Cisco Systems 3750E Route-map map-tag in out, Ip as-path access-list access-list-number, 38-55

Chapter 38 Configuring IP Unicast Routing

Configuring BGP

path, community, and network numbers. Autonomous system path matching requires the match as-pathaccess-list route-map command, community based matching requires the match community-listroute-map command, and network-based matching requires the ip access-listglobal configuration command.

Beginning in privileged EXEC mode, follow these steps to apply a per-neighbor route map:

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	router bgp autonomous-system	Enable a BGP routing process, assign it an AS number, and enter
		router configuration mode.
Step 3
	neighbor {ip-address peer-group name}	(Optional) Filter BGP routing updates to or from neighbors as
	distribute-list{access-list-number name}	specified in an access list.
	{in out}	Note You can also use the neighbor prefix-listrouter
		configuration command to filter updates, but you cannot use
		both commands to configure the same BGP peer.
Step 4
	neighbor {ip-address peer-group name}	(Optional) Apply a route map to filter an incoming or outgoing
	route-map map-tag{in out}	route.
Step 5
	end	Return to privileged EXEC mode.
Step 6
	show ip bgp neighbors	Verify the configuration.
Step 7
	copy running-config startup-config	(Optional) Save your entries in the configuration file.

Use the no neighbor distribute-listcommand to remove the access list from the neighbor. Use the no neighbor route-mapmap-tagrouter configuration command to remove the route map from the neighbor.

Another method of filtering is to specify an access list filter on both incoming and outbound updates, based on the BGP autonomous system paths. Each filter is an access list based on regular expressions. (See the “Regular Expressions” appendix in the Cisco IOS Dial Technologies Command Reference, Release 12.2 for more information on forming regular expressions.) To use this method, define an autonomous system path access list, and apply it to updates to and from particular neighbors.

Beginning in privileged EXEC mode, follow these steps to configure BGP path filtering:

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	ip as-path access-list access-list-number	Define a BGP-related access list.
	{permit deny} as-regular-expressions
Step 3
	router bgp autonomous-system	Enter BGP router configuration mode.
Step 4
	neighbor {ip-address peer-group name}	Establish a BGP filter based on an access list.
	filter-list{access-list-number name} {in
	out weight weight}
Step 5
	end	Return to privileged EXEC mode.
Step 6
	show ip bgp neighbors [paths	Verify the configuration.
	regular-expression]
Step 7
	copy running-config startup-config	(Optional) Save your entries in the configuration file.
		Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02			38-55