Does anyone have any experience configuring BGP filters? If so, here is my dilemma: One of our core routers is hooked up to ISP A via BGPv4 and is recieving the full routing table of which is in excess of 100,000 networks. I would like to have it recieve routes only from ISP A's AS, and NOT every other AS it knows. I have configured my test lab with 3 routers and each having a different AS (100, 200, 300) lets call the routers R1, R2, R3, respectively. In this situation i want allow incoming routes only originating from R2(AS200) and not R3(AS300).I used a as-path access list to do the filtering and applied it to R1's external interface. My access-list is as follows. ip as-path access-list 1 permit ^200$ neighbor 173.16.1.2 filter-list 1 in Heres the config for all three routers R1 router bgp 100 no sync network 173.16.1.0 mask 255.255.255.0 neighbor 173.16.1.2 remote-as 200 neighbor 173.16.1.2 filter-list 1 in ip as-path access-list 1 permit ^200$ R2 router bgp 200 network 173.16.1.0 mask 255.255.255.0 network 174.16.2.0 mask 255.255.255.0 network 178.16.2.0 mask 255.255.255.0 neighbor 173.16.1.1 remote-as 100 neighbor 174.16.2.2 remote-as 300 R3 router bgp 300 network 174.16.2.0 mask 255.255.255.0 network 179.16.3.0 mask 255.255.255.0 netwokr 174.16.2.1 remote-as 200 Also note that R2 has a direct connection to R1 and R3. Connectivity is established between all three routers. With the access-list i have will it block routes from AS300? Many thanks in advance!

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