pimd(8) PIM-SM/SSM v2 dynamic multicast routing daemon


pimd [-fhlNqr ] [-c FILE ] [-d [SYS[,SYS,...] ] [-s LEVEL ]


pimd is a lightweight, stand-alone PIM-SM/SSM v2 multicast routing daemon available under the free 3-clause BSD license. This is the restored original from University of Southern California, by Ahmed Helmy, Rusty Eddy and Pavlin Ivanov Radoslavov.

Protocol Independent Multicast - Sparse Mode (PIM-SM):

  • maintains the traditional IP multicast service model of receiver-initiated membership;
  • uses explicit joins that propagate hop-by-hop from members' directly connected routers toward the distribution tree.
  • builds a shared multicast distribution tree centered at a Rendezvous Point (RP), and then builds source-specific trees for those sources whose data traffic warrants it.
  • is not dependent on a specific unicast routing protocol; and
  • uses soft-state mechanisms to adapt to underlying network conditions and group dynamics.

The robustness, flexibility, and scaling properties of this architecture make it well suited to large heterogeneous internetworks.

pimd originally only implemented RFC2362, but since v2.3.0 is supporting more and more of RFC4601.


This program follows the usual UNIX command line syntax, with long options starting with two dashes (`-'). The options are as follows:

-h, -help
Print a help message and exit.
-c, -config=FILE
Specify an alternative configuration file, default /etc/pimd.conf If pimd cannot find its configuration file it will start up with fallback defaults, which include enabling both bsr-candidate and rp-candidate
-d, -debug[=SYS[,SYS...]
By default, pimd daemonizes itself by detaching from the invoking terminal and forking to the background. However, if -d, -debug or -f, -foreground is specified, pimd runs in the foreground of the starting terminal. If -d is given without any argument pimd defaults to debug all subystems.

Available subsystems are:

Debug inbound/outbout packets
Pruning operations, or pruned routes
Routing messages
Detailed routing information
Neighbor gossip
Debug routing cache
Debug timeouts
Show interface (VIF) debug messages
Debug group memberships
Multicast traceroute information
Debug IGMP messages
Debug ICMP messages
Debug RSRR messages
All PIM messages
PIM routing messages
PIM bootstrap router messages
Detailed PIM debug
Debug hello messages to/from neighbors

-f, -foreground
Run in the foreground, do not detach from calling terminal and do not fork to background. Useful not only when debugging (above) but also when running under a process monitor like daemontools, runit, finit, or systemd.
-l, -reload-config
Tell a running pimd to reload its configuration. This is done by sending a SIGHUP to the PID listed in /var/run/pimd.pid Depending on the capabilities of your user, you may need to be root to do this.
-N, -disable-vifs
This prevents pimd from being activated on all interfaces by default. When this command line option is given, use `phyint IFNAME enable` to selectively activate PIM services on an interface.
-q, -quit-daemon
Tell a running pimd to quit. Similar to -l, -reload-config but this command sends SIGTERM. Depending on the capabilities of your user, you may need to be root to do this.
-r, -show-routes
Show state of VIFs and multicast routing tables. This is command sends SIGUSR1 to a running , similar to -l -reload-config. Depending on the capabilities of your user, you may need to be root to do this.
-v, -version
Show pimd version
-s, -loglevel=LEVEL
Set log level to one of the following, default notice

Disable all logging
Error conditions
Warning conditions
Normal but significant condition (Default)
Debug-level messages


The configuration is kept in the file /etc/pimd.conf The file format is relatively free-form: whitespace (including newlines) is not significant. However, the order of some statements are important, see more below.

All <masklen> arguments to an IPv4 address, group or network can also be given in the alternative /CIDR format. E.g., <group>/<masklen>.

Here are the different configuration settings:

<address | ifname>

[disable | enable ] [igmpv2 | igmpv3 ]
[dr-priority <1-4294967294> ]
[ttl-threshold <1-255> ] [distance <1-255> ] [metric <1-1024> ]
[altnet <network> [/<masklen> | masklen <masklen> ] ]
[scoped <network> [/<masklen> | masklen <masklen> ] ]

[address | ifname ] [priority <number> ]
[address | ifname ] [priority <0-255> ] [time <10-16384> ]

group-prefix <group>[/<masklen> | masklen <masklen>]

group-prefix ...

rp-address <address> [<group-addr>[/<masklen> | masklen <masklen]
[rate <KBPS> | packets <NUM> | infinity ] [interval <SEC> ]

By default, pimd will be activated on all multicast capable interfaces. The phyint setting and the -N, -disable-vifs command line option control this behaviour. More on the phyint interface configuration setting below.

The default-route-distance option has nothing to do with the system default route, it is rather the default value for the unicast routing protocol's administrative distance. It is used in PIM Assert elections to determine upstream routers. Currently pimd cannot obtain the admin distance and metric from the unicast routing protocols, so a default routing protocol distance (the RFC confusingly refers to this as metric prefererence may be configured. In a PIM Assert election, the router advertising the lowest assert preference will be selected as the forwarder and upstream router for the LAN. Setting 101 should be sufficiently high so that asserts from Cisco or GateD routers are preferred over poor-little pimd.

It is reccommended that distances be set such that metrics are never consulted. However, default routing metrics may also be set using the default-route-metric option. (Again, this has nothing to do with the system default route.) This item sets the cost for sending data through this router. You want only PIM-SM data to go to this daemon; so once again, a high value is recommended to prevent accidental usage. The preferred default value is 1024. Both defaults can be overridden per phyint, so learned routes, or PIM Asserts use the phyint's values.

