mrouted.1m (2010 09)

m
mrouted(1M) mrouted(1M)
NAME
mrouted - IP multicast routing daemon
SYNOPSIS
/usr/sbin/mrouted
[-p][-c config_file ][
-d debug_level ]
DESCRIPTION
The
mrouted command is an implementation of the Distance-Vector Multicast Routing Protocol
(DVMRP), an earlier version of which is specified in RFC 1075. It maintains topological knowledge via a
distance-vector routing protocol (like RIP, described in RFC 1058), upon which it implements a multicast
datagram-forwarding algorithm called Reverse Path Multicasting.
mrouted forwards a multicast datagram along a shortest (reverse) path tree rooted at the subnet on
which the datagram originates. The multicast delivery tree may be thought of as a broadcast delivery
tree that has been pruned back so that it does not extend beyond those subnetworks that have members
of the destination group. Hence, datagrams are not forwarded along those branches which have no
listeners of the multicast group. The IP time-to-live of a multicast datagram can be used to limit the
range of multicast datagrams.
In order to support multicasting among subnets that are separated by (unicast) routers that do not sup-
port IP multicasting,
mrouted includes support for "tunnels", which are virtual point-to-point links
between pairs of
mrouteds located anywhere in an internet. IP multicast packets are encapsulated for
transmission through tunnels, so that they look like normal unicast datagrams to intervening routers and
subnets. The encapsulation is added on entry to a tunnel and stripped off on exit from a tunnel. By
default, the packets are encapsulated using the IP-in-IP protocol (IP protocol number 4).
The tunnelling mechanism allows
mrouted to establish a virtual internet for the purpose of multicasting
only, which is independent of the physical internet and which may span multiple Autonomous Systems.
mrouted handles multicast routing only; there may or may not be unicast routing software running on
the same machine as mrouted. With the use of tunnels, it is not necessary for mrouted
to have access
to more than one physical subnet in order to perform multicast forwarding.
Invocation
If the
-d option is not specified or if the debug level is specified as 0,
mrouted detaches from the invok-
ing terminal. Otherwise, it remains attached to the invoking terminal and responsive to signals from that
terminal. If
-d is specified with no argument, the debug level defaults to 2. Regardless of the debug
level, mrouted always writes warning and error messages to the system log demon. Nonzero debug lev-
els have the following effects:
level 1 all
syslog messages are also printed to stderr.
level 2 all level 1 messages plus notifications of "significant" events are printed to
stderr.
level 3 all level 2 messages plus notifications of all packet arrivals and departures are printed to
stderr.
Upon startup,
mrouted writes its pid to the file /var/tmp/mrouted.pid.
Configuration
mrouted automatically configures itself to forward on all multicast-capable interfaces (i.e., interfaces
that have the IFF_MULTICAST flag set, excluding the loopback "interface").
mrouted finds other
mrouteds directly reachable via those interfaces. To override the default configuration or to add tunnel
links to other mrouteds, configuration commands may be placed in /etc/mrouted.conf (or an alter-
native file, specified by the -c option). There are four types of configuration commands:
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1