topic Re: Are Multiple Virtual Routers needed for BGP peering with multiple local AS numbers? in General Topics

Are Multiple Virtual Routers needed for BGP peering with multiple local AS numbers?

Eusono — Tue, 24 Apr 2018 20:27:34 GMT

Hi everyone,

I have a situation where a location has 2 MPLS circuits. On one MPLS circuit, the local ASN is 65136. On the other, the local ASN is 7014. Is it possible to peer with both providers using the same Virtual router, or would I need to create a seperate Virtual Router for each circuit?

thanks!

/Evan

Re: Are Multiple Virtual Routers needed for BGP peering with multiple local AS numbers?

BPry — Wed, 25 Apr 2018 12:37:11 GMT

@Eusono,

Since you are utilizing multiple ASN then I belive the answer is yes, you'll need to configure two different virtual routers to actually get this to function correctly.

Re: Are Multiple Virtual Routers needed for BGP peering with multiple local AS numbers?

rmfalconer — Thu, 26 Apr 2018 15:53:43 GMT

@Eusono

You can actually use a single VR for peering with multiple BGP AS. We use BGP quite a bit with PAs and have one site where it peers with 3 other external AS numbers, 1 for MPLS, 1 for a P2P line and the third for a B2B partner.

Just make sure that you use appropriate import and export filters for each peer so that you don't advertise prefixes where you may not want them.

set network virtual-router VR1 protocol bgp peer-group P1 peer P1 peer-as 65488

set network virtual-router VR1 protocol bgp peer-group P2 peer P2 peer-as 64512

set network virtual-router VR1 protocol bgp peer-group P3 peer P3 peer-as 13979

Re: Are Multiple Virtual Routers needed for BGP peering with multiple local AS numbers?

BPry — Thu, 26 Apr 2018 16:00:57 GMT

@rmfalconer,

Thought it was odd that you couldn't use multiple different AS numbers, but I couldn't find any documentation on how. Thanks for the knowledge!

Re: Are Multiple Virtual Routers needed for BGP peering with multiple local AS numbers?

Eusono — Fri, 27 Apr 2018 20:58:48 GMT

This is a useful answer, but it's not really pertaining to the question (though I can see how it could have been mistaken).

I'm not confused on how to peer with a different AS. My concern is this...

MPLS-A MPLS-B
AS=2828 AS=3069

\ /

AS=65136 AS=7014

PAN

Re: Are Multiple Virtual Routers needed for BGP peering with multiple local AS numbers?

rmfalconer — Fri, 27 Apr 2018 21:19:36 GMT

Got it, your picture makes things clearer.

Typically devices can only run a single BGP process per virtual router/context/vrf. On a Cisco router, you can spoof your AS to a peer by using the 'local-as' command. But as far as I know, the PA doesn't have this option.

I think with your setup, you'll either need to change your AS number with one of the providers or use another virtual router for one of the peerings.

Will each MPLS network be advertising different prefixes or the same prefixes?