topic Re: Advertising a more specific route with BGP in General Topics

Advertising a more specific route with BGP

alannnnnnn — Mon, 01 Apr 2024 17:19:52 GMT

Hi,

I have a check point receiving 10.0.0.0/8 via BGP, is it possible to advertise 10.0.0.1/32 to a different peer via BGP? 10.0.0.1/32 is not on my route table, only 10.0.0.0/8 is on the route table.

I'm assuming a combination of route maps or aggregation can solve this?

Re: Advertising a more specific route with BGP

Bob_Zimmerman — Mon, 01 Apr 2024 19:21:10 GMT

Possible, yes, but the route has to come from somewhere. Typically, it comes from a route on the system which you then use a route-map to match and redistribute into BGP.

Re: Advertising a more specific route with BGP

alannnnnnn — Mon, 01 Apr 2024 19:37:21 GMT

so, I would have to add a static route then, no other way around that?

Re: Advertising a more specific route with BGP

Bob_Zimmerman — Mon, 01 Apr 2024 19:43:18 GMT

Or redistribute an interface route or something, yes. You can't just say "Hey BGP, tell my neighbors I know how to reach 10.20.30.40" if you don't actually know how to reach that address.

What goal are you trying to accomplish?

Re: Advertising a more specific route with BGP

alannnnnnn — Mon, 01 Apr 2024 19:49:22 GMT

Instead of advertising 10.0.0.0/8 to my EBGP peer, I want to advertise a /32 instead. The next hop on my route table would be the same. The EBGP is on the other side of a VPN tunnel, the tunnel interfaces are on 169. and they are the peer IPs.

Re: Advertising a more specific route with BGP

CheckPointerXL — Tue, 16 Apr 2024 08:28:32 GMT

the workaround that i suggest and i usually use is nat pool:

https://support.checkpoint.com/results/sk/sk179549