modifies the actions for an existing flow. With --may-create, mod-flow will add a new flow or modify an existing one.

    If -s or --statistics is specified, then mod-flow prints the modified flow's statistics. A flow's statistics are the number of packets and bytes that have passed through the flow, the elapsed time since the flow last processed a packet (if ever), and (for TCP flows) the union of the TCP flags processed through the flow.

    With --clear, mod-flow zeros out the flow's statistics. The statistics printed if -s or --statistics is also specified are those from just before clearing the statistics.

Deletes the flow from dp's flow table that matches flow.
    If -s or --statistics is specified, then del-flow prints the deleted flow's statistics.

dpctl/get-flow [dp] ufid:ufid
    Fetches the flow from dp's flow table with unique identifier ufid. ufid must be specified as a string of 32 hexadecimal characters.

dpctl/del-flows [dp]
    Deletes all flow entries from datapath dp's flow table.

  CONNECTION TRACKING TABLE DEBUGGING COMMANDS
The following commands are primarily useful for debugging the connection tracking entries in the datapath.

The dp argument to each of these commands is optional when exactly one datapath exists, in which case that datapath is the default. When multiple datapaths exist, then a datapath name is required.

N.B.(Linux specific): the system datapaths (i.e. the Linux kernel module Open vSwitch datapaths) share a single connection tracking table (which is also used by other kernel subsystems, such as iptables, nftables and the regular host stack). Therefore, the following commands do not apply specifically to one datapath.

Prints to the console all the connection entries in the tracker used by
    dp. If zone=zone is specified, only shows the connections in zone. With --more, some implementation specific details are included. With --statistics timeouts and timestamps are added to the output.

dpctl/flush-conntrack [dp] [zone=zone]
    Flushes all the connection entries in the tracker used by dp. If zone=zone is specified, only flushes the connections in zone.

  DPIF-NETDEV COMMANDS
These commands are used to expose internal information (mostly statistics) about the ``dpif-netdev'' userspace datapath. If there is only one datapath (as is often the case, unless dpctl/ commands are used), the dp argument can be omitted.

dpif-netdev/pmd-stats-show [dp]
    Shows performance statistics for each pmd thread of the datapath dp. The special thread ``main'' sums up the statistics of every non pmd thread. The sum of ``emc hits'', ``masked hits'' and ``miss'' is the number of packets received by the datapath. Cycles are counted using the TSC or similar facilities (when available on the platform). To reset these counters use dpif-netdev/pmd-stats-clear. The duration of one cycle depends on the measuring infrastructure.

dpif-netdev/pmd-stats-clear [dp]
    Resets to zero the per pmd thread performance numbers shown by the dpif-netdev/pmd-stats-show command. It will NOT reset datapath or bridge statistics, only the values shown by the above command.

  DATAPATH DEBUGGING COMMANDS
These commands query and modify datapaths. They are are similar to ovs-dpctl(8) commands. dpif/show has the additional functionality, beyond dpctl/show of printing OpenFlow port numbers. The other commands are redundant and will be removed in a future release.

dpif/dump-dps
    Prints the name of each configured datapath on a separate line.

dpif/show
    Prints a summary of configured datapaths, including statistics and a list of connected ports. The port information includes the OpenFlow port number, datapath port number, and the type. (The local port is identified as OpenFlow port 65534.)

dpif/dump-flows [-m] dp
    Prints to the console all flow entries in datapath dp's flow table. Without -m, output omits match fields that a flow wildcards entirely; with -m output includes all wildcarded fields.

    This command is primarily useful for debugging Open vSwitch. The flow table entries that it displays are not OpenFlow flow entries. Instead, they are different and considerably simpler flows maintained by the datapath module. If you wish to see the OpenFlow flow entries, use ovs-ofctl dump-flows.

dpif/del-flows dp
    Deletes all flow entries from datapath dp's flow table and underlying datapath implementation (e.g., kernel datapath module).

    This command is primarily useful for debugging Open vSwitch. As discussed in dpif/dump-flows, these entries are not OpenFlow flow entries.

  OFPROTO COMMANDS
These commands manage the core OpenFlow switch implementation (called ofproto).

ofproto/list
    Lists the names of the running ofproto instances. These are the names that may be used on ofproto/trace.

ofproto/trace [dpname] odp_flow [-generate | packet]
    Traces the path of an imaginary packet through switch and reports the path that it took. The initial treatment of the packet varies based on the command:

    •   ofproto/trace looks the packet up in the OpenFlow flow table, as if the packet had arrived on an OpenFlow port.

