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Configuring IP Multicast Routing

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Configuring a Rendezvous Point

If you are using PIM-DM throughout the multicast network, configuring a
rendezvous point is an optional task. There are two ways of configuring
a rendezvous point for a router. Notice that we did not say, "configuring a
router to be" a rendezvous point. You can manually specify the IP address of
the RP on a router, or you can enable Auto-RP.

Because multiple RPs may exist in a multicast network, the Auto-RP func-

tion aids by distributing the RP information across a multicast network. Dif-
ferent multicast groups may use different RPs, so this feature keeps track of
which groups are using which RP. It will also fine-tune the leaf router's RP
by choosing the RP nearest to the leaf. If you don't like to use static routes
in a unicast network, you probably don't want to statically configure multi-
cast RPs either.

Because there are two ways of configuring rendezvous points, we will

describe both in the following subsections.

Manual RP Configuration

The syntax for the manual RP configuration command is very simple, ip
pim rp-address ip-address [group-access-list-number]
[override]

. The ip-address is the IP address of the router that is the RP.

The access list number is for a standard IP access list (199) or an expanded
range from 1300 to 1999. These lists are used to define which multicast
groups can or cannot use this RP. If no access list is specified, all multicast groups
will use the configured RP. Finally, the override option can be used to over-
ride any RP information that may be learned via an Auto-RP update. The
static RP takes precedence over any Auto-RP-learned RP. Here is a sample
configuration for manual RP configuration:

RouterA#conf t

Enter configuration commands, one per line. End with CNTL/Z.

RouterA(config)#ip pim rp-address 172.16.1.253 50 override

RouterA(config)#^Z

RouterA#

Here is a look at the router after the execution. Notice that the command

is a global command. Following the global configuration, you will see
access-list 50. The list allows only groups within the range of 224.0.0.0 to
224.255.255.255 to use 172.16.1.253 as the RP. Other groups will need

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