3Com S7902E, Configuration Manual

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1-14
To do... Use the command... Remarks
Enter system view
system-view
—
Enter public instance MSDP view
or VPN instance MSDP view msdp [ vpn-instance
vpn-instance-name ]
—
Enable the device to send SA
request messages peer peer-address
request-sa-enable
Optional
Disabled by default
Configure a filtering rule for SA
request messages
peer peer-address
sa-request-policy [ acl
acl-number ]
Optional
SA request messages are
not filtered by default
Before you can enable the device to send SA requests, be sure to disable the SA message cache
mechanism.
Configuring SA Message Filtering Rules
By configuring an SA message creation rule, you can enable the router to filter the (S, G) entries to be
advertised when creating an SA message, so that the propagation of messages of multicast sources is
controlled.
By configuring a filtering rule for receiving or forwarding SA messages, you can enable the router to filter
the (S, G) forwarding entries to be advertised when receiving or forwarding an SA message, so that the
propagation of multicast source information is controlled at SA message reception or forwarding.
By configuring a TTL threshold for multicast data packet encapsulation in SA messages, you can control
the multicast data packet encapsulation in SA messages and limit the propagation range of SA
messages:
z
Before creating an SA message with an encapsulated multicast data packet, the router checks the
TTL value of the multicast data packet. If the TTL value is less than the threshold, the router does
not create an SA message; if the TTL value is greater than or equal to the threshold, the router
encapsulates the multicast data in an SA message and sends the SA message out.
z
Upon receiving an SA message with an encapsulated multicast data packet, the router decrements
the TTL value of the multicast packet by 1 and then checks the TTL value. If the TTL value is less
than the threshold, the router does not forward the SA message to the designated MSDP peer; if
the TTL value is greater than or equal to the threshold, the router re-encapsulates the multicast
data in an SA message and sends the SA message out.