    •   ofproto/trace-packet-out applies the specified OpenFlow actions, as if the packet, flow, and actions had been specified in an OpenFlow ``packet-out'' request.

    The packet's headers (e.g. source and destination) and metadata (e.g. input port), together called its ``flow,'' are usually all that matter for the purpose of tracing a packet. You can specify the flow in the following ways:

    dpname odp_flow
        odp_flow is a flow in the form printed by ovs-dpctl(8)'s dump-flows command. If all of your bridges have the same type, which is the common case, then you can omit dpname, but if you have bridges of different types (say, both ovs-netdev and ovs-system), then you need to specify a dpname to disambiguate.

    bridge br_flow
        br_flow is a flow in the form similar to that accepted by ovs-ofctl(8)'s add-flow command. (This is not an OpenFlow flow: besides other differences, it never contains wildcards.) bridge names of the bridge through which br_flow should be traced.

    Most commonly, one specifies only a flow, using one of the forms above, but sometimes one might need to specify an actual packet instead of just a flow:

    Side effects.
        Some actions have side effects. For example, the normal action can update the MAC learning table, and the learn action can change OpenFlow tables. The trace commands only perform side effects when a packet is specified. If you want side effects to take place, then you must supply a packet.

        (Output actions are obviously side effects too, but the trace commands never execute them, even when one specifies a packet.)

    Incomplete information.
        Most of the time, Open vSwitch can figure out everything about the path of a packet using just the flow, but in some special circumstances it needs to look at parts of the packet that are not included in the flow. When this is the case, and you do not supply a packet, then a trace command will tell you it needs a packet.

    If you wish to include a packet as part of a trace operation, there are two ways to do it:

    -generate
        This option, added to one of the ways to specify a flow already described, causes Open vSwitch to internally generate a packet with the flow described and then to use that packet. If your goal is to execute side effects, then -generate is the easiest way to do it, but -generate is not a good way to fill in incomplete information, because it generates packets based on only the flow information, which means that the packets really do not have any more information than the flow.

    packet
        This form supplies an explicit packet as a sequence of hex digits. An Ethernet frame is at least 14 bytes long, so there must be at least 28 hex digits. Obviously, it is inconvenient to type in the hex digits by hand, so the ovs-pcap(1) and ovs-tcpundump(1) utilities provide easier ways.

        With this form, packet headers are extracted directly from packet, so the odp_flow or br_flow should specify only metadata. The metadata can be:

        skb_priority
            Packet QoS priority.

        pkt_mark
            Mark of the packet.

        ct_state
            Connection state of the packet.

        ct_zone
            Connection tracking zone for packet.

        ct_mark
            Connection mark of the packet.

        ct_label
            Connection label of the packet.

        tun_id
            The tunnel ID on which the packet arrived.

        in_port
            The port on which the packet arrived.

    The in_port value is kernel datapath port number for the first format and OpenFlow port number for the second format. The numbering of these two types of port usually differs and there is no relationship.

    ofproto-trace-packet-out accepts an additional -consistent option. With this option specified, the command rejects actions that are inconsistent with the specified packet. (An example of an inconsistency is attempting to strip the VLAN tag from a packet that does not have a VLAN tag.) Open vSwitch ignores most forms of inconsistency in OpenFlow 1.0 and rejects inconsistencies in later versions of OpenFlow. The option is necessary because the command does not ordinarily imply a particular OpenFlow version. One exception is that, when actions includes an action that only OpenFlow 1.1 and later supports (such as push_vlan), -consistent is automatically enabled.

ofproto/self-check [switch]
    Runs an internal consistency check on switch, if specified, otherwise on all ofproto instances, and responds with a brief summary of the results. If the summary reports any errors, then the Open vSwitch logs should contain more detailed information. Please pass along errors reported by this command to the Open vSwitch developers as bugs.

  VLOG COMMANDS
These commands manage ovs-vswitchd's logging settings.

vlog/set [spec]
    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.

        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 ovs-vswitchd was invoked with the --log-file option.

    For compatibility with older versions of OVS, any is accepted as a word but has no effect.

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

vlog/list
    Lists the supported logging modules and their current levels.

vlog/list-pattern
    Lists logging patterns used for each destination.

vlog/reopen
    Causes ovs-vswitchd to close and reopen its log file. (This is useful after rotating log files, to cause a new log file to be used.)

