Cisco Systems 78-11741-02 manual Setting Up Auto-RP in a New Internetwork, Choosing a Default RP

Configuring IP Multicast Routing

Configuring Auto-RP

Setting Up Auto-RP in a New Internetwork

If you are setting up Auto-RP in a new internetwork, you do not need a default RP because you configure all the interfaces for sparse-dense mode. Follow the process described in the section “Adding Auto-RP to an Existing Sparse Mode Cloud,” except that you should omit the first step of choosing a default RP.

Adding Auto-RP to an Existing Sparse Mode Cloud

The following sections contain suggestions for the initial deployment of Auto-RP into an existing sparse mode cloud, to minimize disruption of the existing multicast infrastructure.

Choosing a Default RP

Sparse mode environments need a default RP; sparse-dense mode environments do not. If you have sparse-dense mode configured everywhere, you need not choose a default RP.

Adding Auto-RP to a sparse mode cloud requires a default RP. In an existing PIM sparse mode region, at least one RP is defined across the network that has good connectivity and availability. That is, the ip pim rp-addresscommand is already configured on all routers in this network.

Use that RP for the global groups (for example, 224.x.x.x and other global groups). There is no need to reconfigure the group address range that RP serves. RPs discovered dynamically through Auto-RP take precedence over statically configured RPs. Assume it is desirable to use a second RP for the local groups.

Announcing the RP and the Group Range It Serves

Find another router to serve as the RP for the local groups. The RP-mapping agent can double as an RP itself. Assign the whole range of 239.x.x.x to that RP, or assign a subrange of that (for example, 239.2.x.x).

To designate that a router is the RP, use the following command in global configuration mode:

Command	Purpose
Router(config)# ip pim send-rp-announce type number	Configures a router to be the RP.
scope ttl-value [group-listaccess-list]
[interval seconds]

To change the group ranges this RP optimally will serve in the future, change the announcement setting on the RP. If the change is valid, all other routers automatically will adopt the new group-to-RP mapping.

The following example advertises the IP address of Ethernet interface 0 as the RP for the administratively scoped groups:

ip pim send-rp-announce ethernet0 scope 16 group-list 1 access-list 1 permit 239.0.0.0 0.255.255.255

Assigning the RP Mapping Agent

The RP mapping agent is the router that sends the authoritative discovery packets telling other routers which group-to-RP mapping to use. Such a role is necessary in the event of conflicts (such as overlapping group-to-RP ranges).

Cisco IOS IP Configuration Guide

IPC-407