BGP and VRF configuration issue

Unanswered Question
Feb 27th, 2007

We are trying to use BGP and VRF on our border gateway.

We have two ISP (ISP1 ISP2) and a BGP session with each of them.

On the border gateway we have two VRF: each of them is associated

to a different local AS (AS1 AS2).

The BGP process defined on the border is BGP AS2 and we defined

two BGP session: the first with the AS-ISP1 and the second

with AS-ISP2.

router bgp AS2

no synchronization

bgp log-neighbor-changes

network x.y.0.0 mask 255.255.224.0

aggregate-address x.y.0.0 255.255.224.0

neighbor 193.206.128.137 remote-as AS-ISP1

neighbor 193.206.128.137 local-as AS1

neighbor 193.206.128.137 version 4

neighbor 213.140.31.108 remote-as AS-ISP2

neighbor 213.140.31.108 ebgp-multihop 255

neighbor 213.140.31.108 version 4

The problem is that the ISP2 correctly receives our announced

network with AS-Path: AS2

whereas ISP1 receives our announced network

with the AS-Path: AS1, AS2: we would instead the

AS-Path to be AS1.

We cannot use the replace-as feature because it is not supported

in our IOS release 12.2(18)SXF6. Is there any other way to do it ?

Thank you,

Alessandro Asson

I have this problem too.
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deilert Tue, 02/27/2007 - 09:16

Who is AS1? where are you picking up the AS from ?

can you paste in a sh ip bgp x.x.x.x

and a sh ip bgp nei 193.206.128.137 advertised

sh ip bgp nei 213.140.31.108 for that network

Harold Ritter Tue, 02/27/2007 - 13:27

Alessandro,

I do not see any other way to do this. The replace-as knob is available in 12.2(33)SRA though.

Hope this helps,

rebecca.richards Tue, 02/27/2007 - 19:59

hmm... If you want to be known to ISP1 as AS1, and ISP2 as AS2 (for whatever reason), wouldn't you be better off using BGP confederations?

cineca Wed, 02/28/2007 - 08:44

>hmm... If you want to be known to ISP1 as AS1, and ISP2 as AS2 (for whatever reason), wouldn't you be better off using BGP confederations?

We have two separate ASes: AS1 to be known to ISP1 as AS1 and AS2 to be known to ISP2 as AS2. They represent two routing domain that have to keep separate. With the confederation

on the contrary I understand that I can announce the two (or more) local AS as one.

Alessandro Asson

cineca Wed, 02/28/2007 - 08:12

Ok, thank you.

The problem is that 12.2(33)SRA seems not

to support VRF ligth..

Best Regards,

Alessandro Asson

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