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594 CHAPTER 31: MSDP CONFIGURATION
Configuring the
Transmission and
Filtering of SA Request
Messages
After you enable sending SA request messages to 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 an 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 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.
Table 649 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.
Enable sending SA request
messages to the 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 a rule for
filtering the SA messages
to be 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.
Table 650 Configure a rule for filtering multicast sources using SA messages
Operation Command Description
Enter system view system-view -
Enter MSDP view msdp -
Configure to filter multicast
sources using SA messages
import-source [ acl
acl-number ]
Optional
By default, all the (S, G) entries in
the domain are advertised in the
SA message.