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mrouted

README for mrouted, the DVMRP Multicast Routing Daemon
======================================================
mrouted is an implementation of the DVMRP multicast routing protocol. It turns
a UNIX workstation into a DVMRP multicast router with tunnel support, in order
to cross non-multicast-aware routers.

DVMRP is a distance vector based protocol, derived from RIP, suitable for
closely located multicast users in smaller networks.  It simply floods all
multicast streams to all routers, i.e. implicit join.  This is also known as
"flood and prune" since you can opt out from groups you do not want. For a
detailed explanation of the protocol, consult RFC 1075.

History
-------
The mrouted routing daemon was developed by Steve Deering, Ajit Thyagarajan,
Bill Fenner, David Thaler and Daniel Zappala.  With contributions by many
others.

The last release by Mr. Fenner was 3.9-beta3 on April 26 1999 and mrouted has
been in "beta" status since then.  Several prominent UNIX operating systems,
such as AIX, Solaris, HP-UX, BSD/OS, NetBSD, FreeBSD, OpenBSD as well as most
GNU/Linux based distributions have used that beta as a de facto stable release,
with (mostly) minor patches for system adaptations.  Over time however many
dropped support, but Debian and OpenBSD kept it under their wings.

In March 2003 OpenBSD, led by the fearless Theo de Raadt, managed to convince
Stanford to release mrouted under a fully free license, the BSD license[1].
Nevertheless, in February 2005 Debian finally dropped[2] mrouted as an
"obsolete protocol".

For a long time the OpenBSD team remained the sole guardian of this project.

In 2010 this effort of bringing mrouted back to life was started.  The 3.9.x
stable series represent the first releases in over a decade.  Patches from all
over the Internet, including OpenBSD, have been integrated.

Bugs
----
The basic functionality has been tested thoroughly over the years, but that
does not mean mrouted is bug free.  Please report any oddities, feature
requests, patches or pull requests in the github issue tracker at:

	http://github.com/troglobit/mrouted/issues

Mrouted contain "hacks" to recognize Cisco IOS's pseudo-DVMRP implementation to
yield all "DVMRP" versions of 10 and higher to IOS.  Previous pre-release
versions of mrouted 3.9.0 made the assumption that the IOS bug that causes it
to use the IOS version number instead of the DVMRP version number would be
fixed by the time 12.0 was out.

Configuring
-----------

By default mrouted reads its configuration file from /etc/mrouted.conf.  You can
override the default by specifying an alternate file when invoking mrouted.

	mrouted -f /path/file.conf

The mrouted daemon can reconfigure itself at runtime if you change the configuration
file, simply send the process a SIGHUP to activate new changes to the file.  The PID
is saved automatically to the file /var/run/mrouted.pid at start.

By default, mrouted configures itself to act as a multicast router on all multicast
capable interfaces, excluding the loopback interface that has the IFF_MULTICAST flag
set.  Therefore, you do not need to explicitly configure mrouted, unless you need to
setup tunnel links, change the default operating parameters, or disable multicast
routing over a specific physical interface.

See the man page for further details.

Running
-------
The mrouted daemon must run as root.

For the native mrouted tunnel to work in Linux based systes you need to have
the "ipip" kernel module loaded or as built-in.

	modprobe ipip

Several signals are supported, for querying status, or simply for reloading the
configuration.  See the man page for details.

MROUTED 3.8
===========
Mrouted 3.8 has two optional features: SNMP and RSRR.  RSRR support is
required for running RSVP; the SNMP code, with the help of the ISODE snmpd,
implements both the Multicast MIB and the DVMRP MIB.

RSRR
----
Routing Support for Resource Reservations (RSRR) was contributed by
Daniel Zappala <daniel@isi.edu>.

Note: This has not been tested in many years ...

To enable RSRR support, uncomment the three lines starting with RSRR near
the top of the Makefile and "make clean; make".  Or use the prebuilt binary,
mrouted.rsrr .

RSRR allows RSVP to query mrouted for its routing entry for a particular
source-group pair.  Using the routing entry and the IP_MULTICAST_VIF socket
call, RSVP can forward distinct control messages out each outgoing
interface.  This version of mrouted supports RSRR messages using a Unix
datagram socket.

RSRR currently includes two pairs of query-reply messages.  RSVP sends an
Initial Query when it starts.  Mrouted responds with an Initial Reply that
includes the set of vifs it is using, flagging those that are
administratively disabled.  When RSVP needs the routing entry for a
source-group pair, it sends a Route Query.  Mrouted responds with a Route
Reply that includes the incoming vif and outgoing vifs for the source-group
pair.

RSVP may request route change notification by setting the notification bit
in the Route Query.  If mrouted can provide route change notification for
the source-group pair, it sets the notification bit in its Route Reply.
When the routing entry for the source-group pair changes, mrouted sends an
unsolicited Route Reply containing the new routing information.  The initial
release of mrouted 3.5 did not support route change notification and always
returned a Route Reply with the notification bit cleared.  This release of
mrouted provides route change notification when possible.

SNMP
----
SNMP support was contributed by David Thaler <thalerd@eecs.umich.edu>.
Note: This has not been tested in many years ...

To enable SNMP support, uncomment the six lines near the top of the Makefile
below the description of SNMP support.

To link the SNMP-capable mrouted, you need the CMU libraries.  See
http://nic.merit.edu/~mbone/ for a full mrouted-snmp distribution.

Make sure to add the "sysName", "sysContact", "sysVersion" and "sysLocation"
variables to your /etc/mrouted.conf if you want them to provide anything
other than default values.

Example:

sysName	"tibia"
sysContact "Bill Fenner <fenner@parc.xerox.com> +1 415 812-4816"
sysVersion "SunOS 4.1.3 and mrouted 3.8"
sysLocation "MAXC room, PARC building 35"

The SNMP version of mrouted has an additional command line flag:

  -P snmp_port

     Specifies a port for SNMP communication (default 161).  This option
     should be used when another SNMP daemon already exists.  The preferred
     alternate port in this case is port 9161.

The mstat(8) program allows querying of statistics using SNMP.

Footnotes
---------
[1] - http://www.openbsd.org/cgi-bin/cvsweb/src/usr.sbin/mrouted/LICENSE
[2] - http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=288112