BGP Over MPLS with Backup

Unanswered Question
Nov 8th, 2009


What considerations should be kept in mind when using BGP as the PE-CE Protocol.

I have a simple setup with a Main Site Connecting Regional Offices using MPLS as Primary and DXX (Leased line) as Backup.

I think I can modify the AS-Path to make the MPLS Cloud Primary and DXX as Backup

Any other thing I need to take care of ?



I have this problem too.
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Giuseppe Larosa Sun, 11/08/2009 - 04:45

Hello Zeeshan,

first thing to look at:

you should have eBGP sessions on the MPLS L3 VPN service

what type of BGP sessions are going to run on backup?

iBGP sessions or eBGP sessions?

are the primary BGP session and the secondary BGP session configured on a single node or in two different routers?

if it is a single node and backup session is iBGP you should be fine with default settings because eBGP paths are preferred over iBGP paths.

if the two sessions are configured on two different nodes you need to increase local preference on device that terminates the primary eBGP session to have second node to prefer it over the secondary iBGP session.

Hope to help


nishantmj Sun, 11/08/2009 - 04:49

Hi Zeeshan

In your case if you have MPLS bases link BGP neighborship will be with external AS , whereas for Leased link which you want to use as backup BGP neighbourship will be iBGP. In this case BGP will always choose the eBGP routes over iBGP routes. So, in your case u need not Modify anything.



Have nice day!


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