Routing over T1 with backup BGP & Static

Unanswered Question
Oct 26th, 2009

Hi all, complex problem here, and probably has a simple solution. I have a site connected to an MPLS network, a single T1, and a wireless connection, 2 routers, for the CPE, and one PE. The trick here is to route all 10.x.x.x addresses over the T1, and all internet traffic over the wireless. Simple enough with static routes, but the circuits need to back each other up. Using BGP I can prefer one circuit for the 10.0.0.0 and static the default, but how do I backup the default to use the other circuit when the default connection is down. Or reverse it, BGP the default, and static the 10.0.0.0/8. If the T1 goes down I want the traffic to fail over to the wireless automatically. If the Wireless goes down, I want the default to use the T1. The latter I can get to work, but the T1 failure, since static, I am having troubles with. How can I setup a weighted static to use the other router if the T1 fails? Or how can I setup BGP to prefer the t1 over the wireless, unless it drops?

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Jerry Ye Mon, 10/26/2009 - 10:21

You can do this with static routes


ip route 10.0.0.0 255.0.0.0 a.a.a.a

ip route 0.0.0.0 0.0.0.0 b.b.b.b

ip route 10.0.0.0 255.0.0.0 b.b.b.b 150

ip route 0.0.0.0 0.0.0.0 a.a.a.a 150


The trick is set up two (2) static route for the same network and point it to different next-hop where one has a higher admin distance then the other.


If you want to mix BGP with static, you can do something like this, just make sure the prefix lenght is the same but one has higher admin distance the other.


Regards,

jerry

tahequivoice Tue, 10/27/2009 - 07:09

Well 2 hours of programming and I got it to work using a combination of iBGP, eBGP and Weighted Static routing, and failover actually works as I planned. The problem that took the longest was each router was preferring itself for default until I added a weight to the i neighbor and bingo, that did it.

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