Cisco Systems 78-11741-02 manual Controlling Source Information That Your Router Forwards, IPC-482

Configuring Multicast Source Discovery Protocol

MSDP Configuration Task List

To further restrict which registered sources are advertised, use the following command in global configuration mode. The access list or autonomous system path access list determines which (S, G) pairs are advertised.

Command	Purpose
Router(config)# ip msdp redistribute [list	Advertises (S, G) pairs that pass the access list or route map
access-list] [asn as-access-list][route-mapmap-name]	to other domains.

Note The ip msdp redistribute global configuration command could also be used to advertise sources that are known to the RP but not registered. However, we strongly recommend that you NOT originate advertisements for sources that have not registered with the RP.

Filtering SA Request Messages

By default, only routers that are caching SA information can respond to SA request messages. By default, such a router honors all SA request messages from its MSDP peers. That is, it will supply the IP addresses of the sources that are active.

However, you can configure the router to ignore all SA request messages from an MSDP peer. Or, you can honor only those SA request messages from a peer for groups described by a standard access list. If the access list passes, SA request messages will be accepted. All other such messages from the peer for other groups will be ignored.

To configure one of these options, use either of the following commands in global configuration mode:

Command	Purpose
Router(config)# ip msdp filter-sa-request	Filters all SA request messages from the specified MSDP
{peer-address peer-name}	peer.
Router(config)# ip msdp filter-sa-request	Filters SA request messages from the specified MSDP peer
{peer-address peer-name}list access-list	for groups that pass the standard access list. The access list
	describes a multicast group address.

Controlling Source Information That Your Router Forwards

By default, the router forwards all SA messages it receives to all of its MSDP peers. However, you can prevent outgoing messages from being forwarded to a peer by using a filter or by setting a time-to-live (TTL) value. These methods are described in the following sections.

Using an MSDP Filter

By creating an MSDP filter, you can do one of the following:

•Filter all source/group pairs

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

•Filter based on match criteria in a route map

Cisco IOS IP Configuration Guide

IPC-482