After receiving a Source Active (SA) message encapsulated with a multicast data packet, an MSDP peer forwards the SA message to a specified remote MSDP peer only when the TTL value of the multicast packet is greater than the set threshold.
Setting the TTL threshold can limit the transmission scope of a multicast packet contained in an SA message. After receiving an SA message containing a multicast packet, an MSDP peer checks the TTL value in the IP header of the multicast packet. If the TTL value is smaller than or equal to the threshold, the MSDP peer does not forward the SA message to a specific remote peer. If the TTL value is greater than the threshold, the MSDP peer reduces the TTL value in the IP header of the multicast packet by 1, and then encapsulates the multicast packet in an SA message and sends it out.
msdp [ vpn-instance vpn-instance-name ]
peer peer-address minimum-ttl ttl
After receiving an SA message containing a multicast data packet, an MSDP peer forwards the SA message to the specified remote MSDP peer only when the TTL value of the multicast packet is greater than the threshold.
The parameters of the command are explained as follows:
peer-address: specifies the address of a remote MSDP peer.
ttl: specifies the value of the TTL threshold. By default, the value is 0.