Table of Contents
- Build & Install
- Building from GIT
pimd is a lightweight, stand-alone PIM-SM/SSM multicast routing daemon available under the free 3-clause BSD license. This is the restored original version from University of Southern California, by Ahmed Helmy, Rusty Eddy and Pavlin Ivanov Radoslavov.
pimd is primarily developed on Linux and should work as-is out of the
box on all major distributions. Other UNIX variants (OpenBSD, NetBSD,
and FreeBSD) should also work, but are not as thoroughly tested. For
some tips and details, see the
For a summary of changes for each release, see the ChangeLog.
Build & Install
When building pimd from source you first need to run the
script to generate the file
config.mk. The script relies on Bourne
shell standard features as well as expr and uname. Any optional pimd
features, such as
--enable-scoped-acls are activated here as well.
./configure --enable-scoped-acls && make sudo make install
The configure script and Makefile supports de facto standard settings
and environment variables such as
DESTDIR= for the
install process. E.g., to install pimd to
/usr instead of the default
/usr/local, but redirect to a binary package directory in
./configure --prefix=/usr && make clean all make VERSION=2.3.0-1 DESTDIR=/tmp/pimd-2.3.0-1 install
Building from GIT
If you want to contribute, or simply just try out the latest but unreleased features, then you need to know a few things about the GNU build system:
configure.acand a per-directory
Makefile.amare key files
Makefile.inare generated from
Makefileis generated by
To build from GIT you first need to clone the repository and run the
autogen.sh script. This requires
autoconf to be
installed on your system.
git clone https://github.com/troglobit/pimd.git cd pimd/ ./autogen.sh ./configure && make
GIT sources are a moving target and are not recommended for production systems, unless you know what you are doing!
The configuration is kept in the file
/etc/pimd.conf, the order of
the statements are in some cases important.
PIM-SM is a designed to be a protocol independent multicast routing protocol. As such it relies on unicast protocols like, e.g, OSPF, RIP, or static routing entries, to figure out the path to all multicast capable neighboring routers. This information is necessary in setups with more than one route between a multicast sender and a receiver to figure out which PIM router should be the active forwarder.
However, pimd currently cannot retrieve the unicast routing distance (preference) and metric of routes from the system, not from the kernel nor a route manager like zebra. Hence, pimd currently needs to be setup statically on each router using the desired distance and metric for each active interface. If either the distance and/or the metric is missing in an interface configuration, the following two defaults will be used:
default-route-distance <1-255> default: 101 default-route-metric <1-1024> default: 1024
By default pimd starts up on all interfaces it can find, using the above defaults. To configure individual interfaces use:
phyint <address | ifname> ...
You can reference the interface via either its local IPv4 address or its name, e.g., eth0. Some common interface settings are:
disable: Disable pimd on this interface, i.e., do not send or listen for PIM-SM traffic
dr-priority <1-4294967294>: The DR Priority option, sent in all all PIM Hello messages. Used instead of the IP address in all DR elections, if all PIM routers in LAN advertise it. The higher, the better, default 1.
distance <1-255>: The interface's admin distance value (also confusingly referred to as metric preference in the RFC) in PIM Assert messages. Used with
metricto elect the active multicast forwarding router. Defaults to
metric <1-1024>: The cost for traversing this router. Used with the
preferencevalue above. Defaults to
More interface settings are available, see the pimd(8) manual page for the full details.
The most notable feature of PIM-SM is that multicast is distributed from
so called Rendezvous Points (RP). Each RP handles distribution of one
or more multicast groups, pimd can be configured to advertise itself as
a candidate RP
rp-candidate, and request to be static RP
for one or more multicast groups.
rp-address <address> [<group>[/<LENGTH> | masklen <LENGTH]
rp-address setting is the same as the Cisco
ip pim rp-address
setting to configure static Rendezvous Points. The first argument can
be an IPv4 address or a multicast group address. The default group and
prefix length is 126.96.36.199/16. Static RP's always have priority 1.
rp-candidate [address | ifname] [time <10-16383>] [priority <0-255>]
The Rendezvous Point candidate, or CRP, setting is the same as the Cisco
ip pim rp-candidate setting. Use it to control which interface that
should be used in RP elections.
