Static Multicast Routing Daemon

- 2 mins read

SMCRoute is a daemon and command line tool to manipulate the multicast routing table in the UNIX kernel. Both FreeBSD and Linux kernels are supported, but it may work on other systems as well.

SMCRoute can be used as an alternative to dynamic multicast routing daemons like mrouted or pimd when (only) static multicast routes should be maintained or no proper signalling exists.

The full documentation of SMCRoute is available in the manual pages, see smcrouted(8), smcroutectl(8), and smcroute.conf(5).

Problems? See the Multicast HowTo for help!

Features

  • Full IPv4 and IPv6 support
  • Configuration file support, /etc/smcroute.conf
  • Configuration include support, /etc/smcroute.d/*.conf
  • Support for restarting and reloading the .conf on SIGHUP
  • Support for seamless reload and update on SIGHUP, i.e., established multicast flows are not disturbed by reloading the configuration or adding/removing outbound interfaces to existing routes
  • Source-less on-demand routing, a.k.a. (*,G) based static routing
  • Support for ranges, (S/LEN,G) and/or (S,G/LEN), or (S/LEN,G/LEN), be careful though since this expands to multiple kernel routes
  • Source specific group join support
  • Optional built-in mrdisc support, RFC4286 (IPv4 only)
  • Support for multiple routing tables on Linux
  • Client with built-in support to show routes and joined groups
  • Interface wildcard matching, eth+ matches eth0, eth15

Why a Daemon?

One common question is why SMCRoute must be a daemon, why not just a simple tool, like ip route for unicast routes? The answer is that to be able to add multicast routes a program must connect to the multicast routing socket in the kernel, when that socket is closed, which is done automatically when a UNIX program ends, the kernel cleans up all routes.

Origin & References

SMCRoute was originally written by Carsten Schill. Later on Julien Blache, Todd Hayton and Micha Lenk picked up development for Debian.

Since 2011 Joachim Wiberg heads development at GitHub. New features include config file support, reloading config on SIGHUP, source-less on-demand (*,G) routing, TTL scoping and support for disabling ALL interfaces except the few used for multicast routing.

Issue tracker and GIT repository available at GitHub.

See also the OpenHub page, the Freshcode page, or the now dormant Free(code) page.