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Routing problem


From: Arturo Lev Servin Niembro <aservin () campus mty itesm mx>
Date: Fri, 10 May 2002 17:07:25 -0500

Hi,

I have a strange question because this is not very common. Lets asume the following scenario to simplify it:


net A -- RTA --- RT1-ISP1 --- IP Cloud --- RT2-ISP1 -- RTB -- net b
--- RT1-ISP2 --- IP cloud --- RT2-ISP2 --


RTA and RTB are in differents ASs. ISP1 is preferred via BGP (local preference). Sometimes we lost reachability between net A and net B but we can stiil see the routes trough ISP1, so the BGP can not converge to ISP2. The problem is because the ISP1 have troubles with their IP-MPLS network, so, sometime they lost traffic.

Do you now about some trick that can be used to know that the path to net b is not good despite the route is still in RTA?

I was thinking to force the loopback from ISP1 to be learned in RTA to some route learned from RTB, but how. I think that if I make a tunnel interface it would still depend from BGP to work and BGP depend form tunnel, so it would not work.

Any idea that do not imply to change ISP1 nor use ISP2 as default?

Thanks in Advance,
-as


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