I have 2 provider independent prefixes advertised to our current 3 ISPs (ISP-A, ISP-B, ISP-C) via BGP. And I have another separate ISP (ISP-D) with its own IP prefix (ISP owned prefix) running default route only to ISP network (currently not member of BGP).
I plan to join ISP-D to existing BGP, advertising my 2 provider independent prefix plus the ISP owned prefix of ISP-D to this link. However I only want to advertise the ISP owned prefix to ISP-D and not to my other ISP. Meaning this prefix can only be reachable on the internet through ISP-D, inbound and outbound.
I am currently reading on Prefix List Policy Control and I just want to know if I am on the right track. Any ideas how it can be implemented? I will be testing this on lab.
Im thinking of implementing NO-EXPORT community using prefix-list/route-map but I do not prefer applying filtering to every eBGP peer. In this case if i would go for the no-export community I will have to apply "send-community" and "route-map" to my existing peering with 3 ISPs.
I am puzzled why you feel ok to configure all of the EBGP peers with a route map and a prefix list to set the community but do not want to configure the EBGP peer with a prefix list or a distribute list or a route map to prevent advertisement of the provider dependent prefix.
If you try to use the no export or no advertise community you will be advertising the provider dependent prefix to your immediate peers and it seems to me to be a problem if you advertise that prefix to any of the other external peers. So the best solution is some route filtering (distribute list, prefix list, or route map) on the EBGP peers.
Thanks for your response. I currently have outbound filter-list applied on all my eBGP peerings and I worried too much filtering might affect the performance of the router. Using community might be another alternative idea but considering your comments also with Rick below prefix-list or distribute-list will help.
If say I applied both filter-list and prefix-list on the neighbor statement do you see any issue?
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