    This has no effect unless ovs-vswitchd was invoked with the --log-file option.

vlog/disable-rate-limit [module]...
    By default, ovs-vswitchd limits the rate at which certain messages can be logged. When a message would appear more frequently than the limit, it is suppressed. This saves disk space, makes logs easier to read, and speeds up execution, but occasionally troubleshooting requires more detail. Therefore, vlog/disable-rate-limit allows rate limits to be disabled at the level of an individual log module. Specify one or more module names, as displayed by the vlog/list command. Specifying either no module names at all or the keyword any disables rate limits for every log module.

    The vlog/enable-rate-limit command, whose syntax is the same as vlog/disable-rate-limit, can be used to re-enable a rate limit that was previously disabled.

  MEMORY COMMANDS
These commands report memory usage.

memory/show
    Displays some basic statistics about ovs-vswitchd's memory usage. ovs-vswitchd also logs this information soon after startup and periodically as its memory consumption grows.

  COVERAGE COMMANDS
These commands manage ovs-vswitchd's ``coverage counters,'' which count the number of times particular events occur during a daemon's runtime. In addition to these commands, ovs-vswitchd automatically logs coverage counter values, at INFO level, when it detects that the daemon's main loop takes unusually long to run.

Coverage counters are useful mainly for performance analysis and debugging.

coverage/show
    Displays the averaged per-second rates for the last few seconds, the last minute and the last hour, and the total counts of all of the coverage counters.

  OPENVSWITCH TUNNELING COMMANDS
These commands query and modify OVS tunnel components. Ref to README-native-tunneling.md for more info.

ovs/route/add ipv4_address/plen output_bridge [GW]
    Adds ipv4_address/plen route to vswitchd routing table. output_bridge needs to be OVS bridge name. This command is useful if OVS cached routes does not look right.

ovs/route/show
    Print all routes in OVS routing table, This includes routes cached from system routing table and user configured routes.

ovs/route/del ipv4_address/plen
    Delete ipv4_address/plen route from OVS routing table.

tnl/neigh/show

tnl/arp/show
    OVS builds ARP cache by snooping are messages. This command shows ARP cache table.

tnl/neigh/set bridge ip mac

tnl/arp/set bridge ip mac
    Adds or modifies an ARP cache entry in bridge, mapping ip to mac.

tnl/neigh/flush

tnl/arp/flush
    Flush ARP table.

tnl/egress_port_range [num1] [num2]
    Set range for UDP source port used for UDP based Tunnels. For example VxLAN. If case of zero arguments this command prints current range in use.

OPENFLOW IMPLEMENTATION

This section documents aspects of OpenFlow for which the OpenFlow specification requires documentation.

  Packet buffering.
The OpenFlow specification, version 1.2, says:

    Switches that implement buffering are expected to expose, through documentation, both the amount of available buffering, and the length of time before buffers may be reused.

Open vSwitch maintains a separate set of 256 packet buffers for each OpenFlow connection. Any given packet buffer is preserved until it is referenced by an OFPT_FLOW_MOD or OFPT_PACKET_OUT request or for 5 seconds, whichever comes first.

LIMITS

We believe these limits to be accurate as of this writing. These limits assume the use of the Linux kernel datapath.

•   ovs-vswitchd started through ovs-ctl(8) provides a limit of 65535 file descriptors. The limits on the number of bridges and ports is decided by the availability of file descriptors. With the Linux kernel datapath, creation of a single bridge consumes three file descriptors and adding a port consumes "n-handler-threads" file descriptors per bridge port. Performance will degrade beyond 1,024 ports per bridge due to fixed hash table sizing. Other platforms may have different limitations.

•   2,048 MAC learning entries per bridge, by default. (This is configurable via other-config:mac-table-size in the Bridge table. See ovs-vswitchd.conf.db(5) for details.)

•   Kernel flows are limited only by memory available to the kernel. Performance will degrade beyond 1,048,576 kernel flows per bridge with a 32-bit kernel, beyond 262,144 with a 64-bit kernel. (ovs-vswitchd should never install anywhere near that many flows.)

•   OpenFlow flows are limited only by available memory. Performance is linear in the number of unique wildcard patterns. That is, an OpenFlow table that contains many flows that all match on the same fields in the same way has a constant-time lookup, but a table that contains many flows that match on different fields requires lookup time linear in the number of flows.

•   255 ports per bridge participating in 802.1D Spanning Tree Protocol.

•   32 mirrors per bridge.

•   15 bytes for the name of a port. (This is a Linux kernel limitation.)

SEE ALSO
ovs-appctl(8), ovsdb-server(1), INSTALL.Linux in the Open vSwitch distribution.