Dell Force10 S4810P Configuration Manual page 227

• AS-PATH ACLs (using
• route maps (using
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
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
1
ip prefix-list prefix-name
2
seq sequence-number { deny |
permit } {any | ip-prefix [ ge | le ] }
3
exit
4
router bgp as-number
5
neighbor {ip-address |
peer-group-name} distribute-list
prefix-list-name { in | out }
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
• Once a route matches a filter, the filter's action is applied. No additional filters are applied to the route.
neighbor filter-list
command)
neighbor route-map
Command Mode
CONFIGURATION
CONFIG-PREFIX LIST
CONFIG-PREFIX LIST
CONFIGURATION
CONFIG-ROUTER-BGP
permit 0.0.0.0/0 le 32
command)
for configuration information on prefix
Purpose
Create a prefix list and assign it a name.
Create multiple prefix list filters with a deny
or permit action.
ge : Minimum prefix length to be matched
le : maximum prefix length to me matched
Refer to
(ACLs)," on page 89
configuring prefix lists.
Return to the CONFIGURATION mode.
Enter ROUTER BGP mode.
Filter routes based on the criteria 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.
).
Chapter 6, "Access Control Lists
for information on
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