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

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L0 Member

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

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

Tags (3)
L7 Applicator

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

@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. 

L4 Transporter

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

@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

L7 Applicator

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

@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! 

L0 Member

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

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

L4 Transporter

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

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?

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