BGP session with an ISP, but two seperate circuits

[DavidGIP]

Hello,

We currently have a BGP session established in our ASR9600 with an ISP over a 10G transport circuit. We are turning up a second 10G circuit with the same ISP. I know we can set up a LAG with the two circuits, but is it possible to just set up a second BGP session with a different IP to the same ISP? Or add the second IP to the existing session? Since it will terminate to the same equipment on both ends, my thought is that it will act like a LAG connection, but because they are two BGP separate links are a little more customizable. 

[Joseph W. Doherty]

". . . is it possible to just set up a second BGP session with a different IP to the same ISP?"

Yes.

"Or add the second IP to the existing session?"

Possibly not as what you may have in mind.

You could eBGP (Cisco's multihop) peer between a loopback on each router and (sort of) have LAG like behavior.

[Harold Ritter · Accepted solution]

Hi @DavidGIP ,

As @Joseph W. Doherty mentioned, it is certainly possible to configure two BGP neighbors between the same two routers. By default, BGP selects one of the two paths (via neighbor 1 or neighbor 2) as the best path and installs it in the RIB.

You will need to enable maximum-paths for your ASR9006 to install both paths in the RIB. This way you will be able to load balance between both links for Internet access. Otherwise, one of the links would be used only if the link considered as the primary path is unavailable.

router bgp xxx

address-family ipv4 unicast
maximum-paths ebgp 2

The same needs to be done on the ISP router.

Regards,