Cisco Systems 3560 사용자 설명서

This chapter describes how to configure the Multicast Source Discovery Protocol (MSDP) on the 
Catalyst 3560 switch. The MSDP connects multiple Protocol-Independent Multicast sparse-mode 
(PIM-SM) domains.

MSDP is not fully supported in this software release because of a lack of support for Multicast Border 
Gateway Protocol (MBGP), which works closely with MSDP. However, it is possible to create default 
peers that MSDP can operate with if MBGP is not running.

To use this feature, the switch must be running the IP services image (formerly known as the enhanced 
multilayer image [EMI]). 

For complete syntax and usage information for the commands used in this chapter, see the Cisco IOS IP 
Command Reference, Volume 3 of 3: Multicast, Release 12.2 from the Cisco.com page under 
Documentation > Cisco IOS Software > 12.2 Mainline > Command References.

This chapter consists of these sections:

MSDP allows multicast sources for a group to be known to all rendezvous points (RPs) in different 
domains. Each PIM-SM domain uses its own RPs and does not depend on RPs in other domains. An RP 
runs MSDP over the Transmission Control Protocol (TCP) to discover multicast sources in other 
domains. 

An RP in a PIM-SM domain has an MSDP peering relationship with MSDP-enabled devices in another 
domain. The peering relationship occurs over a TCP connection, primarily exchanging a list of sources 
sending to multicast groups. The TCP connections between RPs are achieved by the underlying routing 
system. The receiving RP uses the source lists to establish a source path.

The purpose of this topology is to have domains discover multicast sources in other domains. If the 
multicast sources are of interest to a domain that has receivers, multicast data is delivered over the 
normal, source-tree building mechanism in PIM-SM. MSDP is also used to announce sources sending 
to a group. These announcements must originate at the domain’s RP.