Using TTL to Limit the Multicast Data Sent in SA Messages You can use a TTL value to control what data is encapsulated in the first SA message for every source. Only multicast packets with an IP-header TTL greater than or equal to the ttl argument are sent to the specified MSDP peer. For example, you can limit internal traffic to a TTL of 8. If you want other groups to go to external locations, you must send those packets with a TTL greater than 8. Follow these steps to establish a TTL threshold:
Procedure Configuring MSDP Using TTL to Limit the Multicast Data Sent in SA Messages Command or Action Purpose • For destination, enter the number of the network or host to which the packet is being sent. • For destination-wildcard, enter the wildcard bits in dotted decimal notation to be applied to the destination. Place ones in the bit positions that you want to ignore. Recall that the access list is always terminated by an implicit deny statement for everything. Step 5 end Example: Device(config)#end Returns to privileged EXEC mode. Step 6 show running-config Example: Device#show running-config Verifies your entries. Step 7 copy running-config startup-config Example:
Device#copy running-config startup-config (Optional) Saves your entries in the configuration file. Command or Action Purpose Step 1 enable Example: Device>enable Enables privileged EXEC mode. • Enter your password if prompted. Configuring MSDP 15