User's Manual

Configuring Multicast Source Discovery Protocol
MSDP Configuration Task List
IPC-482
Cisco IOS IP Configuration Guide
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.
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:
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
Command Purpose
Router(config)# ip msdp redistribute [list
access-list] [asn as-access-list] [route-map map-name]
Advertises (S, G) pairs that pass the access list or route map
to other domains.
Command Purpose
Router(config)# ip msdp filter-sa-request
{peer-address | peer-name}
Filters all SA request messages from the specified MSDP
peer.
Router(config)# ip msdp filter-sa-request
{peer-address | peer-name} list access-list
Filters SA request messages from the specified MSDP peer
for groups that pass the standard access list. The access list
describes a multicast group address.