System information

Configuring Routing Policy
7-7
Example
This configuration example
filters BGP updates from a BGP neighbor. It configures
Access List 4 by specifying its permit and deny conditions. Access list 4 prohibits the
propagation of networks specified in the deny statements (10.0.0.0, 162.15.0.0, and
180.10.0.0) and permits all others.
access-list 4 deny 10.0.0.0 0.255.255.255 any
access-list 4 deny 162.15.0.0 0.0.255.255 any
access-list 4 deny 180.10.0.0 0.0.255.255 any
access-list 4 permit any
The following commands enable BGP, specify an autonomous system, and apply
Access List 4 to a neighbor. The example instructs the router to pass all network
information received from BGP neighbor 156.30.10.22 through access list 4.
router bgp 100
neighbor 160.25.15.10 distribute-list 4 in
Configuring an AS-path Access-list
The permit and deny conditions in an AS-path access list apply to AS numbers. The
neighbor filter-list command applies an AS-path access list for inbound and
outbound updates to a BGP neighbor. The match AS-path command adds a match
clause to a route map.
To define an AS-path access list, use the ip as-path access-list command, as shown
below:
MOT(config)#ip as-path access-list <access-list-number> {permit | deny}
<path-expression>
where:
access-list-number is the access list number.
path-expression is a valid path expression.
Note: All lists have an assumed deny all entry as the last statement. If no
matches exist, the route or set is denied.