Reference Guide

228 | Border Gateway Protocol IPv4 (BGPv4)
www.dell.com | support.dell.com
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.
To view the BGP configuration, use the
show config command in the ROUTER BGP mode. To view a
prefix list configuration, use the
show ip prefix-list detail or show ip prefix-list summary commands in
EXEC Privilege mode.
Use these commands in the following sequence, starting in the CONFIGURATION mode to filter routes
using a route map.
5
neighbor {ip-address |
peer-group-name} distribute-list
prefix-list-name {in | out}
CONFIG-ROUTER-
BGP
Filter routes based on the ccriteria in the
configured prefix list. Configure the
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.
Step Command Syntax Command Mode Purpose
1 route-map map-name [permit |
deny] [sequence-number]
CONFIGURATION Create a route map and assign it a name.
2
{match | set} CONFIG-ROUTE-MAP Create multiple route map filters with a
match or set action.
Refer to Access Control Lists (ACLs) for
information on configuring route maps.
3
exit
CONFIG-ROUTE-MAP Return to the CONFIGURATION mode.
4
router bgp as-number CONFIGURATION Enter ROUTER BGP mode.
Step Command Syntax Command Mode Purpose