3com 8807 User Guide

C

HAPTER

 45: MSDP C

ONFIGURATION

Multicast group addresses are described in ACL. If no ACL is specified, all SA 
request messages sent by the corresponding MSDP peer will be ignored. If an ACL 
is specified, only SA request messages of the groups permitted by the ACL will be 
processed.

Controlling of source information also includes that of forwarding and receiving 
source information besides that of creating source information. The outbound 
filter or time to live (TTL) threshold of SA messages can be used to control the SA 
message forwarding. By default, all SA messages are forwarded to other MSDP 
peers.

MSDP outbound filter of are functional in:

■

Filtering off all the (S, G) entries

■

Forwarding only the SA messages permitted by the advanced ACL

Please perform the following configurations in MSDP view.

An SA message with encapsulated data can reach the specified MSDP peer only 
when the TTL in its IP header is no less than the threshold. Therefore, the 
forwarding of SA messages with encapsulated data can be controlled by 
configuring the TTL threshold.

For example, you can set the TTL threshold for intra-domain multicast traffic as 10 
if you wish to restrict SA messages with TTL less than or equal to 10 carrying 
encapsulated data from being propagated. If you set the TTL threshold greater 
than 10, then they can be propagated to outside.

Please perform the following configurations in MSDP view.

The default value of TTL threshold is 0.

Table 474   Use MSDP outbound filter to control the source information forwarded

Filter off all the SA messages to a specified 
MSDP peer 

peer peer-address sa-policy export 

Forward the SA messages permitted by the 
advanced ACL to a specified MSDP peer 

peer peer-address sa-policy export acl 
acl-number 

Remove the filtering over the source 
information forwarded 

undo peer peer-address sa-policy export

Table 475   Use TTL to filter SA messages with encapsulated data

Filter off the multicast data encapsulated in 
the first SA message aiming at a specified 
MSDP peer 

peer peer-address minimum-ttl ttl 

Remove the TTL threshold configuration 

undo peer peer-address minimum-ttl