Cisco Systems 3750E Filtering Source-Active Request Messages, Name list access-list-number, 43-11

Chapter 43 Configuring MSDP

Configuring MSDP

Filtering Source-Active Request Messages

By default, only switches that are caching SA information can respond to SA requests. By default, such a switch honors all SA request messages from its MSDP peers and supplies the IP addresses of the active sources.

However, you can configure the switch to ignore all SA requests from an MSDP peer. You can also honor only those SA request messages from a peer for groups described by a standard access list. If the groups in the access list pass, SA request messages are accepted. All other such messages from the peer for other groups are ignored.

Beginning in privileged EXEC mode, follow these steps to configure one of these options. This procedure is optional.

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	ip msdp filter-sa-request ip-address	Filter all SA request messages from the specified MSDP peer.
	name	or
	or	Filter SA request messages from the specified MSDP peer for groups
	ip msdp filter-sa-request {ip-address	that pass the standard access list. The access list describes a multicast
	name} list access-list-number	group address. The range for the access-list-number is 1 to 99.
Step 3
	access-listaccess-list-number {deny	Create an IP standard access list, repeating the command as many times
	permit} source [source-wildcard]	as necessary.
		• For access-list-number, the range is 1 to 99.
		• The deny keyword denies access if the conditions are matched. The
		permit keyword permits access if the conditions are matched.
		• For source, enter the number of the network or host from which the
		packet is being sent.
		• (Optional) For source-wildcard, enter the wildcard bits in dotted
		decimal notation to be applied to the source. 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 4
	end	Return to privileged EXEC mode.
Step 5
	show running-config	Verify your entries.
Step 6
	copy running-config startup-config	(Optional) Save your entries in the configuration file.

To return to the default setting, use the no ip msdp filter-sa-request{ip-address name} global configuration command.

This example shows how to configure the switch to filter SA request messages from the MSDP peer at 171.69.2.2. SA request messages from sources on network 192.4.22.0 pass access list 1 and are accepted; all others are ignored.

Switch(config)# ip msdp filter sa-request 171.69.2.2 list 1

Switch(config)# access-list 1 permit 192.4.22.0 0.0.0.255

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02		43-11