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Single carrier multi-circuit asynchronous routing issue
From: Aaron Millisor <aaron.millisor () bright net>
Date: Wed, 07 Jan 2009 14:53:25 -0500

I am curious to know if anyone has else has hit a problem like the one I am running into right now.

I have two DS3 DIA's in my router, terminating on two separate routers at Sprint. We peer with BGP and I am prepending certain of my prefixes to balance the traffic load.

src                      __________                dst
1.1.1.0 |----|- ds3 #1 -| sprint 1 |--(          ) 2.2.2.0
------- |me  |                        ( internet ) -------
        |    |                        (          )
        |    |           __________   (          )
        |----|- ds3 #2 -| sprint 2 |--(          )


If I were to prepend the network 1.1.1.0 to come in on 'sprint 1', but have a route to 2.2.2.0 via 'sprint 2' so that traffic comes in on one circuit but returns on the other, routing is broken. If I change my route so that packets directed to 2.2.2.0 return on the same circuit that the traffic is received on, everything works fine.

Has anyone else run into an issue like this before?


-- am



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