3Com Switch 7750 Configuration Guide Guide

Configuring SA Message Transmission 449
Configuring a Rule for
Filtering Received and
Forwarded SA Messages
Besides the creation of source information, controlling multicast source
information allows you to control the forwarding and reception of source
information. You can control the reception of SA messages using the MSDP
inbound filter (corresponding to the import keyword); you can control the
forwarding of SA messages by using either the MSDP outbound filter
(corresponding to the export argument) or the TTL threshold. By default, an
MSDP peer receives and forwards all SA messages.
MSDP inbound/outbound filter implements the following functions:
■ Filtering out all (S, G) entries
■ Receiving/forwarding only the SA messages permitted by advanced ACL rules
An SA message carrying encapsulated data can reach the specified MSDP peer
outside the domain only when the TTL in its IP header exceeds the threshold;
therefore, you can control the forwarding of SA messages that carry encapsulated
data by configuring the TTL threshold.
Configuring SA Message
Cache
With the SA message caching mechanism enabled on the router, the group that a
new member subsequently joins can obtain all active sources directly from the SA
cache and join the corresponding SPT source tree, instead of waiting for the next
SA message.
You can configure the number of SA entries cached in each MSDP peer on the
router by executing the following command, but the number must be within the
system limit. The maximum number of cached SA messages on each MSDP peer
Table 355 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.
Table 356 Configure a rule for filtering received and forwarded SA messages
Operation Command Description
Enter system view system-view -
Enter MSDP view msdp -
Configure to filter SA
messages to be received or
forwarded
peer peer-address sa-policy {
import | export } [ acl
acl-number ]
Optional
By default, no filtering is
imposed on SA messages to
be received or forwarded,
namely all SA messages from
MSDP peers are received or
forwarded.
Configure the minimum TTL
for the multicast packets sent
to the specified MSDP peer
peer peer-address
minimum-ttl ttl-value
Optional
By default, the value of TTL
threshold is 0.