BGP Route Filtering using Prefix Lists and Route Maps

Note: this is an elementary example. A more realistic implementation will include ranges of subnets and more granular filtering

In this demonstration, BGP is operating across 3 separate Autonomous Systems. Objective is to filter out the /26 network being advertised to R2 using a Prefix-List and Route-Map on R0.

1. First we create the Prefix-List to deny traffic from the /26 network
2. Then we can create a Route-Map and match the list
3. Finally we will attach the route-map to our BGP process
(You will need to reset/refresh the BGP TCP sessions on R2 for changes to take effect on the BGP table and routing table)

On R0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ip prefix-list LIST1 seq 5 deny 192.168.1.128/26
ip prefix-list LIST1 seq 10 permit 0.0.0.0/0 le 32

route-map MAP1 permit 10
match ip address prefix-list LIST1

router bgp 6500
neighbor 10.2.2.2 route-map MAP1 out

On R2
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
clear ip bgp *
show ip bgp

Видео BGP Route Filtering using Prefix Lists and Route Maps канала Bellagio Sampler