Configuring Bgp Filtering By Access Lists And Neighbors - Cisco Catalyst 9500 series Configuration Manual

Configuring IP Unicast Routing
Step 3
Step 4
Step 5
Step 6
Step 7

Configuring BGP Filtering by Access Lists and Neighbors

Another method of filtering is to specify an access list filter on both incoming and outbound updates, based
on the BGP autonomous system paths. Each filter is an access list based on regular expressions. (See the
"Regular Expressions" appendix in the Cisco IOS Dial Technologies Command Reference, Release 12.4 for
more information on forming regular expressions.) To use this method, define an autonomous system path
access list, and apply it to updates to and from particular neighbors.
Command or Action
neighbor {ip-address | peer-group name}
distribute-list {access-list-number | name} {in
| out}
Example:
Device(config-router)# neighbor
172.16.4.1 distribute-list 39 in
neighbor {ip-address | peer-group name}
route-map map-tag {in | out}
Example:
Device(config-router)# neighbor
172.16.70.24 route-map internal-map in
end
Example:
Device(config)# end
show ip bgp neighbors
Example:
Device# show ip bgp neighbors
copy running-config startup-config
Example:
Device# copy running-config
startup-config
Routing Configuration Guide, Cisco IOS XE Everest 16.6.x (Catalyst 9500 Switches)
Configuring BGP Filtering by Access Lists and Neighbors
Purpose
(Optional) Filters BGP routing updates to or
from neighbors as specified in an access list.
You can also use the neighbor
Note
prefix-list router configuration
command to filter updates, but you
cannot use both commands to
configure the same BGP peer.
(Optional) Applies a route map to filter an
incoming or outgoing route.
Returns to privileged EXEC mode.
Verifies the configuration.
(Optional) Saves your entries in the
configuration file.
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