Please also note that PIM Assert elections are not the same as the DR election. The PIM Assert election determines the active multicast forwarder, whereas the DR election determines the active PIM router.

Two settings for IGMP behavior are available: igmp-query-interval and igmp-querier-timeout which are similar, but very different. The former controls the interval between IGMP querys when elected as querier, the latter controls the timeout for the elected querier -- before pimd decides to take over. In IGMP the lowest numerical address in a LAN becomes the elected querier. Obviously these settings must be handled with care. The RFC recommends that the querier timeout is set to a robustness value times the query interval, plus have the query response time. The pimd robustness value for IGMP is 3 and the default query response time is 10 sec. Since pimd v2.3.0 the default query interval is 12 sec, which makes the querier timeut default to 41 sec, but this is rounded off to 42 to honor the late Douglas Adams.

The PIM Hello message interval can be tuned by changing the hello-interval setting. Changing this value also affects the hold-time value included in Hello messages. The hold-time value is 3.5 times hello-interval. The default value for the Hello interval is 30 sec. Anything less than 30 sec is considered an "aggressive" setting and is unsupported.

The phyint option refers to a physical interface and must come after default-route-metric and default-route-distance Select the interface either by its IP address or interface name ifname (e.g. eth0). If you just want to activate this interface with default values, you don't need to put anything else on the line. However, there are some additional settings:

  • disable Do not send PIM-SM traffic through this interface nor listen for PIM-SM traffic from this interface. Default: enable. enable Selectively enable which interfaces to send PIM-SM traffic through. Useful with the -N command line option.
  • igmpv2 Force interface to use IGMPv2, or
  • igmpv3 Use IGMPv3, this is the default since v2.3.0.
  • dr-priority <1-4294967294> When there are multiple PIM routers on the same LAN the DR is usually elected based on the highest numerical IP address. This setting can be used to control the DR Priority option in PIM Hellow messages, which by default otherwise is 1. When the DR Priority option is advertised by all PIM routers on the same LAN the highest priority router wins the DR election, regardless of its IP. If any router does not advertise the DR Priority option, or the same priority is advertised by more than one router, the protocol falls back to using the IP address.
  • ttl-threshold <1-255> The TTL threshold for multicast frames to be forwarded from this interface. Default: 1
  • distance <1-255> Use this to override the default-route-distance (101) on this phyint in PIM Assert elections.
  • metric <1-1024> The cost of sending data through this interface. Defaults to default-route-metric (1024) if not assigned.
  • altnet <network/len> Alternative host(s)/network(s) to accept as locally attached multicast sources on a given interface. If a phyint is attached to multiple IP subnets, describe each additional subnet with the altnet keyword.
  • scoped <network/len> Optional scoping of multicast groups. This allows interfaces to be configured as an administrative boundary for the specified group(s). Multicast streams belonging to the scoped groups will not be forwarded.

Add one phyint line per interface on this router. If you don't do this, pimd will either be completely silent (if you provide the -N command line option), or simply assume that you want it to utilize all interfaces using default settings.

Both the bsr-candidate (CBSR) and rp-candidate (CRP) settings are enabled in the default configuration. Disabling them, by commenting them out in the config file, for all PIM capable routers is a bad idea. When troubleshooting, ensure at least one bootstrap router (BSR) and at least one rendez-vous point (RP) in PIM-SM, is available. Both settings share the following options, with priority being interpreted differently:

  • address | ifname Optional local IPv4 address, or interface name to acquire address from. If both address and ifname is left out, pimd will default to the highest active IP address.
  • priority <0-255> How important this router is compared to others. For CRP, the lower the value the more important the router is considered. For BSR it is of course the exact opposite: a higher value is preferred. If the priority is left out pimd and Cisco IOS defaults to 0 for both, but the standard says 192 for RP.
  • time <10-16383> The number of seconds to wait between advertising this CRP. The default value is 30 seconds. Use a lower value for faster convergence.

group-prefix sub-setting to rp-candidate is the set of multicast groups that the CRP will advertise to other routers, if it wins an election:

  • group A specific multicast group or network range this router will handle.
  • masklen Optional number of groups, in prefix length format. Remember that a multicast address is a Class D and has a netmask of, which means its length is 4.

Multiple lines of group-prefix may be given, but max number of records supported in pimd is 255.

The rp-address setting is for static rendezvous point (RP) configurations. It defines the RP for a given group, or range or groups. The argument can be either a unicast address or a multicast group, with an optional group address and netmask. Default group and netmask is Note: all static RP's are announced with priority 1.

The spt-threshold setting replaces two older configuration settings, switch_data_threshold and switch_register_threshold It controls the switch-over from the shared tree to the shortest-path source tree. The default is to do the switch-over after the first packet, but only after 100 seconds. If infinity is specified the shortest path switch-over is disabled.


pimd responds to the following signals:

Restarts . The configuration file is reread every time this signal is evoked.
Terminates execution gracefully (i.e. by sending good-bye messages to all neighboring routers).
The same as TERM.
Dumps the internal state of VIFs and multicast routing tables to /var/run/pimd/pimd.dump See also the -r, -show-routes option above.

For convenience in sending signals, pimd writes its process ID to /var/run/pimd.pid upon startup.




pimd was written by Ahmed Helmy, George Edmond "Rusty" Eddy, and Pavlin Ivanov Radoslavov. PIM-SSM, including full IGMPv3 support, added by Markus Veranen. With contributions by many others.

This manual page was initially written by Antonín Král for the Debian GNU/Linux system, and then updated by Joachim Nilsson for the GitHub pimd project.