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Webcast-Catalyst9k
New Member

BGP routing question

We have two router facing 2 isp router.

1st. router is using static route. (we are currently using this in/out traffic, and we are planning to change it to BGP)

2nd router is setup to do BGP

Downstream firewall is pointing to the first router.

Last night I receive an alert that traffic path was going to 2nd ISPs path (based on traceroute)

.

From the 1st router, I was able to hit outside, but not from the firewall or any downstream devices.

I had to shut down the interface on 2nd router to stop the traffic head the router.

In minutes all traffic was going through 1st router.

Can anyone explain why this would happen ?

Could this be ISP's screw up ? (maybe accidently reannouncing the prefer path by 2nd isp's end )

Help!!!

1 REPLY
New Member

Re: BGP routing question

I think no one can pin point the cause of problem for you because we need more information ex. network diagram, how you exchange routing with both ISPs, IP address you using & who own those IP, ..., etc. How about the reachability from your FW to both routers?

From the information you gave us, 1st router & 1st ISP network was working properly because you can go outside by using their IP address on serial line as source IP.

The cause of problem may come from your routing policy setting up by both ISPs. Since you do not run BGP to exchange routing with both ISPs, it is very difficult to identify the problem

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