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Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
OL-13270-06
Chapter 39 Configuring IP Unicast Routing
Configuring BGP
Configuring BGP Filtering by Neighbor
You can filter BGP advertisements by using autonomous-system-path filters, such as the
as-path
access-list
global configuration command and the
neighbor filter-list
router configuration command.
You can also use access lists with the
neighbor distribute-list
router configuration command.
Distribute-list filters are applied to network numbers. See the
“Controlling Advertising and Processing
in Routing Updates” section on page 39-107
for information about the
distribute-list
command.
You can use route maps on a per-neighbor basis to filter updates and to modify various attributes. You
can apply a route map to either inbound or outbound updates. Only the routes that pass the route map
are sent or accepted in updates. On both inbound and outbound updates, matching is supported based on
autonomous-system path, community, and network numbers. Autonomous-system-path matching
requires the
match
as-path access-lis
t route-map command, community-based matching requires the
match community-list
route-map command, and network-based matching requires the
ip access-list
global configuration command.
Beginning in privileged EXEC mode, follow these steps to apply a per-neighbor route map:
Use the
no neighbor distribute-list
command to remove the access list from the neighbor. Use the
no
neighbor route-map
map-tag
router configuration command to remove the route map from the
neighbor.
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
router bgp
autonomous-system
Enable a BGP routing process, assign it an autonomous-system
number, and enter router configuration mode.
Step 3
neighbor
{
ip-address
|
peer-group name
}
distribute-list
{
access-list-number
|
name
}
{
in
|
out
}
(Optional) Filter BGP routing updates to or from neighbors as
specified in an access list.
Note
You can also use the
neighbor prefix-list
router
configuration command to filter updates, but you cannot use
both commands to configure the same BGP peer.
Step 4
neighbor
{
ip-address
|
peer-group name
}
route-map
map-tag
{
in
|
out
}
(Optional) Apply a route map to filter an incoming or outgoing
route.
Step 5
end
Return to privileged EXEC mode.
Step 6
show ip bgp neighbors
Verify the configuration.
Step 7
copy running-config startup-config
(Optional) Save your entries in the configuration file.
