Dell Force10 Z9000 FTOS Configuration Guide for Z9000 System - Page 213

• AS-PATH ACLs (using neighbor filter-list command) • route maps (using neighbor route-map command) Prior to filtering BGP routes, you must create the prefix list, AS-PATH ACL, or route map to be used. Refer to Chapter 6, "Access Control Lists (ACLs)," on page 89 for configuration information on prefix lists, AS-PATH ACLs, and route maps. Note: When you configure a new set of BGP policies, always reset the neighbor or peer group by entering the clear ip bgp command in EXEC Privilege mode to ensure the changes are made. Use these commands in the following sequence, starting in the CONFIGURATION mode to filter routes using prefix lists. Step Command Syntax Command Mode Purpose 1 ip prefix-list prefix-name CONFIGURATION Create a prefix list and assign it a name. 2 seq sequence-number {deny | CONFIG-PREFIX LIST Create multiple prefix list filters with a deny permit} {any | ip-prefix [ge | le] } or permit action. ge: Minimum prefix length to be matched le: maximum prefix length to me matched Refer to Chapter 6, "Access Control Lists (ACLs)," on page 89 for information on configuring prefix lists. 3 exit CONFIG-PREFIX LIST Return to the CONFIGURATION mode. 4 router bgp as-number CONFIGURATION Enter ROUTER BGP mode. 5 neighbor {ip-address | CONFIG-ROUTER-BGP Filter routes based on the criteria in the peer-group-name} distribute-list configured prefix list. Configure the prefix-list-name {in | out} following parameters: • ip-address or peer-group-name: enter the neighbor's IP address or the peer group's name. • prefix-list-name: enter the name of a configured prefix list. • in: apply the prefix list to inbound routes. • out: apply the prefix list to outbound routes. As a reminder, below are some rules concerning prefix lists: • If the prefix list contains no filters, all routes are permitted. • If none of the routes match any of the filters in the prefix list, the route is denied. This action is called an implicit deny. (If you want to forward all routes that do not match the prefix list criteria, you must configure a prefix list filter to permit all routes. For example, you could have the following filter as the last filter in your prefix list permit 0.0.0.0/0 le 32). • Once a route matches a filter, the filter's action is applied. No additional filters are applied to the route. Border Gateway Protocol | 213