Cisco Systems 78-11741-02 manual Configuring Auto-RP, Configuring a Rendezvous Point, IPC-406

Configuring IP Multicast Routing

Configuring Auto-RP

Configuring a Rendezvous Point

If you configure PIM to operate in sparse mode, you must also choose one or more routers to be rendezvous points (RPs). You need not configure the routers to be RPs; they learn how to become RPs themselves. RPs are used by senders to a multicast group to announce their existence and by receivers of multicast packets to learn about new senders. The Cisco IOS software can be configured so that packets for a single multicast group can use one or more RPs.

The RP address is used by first hop routers to send PIM register messages on behalf of a host sending a packet to the group. The RP address is also used by last hop routers to send PIM join and prune messages to the RP to inform it about group membership. You must configure the RP address on all routers (including the RP router).

A PIM router can be an RP for more than one group. Only one RP address can be used at a time within a PIM domain. The conditions specified by the access list determine for which groups the router is an RP.

To configure the address of the RP, use the following command on a leaf router in global configuration mode:

Command	Purpose
Router(config)# ip pim rp-address rp-address	Configures the address of a PIM RP.
[access-list] [override]

Configuring Auto-RP

Auto-RP is a feature that automates the distribution of group-to-RP mappings in a PIM network. This feature has the following benefits:

•The use of multiple RPs within a network to serve different group ranges is easy.

•It allows load splitting among different RPs and arrangement of RPs according to the location of group participants.

•It avoids inconsistent, manual RP configurations that can cause connectivity problems.

Multiple RPs can be used to serve different group ranges or serve as backups of each other. To make Auto-RP work, a router must be designated as an RP-mapping agent, which receives the RP-announcement messages from the RPs and arbitrates conflicts. The RP-mapping agent then sends the consistent group-to-RP mappings to all other routers. Thus, all routers automatically discover which RP to use for the groups they support.

Note If you configure PIM in sparse mode or sparse-dense mode and do not configure Auto-RP, you must statically configure an RP as described in the section “Assigning an RP to Multicast Groups” later in this chapter.

Note If router interfaces are configured in sparse mode, Auto-RP can still be used if all routers are configured with a static RP address for the Auto-RP groups.

Cisco IOS IP Configuration Guide

IPC-406