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We are running an old Cisco 7200 VXR router as our border router and lately have had issues with sites failing to resolve. A manual BGP reset on this router resolves all of our problems.

I'm fearing memory corruption is the cause but I'm not entirely sure how to troubleshoot this, as I'm relatively inexperienced with his level of network hardware.

Could you help point out potential causes for the described problem, and point me towards a good resource for troubleshooting?

Thanks

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Could you provide some more detail in your question regarding the resources of the router and the number of routes it's receiving via BGP (plus any other protocols) - if you could also give the output of things like "show mem sum", "show ip bgp" and "show plat hard cap forw" that'd be great. –  Olipro May 12 '13 at 4:42
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1 Answer

Are you syslogging anything? When you are able to login to the router, try a show log and see what it says over the past day or so, there will probably be some pointers in there.

Why are you thinking memory corruption? Although routers are, when it comes down to it, computers with specialized hardware they have completely different failure modes.

Do all sites fail to resolve, or just some? Where is your primary DNS server, is it on this side of the router or the far side of the router?

Is this router doing NAT or other L4 processing, or is it just a straight L3 router?

A 'manual BGP reset' (clear ip bgp neighbor * or clear ip bgp * )? just flushes out all the routes (or all the neighbors) and makes it relearn them/bring them back up. This can really mask many other problems that are usually fairly easy to solve.

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Syslog - I'll check that. Name resolution - Only some sites fail to resolve. Primary DNS is on this side of the router. Router is doing NAT. –  Ryan May 6 '13 at 20:07
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