Cisco Systems 78-11741-02 manual Controlling Source Information That Your Router Receives, IPC-483

Configuring Multicast Source Discovery Protocol

MSDP Configuration Task List

To apply an MSDP filter, use the following commands in global configuration mode as needed:

Command	Purpose
Router(config)# ip msdp sa-filter out {peer-address	Filters all SA messages to the specified MSDP peer.
peer-name}
Router(config)# ip msdp sa-filter out	To the specified MSDP peer, passes only those SA messages
{peer--address peer-name}list access-list	that pass the extended access list.
Router(config)# ip msdp sa-filter out {peer-address	To the specified MSDP peer, passes only those SA messages
peer-name}route-mapmap-name	that meet the match criteria in the route map map-tagvalue.

Using TTL to Limit the Multicast Data Sent in SA Messages

You can use TTL to control what data will be encapsulated in the first SA message for every source. For example, you could limit internal traffic to a TTL of 8. If you want other groups to go to external locations, you would need to send those packets with a TTL greater than 8.

To establish a TTL threshold, use the following command in global configuration mode:

Command	Purpose
Router(config)# ip msdp ttl-threshold {peer-address	Limits which multicast data will be encapsulated in the first SA
peer-name}ttl-value	message to the specified MSDP peer.

Controlling Source Information That Your Router Receives

By default, the router receives all SA messages its MSDP RPF peers send to it. However, you can control the source information you receive from MSDP peers by filtering incoming SA messages. In other words, you can configure the router not to accept them.

You can do one of the following to control the source information you receive from MSDP peers:

•Filter all incoming SA messages from an MSDP peer

•Specify an extended access list to pass certain source/group pairs

•Filter based on match criteria in a route map

To apply a filter, use the following commands in global configuration mode as needed:

Command	Purpose
Router(config)# ip msdp sa-filter in {peer-address	From the specified MSDP peer, filters all SA messages
peer-name}	received.
Router(config)# ip msdp sa-filter in {peer-address	From the specified MSDP peer, passes incoming SA messages
peer-name}list access-list	that pass the extended access list.
Router(config)# ip msdp sa-filter in {peer-address	From the specified MSDP peer, passes only those SA messages
peer-name}route-mapmap-name	that meet the match criteria in the route map map-namevalue.

Cisco IOS IP Configuration Guide

IPC-483