HP-UX Reference (11i v1 05/09) - 1M System Administration Commands A-M (vol 3)

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 support
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 transmis-
sion 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 invoking
terminal. Otherwise, it remains attached to the invoking terminal and responsive to signals from that ter-
minal. 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. Non-zero debug levels
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 alternative file,
specified by the -c option). There are four types of configuration commands:
HP-UX 11i Version 1: September 2005 − 1 − Hewlett-Packard Company Section 1M−−529