topic Re: BGP advertise and prefix-list in General Topics

BGP advertise and prefix-list

melcu — Mon, 15 Sep 2025 19:15:13 GMT

Hi Mates,

Struggling with BGP and route advertise using routemaps and prefix lists.

Config:

set bgp external remote-as 123 on
set bgp external remote-as 123 local-address 10.200.0.1 on
set bgp external remote-as 123 export-routemap "dist_bgp" preference 1 on
set bgp external remote-as 123 peer 172.25.42.1 on
set bgp external remote-as 123 peer 172.25.42.1 multihop on
set bgp external remote-as 123 peer 172.25.42.1 holdtime 180
set bgp external remote-as 123 peer 172.25.42.1 keepalive 60
set bgp external remote-as 123 peer 172.25.42.1 ping on
set bgp external remote-as 123 peer 172.25.42.1 export-routemap "dist_bgp" preference 1 on
set bgp external remote-as 123 peer 172.25.42.3 on
set bgp external remote-as 123 peer 172.25.42.3 multihop on
set bgp external remote-as 123 peer 172.25.42.3 holdtime 180
set bgp external remote-as 123 peer 172.25.42.3 keepalive 60
set bgp external remote-as 123 peer 172.25.42.3 ping on
set bgp external remote-as 123 peer 172.25.42.3 export-routemap "dist_bgp" preference 1 on

set prefix-list bgp-nets sequence-number 5 prefix 83.166.213.32/32 exact
set prefix-list bgp-nets sequence-number 10 prefix 83.166.213.102/32 exact
set prefix-list bgp-nets sequence-number 15 prefix 83.166.213.103/32 exact
set prefix-list bgp-nets sequence-number 20 prefix 83.166.213.99/32 exact
set prefix-list bgp-nets sequence-number 25 prefix 83.166.213.200/32 exact
set prefix-list bgp-nets sequence-number 30 prefix 83.166.234.84/32 exact

set routemap redist_to_bgp id 10 on
set routemap redist_to_bgp id 10 allow
set routemap redist_to_bgp id 10 match prefix-list bgp-nets preference 1 on
set routemap redist_to_bgp id 10 match protocol bgp

set bgp external remote-as 123 export-routemap redist_to_bgp preference 1 o
set bgp external remote-as 123 peer 172.25.42.1 export-routemap redist_to_bgp preference 1 on
set bgp external remote-as 123 peer 172.25.42.3 export-routemap redist_to_bgp preference 1 on

Frankly I'm not sure why is not working 😞 but It doesn't advertise nothing to the peer member

[Local SGM] demo-clu-ch01-01:1> show bgp peer 172.25.42.1 advertise

[Local SGM] demo=clu-ch01-01:1>

What am I missing from this ?! 😞

Many thanks

Re: BGP advertise and prefix-list

the_rock — Mon, 15 Sep 2025 19:33:26 GMT

Maybe this is wrong?

set routemap redist_to_bgp id 10 match protocol bgp

Keep in mind, protocol has to be ORIGINATING one, not protocol supposed to be advertised.

Andy

Re: BGP advertise and prefix-list

melcu — Mon, 15 Sep 2025 19:38:06 GMT

I was playing with it.

set routemap redist_to_bgp id 10 on
set routemap redist_to_bgp id 10 allow
set routemap redist_to_bgp id 10 match prefix-list bgp-nets preference 1 on

Deleted but still nothing 😞

Re: BGP advertise and prefix-list

the_rock — Mon, 15 Sep 2025 19:40:10 GMT

You leave line there, just make sure protocol is originating one, NOT one supposed to be advertised.

Andy

Re: BGP advertise and prefix-list

melcu — Mon, 15 Sep 2025 19:42:27 GMT

But it's originating from a prefix list. They are not connected nor received from BGP or any other protocol.

Re: BGP advertise and prefix-list

the_rock — Mon, 15 Sep 2025 19:44:38 GMT

OK, so deleting line makes sense then 🙂

Andy

Re: BGP advertise and prefix-list

Chris_Atkinson — Tue, 16 Sep 2025 03:53:37 GMT

To clarify you are trying to advertise routes that arent in the local routing table / what are those IPs?

Need a little more info about this but sounds almost like a use case for the NAT Pools feature, don't let the name confuse.

Re: BGP advertise and prefix-list

the_rock — Mon, 15 Sep 2025 23:53:21 GMT

Hey Chris,

Since you mentioned nat pools, I thought that was related to routing, but only within VPN community. Or am I mistaken?

Andy

Re: BGP advertise and prefix-list

Chris_Atkinson — Tue, 16 Sep 2025 03:53:08 GMT

They are called NAT pools because that is a common use case (to advertise the NAT or VPN range) but it's not their exclusive purpose.

More generally in the absence of a route existing they provide an anchor mechanism for that network/subnet which can then be used in route advertisements / redistribution via route-maps etc.

Refer: https://sc1.checkpoint.com/documents/R81/WebAdminGuides/EN/CP_R81_Gaia_Advanced_Routing_AdminGuide/Topics-GARG/NAT-Pools.htm

Re: BGP advertise and prefix-list

the_rock — Tue, 16 Sep 2025 03:09:59 GMT

Got it, thank you!

Re: BGP advertise and prefix-list

melcu — Tue, 16 Sep 2025 06:28:10 GMT

Hmm I thought it will work like Cisco but indeed NAT-Pool may be the solution for this!
I'll keep you posted.

Re: BGP advertise and prefix-list

melcu — Tue, 16 Sep 2025 07:05:51 GMT

Indeed nat-pool was the solution.

Thank you Chris! Awesome as always!

Re: BGP advertise and prefix-list

the_rock — Tue, 16 Sep 2025 11:02:53 GMT

Amazing! Always learn something new from @Chris_Atkinson 🙌

Andy

Re: BGP advertise and prefix-list

Chris_Atkinson — Tue, 16 Sep 2025 11:34:11 GMT

Can't speak for what it's like on an FTD but usually for Cisco you need a network statement / anchor route (Null0) at least. Glad it's working for you now!

Re: BGP advertise and prefix-list

the_rock — Tue, 16 Sep 2025 11:46:01 GMT

I will ask one of my colleagues who is really good with Cisco, Im super curious now.

Andy

Re: BGP advertise and prefix-list

the_rock — Tue, 16 Sep 2025 11:52:01 GMT

Silly me...I totally confused this with IP pool nat feature in global properties in smart console. Im thinking, wait, this can NOT be the same thing haha

Andy