address | ifname: Optional local IPv4 address, or interface name to acquire address from. The default is to use the highest active IP address.
time <10-16383>: The interval, in seconds, between advertising this CRP. Default: 60 seconds
priority <0-255>: How important this CRP is compared to others. The lower the value here, the more important the CRP. Like Cisco, pimd defaults to priority 0 when this is left out
In the CRP messages sent out by pimd, one or more multicast groups can be advertised using the following syntax.
group-prefix <group>[</LENGTH> | masklen <LENGTH>]
group-prefix setting defines one multicast group and an optional
mask length, which defaults to 16 if left out. A maximum of 255
multicast group prefix records is possible for the CRP.
To keep track of all Rendezvous Points in a PIM-SM domain there exists a feature called Bootstrap Router. The elected BSR in a PIM-SM domain periodically announces the RP set in Bootstrap messages. For details on PIM BSR operation, see RFC 5059.
bsr-candidate [address | ifname] [priority <0-255>]
The configuration of a Candidate BootStrap Router (CBSR) is very similar
to that of CRP, except for the interval time. If either the address or
the interface name is left out pimd uses the highest active IP address.
If the priority is left out,
pimd (like Cisco) defaults to priority 0.
To disable CRP and CBSR completely in
pimd, simply comment the two
lines out from your
pimd.conf, and make sure
pimd can find the file.
pimd cannot find the file it will default to them enabled,
with defaults listed in the
pimd.conf included in the distribution.
In a PIM-SM domain there can be two, or more, paths from a designated router (DR) for a multicast sender to reach a receiver. When receivers begin joining multicast groups all data is received via the shared tree (RPT) from each Rendezvous Point (RP). This is often not an optimal route, so when the volume starts exceeding a configurable threshold, on either the last-hop router or the RP itself, the router will attempt to switch to the shortest path tree (SPT) from the multicast source to the receiver.
In versions of pimd prior to 2.2.0 this threshold was confusingly split in two different settings, one for the DR and one for the RP. These settings are still supported, for compatibility reasons and documented in the man-page, but it is strongly recommended to change to the new syntax instead:
spt-threshold [rate <KBPS> | packets <NUM> | infinity] [interval <5-60>]
Only slightly different from the Cisco
ip pim spt-threshold setting,
pimd can trigger a switch to SPT on a rate or number of packets and you
can also tweak the poll interval. It's recommended to keep the interval
in the tens of seconds, the default is 100 sec. The default threshold
is set to zero packets, which will cause a switch over to the SPT after
the first multicast packet is received.
# Interface eth0 is disabled, i.e., pimd will not run there. phyint eth0 disable # On this LAN we have a lower numeric IP than other PIM routers # but we want to take care of forwarding all PIM messages. phyint eth1 dr-priority 10 # Partake in BSR elections on eth1 bsr-candidate eth1 # Offer to be an RP for all of 188.8.131.52/4 rp-candidate eth1 group-prefix 184.108.40.206 masklen 4 # This is the built-in defaults, switch to SPT on first packet spt-threshold packets 0 interval 100
Having set up the configuration file, you are ready to run pimd. As usual, it is recommended that you start it manually first, to make sure everything works as expected, before adding it to your system's startup scripts, with any startup flags it might need.
pimd [-c file] [-d subsys1[,...,subsysN]] [-s level]
-c file: Utilize the specified configuration file rather than the default,
-d [subsys1,...,subsysN]: Subsystems to enable debug for when running the daemon. Optional argument, if left out, all subsystems are enabled. Type
pimd -hfor a full list of subsystems
-s level: Log level, one of
debug. Default is
pimd -c /cfg/pimd.conf -digmp_proto,pim_jp,kernel,pim_register
Notice the lack of spaces in the option argument to
To see the virtual interface table, including neighboring PIM routers, and the multicast routing table:
or to watch it continually:
watch pimd -r
In addition, pimd logs important events to the system logfile, in
particular at startup when parsing the
pimd.conf configuration file.
git clone https://github.com/troglobit/pimd cd pimd
See the file CONTRIBUTING.md for further details.