3Com Switch 7750 Configuration Guide Guide

448 CHAPTER 45: MSDP CONFIGURATION
Configuration
Prerequisites
Before you configure SA message transmission, perform the following tasks:
■ Configuring a unicast routing protocol.
■ Configuring basic IP multicast functions.
■ Configuring basic PIM-SM functions.
■ Configuring basic MSDP functions.
Configuring the
Transmission and
Filtering of SA Request
Messages
After you configure to request SA messages from MSDP peers, when a router
receives a Join message, it sends an SA request message to the specified remote
MSDP peer, which responds with an SA message that it has cached. After sending
an SA request message, the router will get immediately a response from all active
multicast sources. By default, the router does not send any SA request message to
its MSDP peers upon receipt of a Join message; instead, it waits for the next SA
message.
The SA message that the remote MSDP peer responds with is cached in advance;
therefore, you must enable the SA message caching mechanism in advance.
Typically, only the routers caching SA messages can respond to SA request
messages.
After you have configured a rule for filtering received SA messages, if no ACL is
specified, all SA request messages sent by the corresponding MSDP peer will be
ignored; if an ACL is specified, the SA request messages that satisfy the ACL rule
are received while others are ignored.
Configuring a Rule for
Filtering the Multicast
Sources of SA Messages
An RP filters each registered source to control the information of active sources
advertised in the SA message. An MSDP peer can be configured to advertise only
the (S, G) entries in the multicast routing table that satisfy the filtering rule when
the MSDP creates the SA message; that is, to control the (S, G) entries to be
imported from the multicast routing table to the PIM-SM domain. If the
import-source command is executed without the acl keyword, no source will be
advertised in the SA message.
Tabl e 354 Configure the transmission and filtering of SA request messages
Operation Command Description
Enter system view system-view -
Enter MSDP view msdp -
Enable SA message caching
mechanism
cache-sa-enable
Optional
By default, the router caches
the SA state upon receipt of
an SA message.
Configure to request SA
messages from an MSDP peer
peer peer-address
request-sa-enable
Optional
By default, upon receipt of a
Join message, the router
sends no SA request message
to its MSDP peer but waits for
the next SA message.
Configure to filter the SA
messages received by an
MSDP peer
peer peer-address
sa-request-policy [ acl
acl-number ]
Optional
By default, a router receives
all SA request messages from
the MSDP peer.