topic Re: Cisco FTD - BGP two instance (two different AS Number) in Network Security

Cisco FTD - BGP two instance (two different AS Number)

mikiNet — Fri, 06 Feb 2026 09:39:03 GMT

Dear Team,

I have a problem related to BGP configuration. I have below topology:

I want to run two BGP instance (two AS number on FTD):

1. BGP AS 49001, where FTD will establish iBGP with upper router

2. BGP AS 65001, where FTD will establish eBGP with down router (his AS 65002)

But I don't see any possiblity to run two BGP on FTD. On General Setting I have only option to put ONE AS Number...

Also when I create VRF, I still option to use ONE AS..

Is it possible to run two AS on same FTD ?

Re: Cisco FTD - BGP two instance (two different AS Number)

M02@rt37 — Fri, 06 Feb 2026 10:12:31 GMT

Hello @mikiNet

ASN with network equipment ? Firewall_routers => Only one AS possible ! You cannot run multiple local ASNs as the same time in one BGP process. Some network equipment permit with the command "local-as" to established bgp session with neighbor with a "fake" asn...

Re: Cisco FTD - BGP two instance (two different AS Number)

Cristian Matei — Fri, 06 Feb 2026 16:41:07 GMT

Hi,

@mikiNet Don't overcomplicate it using a VRF / separate Virtual Router. Recommend to run BGP in AS 49001 too establish iBGP upstream and for eBGP peering downstream use local-as functionality when configuring the eBGP neighbor (found under Migration tab). To ensure you can advertise BGP best-paths between your eBGP and iBGP neighbors, and these will not reject the updates due to AS loop prevention, when using local-as functionality, ensure to check minimum the first two knobs as well (Do not prepend local AS, Replace Real AS).

Thanks,

Cristian.