Dell Force10 C150 Configuration Manual page 255

Refer to Chapter 8, "IP Access Control Lists (ACL), Prefix Lists, and Route-maps," on page 133
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.
Use these commands in the following sequence, starting in the CONFIGURATION mode to filter routes
using prefix lists.
Step Command Syntax
ip prefix-list
1 prefix-name
seq
2
sequence-number
permit } {any |
ip-prefix
exit
3
router bgp
4 as-number
neighbor {
5
ip-address
peer-group-name
{ in | out }
prefix-list-name
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.
To view the BGP configuration, use the
prefix list configuration, use the
EXEC Privilege mode.
Command Mode
CONFIGURATION
{ deny |
CONFIG-PREFIX
[ ge | le ] }
LIST
CONFIG-PREFIX
LIST
CONFIGURATION
| CONFIG-ROUTER-
} distribute-list
BGP
permit 0.0.0.0/0 le 32
show config
show ip prefix-list detail
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 Chapter 8, "IP Access Control Lists
(ACL), Prefix Lists, and Route-maps," on
page 133 for information on 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
neighbor's IP address or the peer group's
name.
• prefix-list-name:
configured prefix list.
in: apply the prefix list to inbound routes.
•
out: apply the prefix list to outbound
•
routes.
).
command in the ROUTER BGP mode. To view a
show ip prefix-list summary
or
Border Gateway Protocol IPv4 (BGPv4) | 255
for
peer-group-name: enter the
enter the name of a
commands in