System information

Configuring IP Multicast Routing
8-21
Configuring an IP Multicast Static Route
IP multicast static routes (mroutes) enable unicast and multicast packets to take
different paths over combined multicast and unicast network topologies by allowing
multicast packets to travel from the router that is configured with the static multicast
route to the next multicast router, even if there are one or more unicast routers in the
path. The router with the multicast static route uses the IP static multicast route
configuration instead of the unicast routing table to determine the path, and no
information about this IP multicast static route is advertised or redistributed to any
other router on the network.
Use the ip mroute command in Global Configuration mode to configure a multicast
static route which includes the multicast source address, as shown in the following
example:
MOT(config)#ip mroute {<source-address> <mask> <rpf-address>} [<n>]
where:
source-address is the source IP address of the multicast static route.
mask is the source subnetwork IP address of the multicast static route.
rpf-address is the Reverse Path Forwarding neighbor IP address or route.
n is the optional administrative distance of the multicast static route.
Changing the Distance for a Unicast Multicast Route
The distance value is used to compare with the same source in the unicast routing
table. The route that is configured with the lower administrative distance (which can
be either the route in the unicast or DVMRP routing table) takes precedence when
computing the Reverse Path Forwarding (RPF) interface for the source of a multicast
packet. By default, the administrative distance for DVMRP a route is 0, and takes
precedence over unicast routing table routes.
If there are two paths to a source, one through unicast routing (using Protocol
Independent Multicast [PIM] as the multicast routing protocol) and another path using
DVMRP (unicast and multicast routing), and PIM must be the path to a source, use
the ip mroute unicast distance command in Global Configuration mode to increase
the default administrative distance for the DVMRP route, as shown below: