Cisco Systems 78-11741-02 manual Configuring an Msdp Peer, Caching SA State, IPC-480

Configuring Multicast Source Discovery Protocol

MSDP Configuration Task List

Configuring an MSDP Peer

You enable MSDP by configuring an MSDP peer to the local router.

Note The router you specify by Domain Naming System (DNS) name or IP address as an MSDP peer is probably a Border Gateway Protocol (BGP) neighbor. If it is not, see the section “Configuring a Default MSDP Peer” later in this document.

To configure an MSDP peer, use the following commands in global configuration mode as needed. The second command is optional.

Command	Purpose
Router(config)# ip msdp peer {peer-name	Enables MSDP and configures an MSDP peer as specified by
peer-address}[connect-sourcetype number]	the DNS name or IP address.
[remote-as as-number]	If you specify the connect-sourcekeyword, the primary
	address of the specified local interface type and number values
	are used as the source IP address for the TCP connection. The
	connect-sourcekeyword is recommended, especially for
	MSDP peers on a border that peer with a router inside the
	remote domain.
Router(config)# ip msdp description {peer-name	Configures a description for a specified peer to make it easier
peer-address}text	to identify in a configuration or in show command output.

Caching SA State

By default, the router does not cache source/group pairs from received SA messages. Once the router forwards the MSDP SA information, it does not store it in memory. Therefore, if a member joins a group soon after an SA message is received by the local RP, that member will need to wait until the next SA message to hear about the source. This delay is known as join latency.

If you want to sacrifice some memory in exchange for reducing the latency of the source information, you can configure the router to cache SA messages. To have the router cache source/group pairs, use the following command in global configuration mode:

Command	Purpose
Router(config)# ip msdp cache-sa-state [list	Creates SA state (cache source/group pairs). Those pairs that
access-list]	pass the access list are cached.

An alternative to caching the SA state is to request source information from a peer, which is described in the following section, “Requesting Source Information from an MSDP Peer.” If you cache the information, you need not trigger a request for it.

Cisco IOS IP Configuration Guide

IPC-480