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]:6632. 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]:6632.
- 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:6632:[::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:6632:[::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.
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
- Causes ovs-vswitchd to detach itself from the foreground session
and run as a background process. ovs-vswitchd detaches only after
it has connected to the database, retrieved the initial configuration, and
set up that configuration.
- --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.
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
-
- --private-key=privkey.pem
- Specifies a PEM file containing the private key used as
ovs-vswitchd's identity for outgoing SSL connections.
- -c cert.pem
-
- --certificate=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
-
- --ca-cert=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
-
- --ca-cert=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.
- -v[spec]
-
- --verbose=[spec]
- Sets logging levels. Without any spec, sets the log level for every
module and facility 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 --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
-
- --verbose
- Sets the maximum logging verbosity level, equivalent to
--verbose=dbg.
- -vPATTERN:facility:pattern
-
- --verbose=PATTERN:facility:pattern
- Sets the log pattern for facility to pattern. Refer to
ovs-appctl(8) for a description of the valid syntax for
pattern.
- --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.
- -h
-
- --help
- Prints a brief help message to the console.
- -V
-
- --version
- 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.
- 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
-
- bond/disable-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.
DATAPATH COMMANDS¶
These commands manage logical datapaths. They are are similar to the equivalent
ovs-dpctl commands.
- 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]
-
- ofproto/trace bridge br_flow [-generate |
packet]
-
- ofproto/trace-packet-out [-consistent] [dpname]
odp_flow [ -generate | packet] actions
-
- ofproto/trace-packet-out [-consistent] bridge
br_flow [ -generate | packet] actions
- 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.
- 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 facility 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:facility:pattern
- Sets the log pattern for facility 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/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]...
-
- vlog/enable-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.
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
7500 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 3 file descriptors and
adding a port consumes 1 file descriptor. 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.