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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Flapping /16 prefix, why?
Sorry for littering NANOG with this email, but I'm hoping for a little
education on this matter from some of the larger National Service
Providers.
This morning we had a customer call in concerning a network hole.
Upon investigation, I found the following..
BGP routing table entry for 166.82.0.0/16, version 541808
Paths: (1 available, best #1, advertised over IBGP, EBGP)
1793 1239 1790 3505 3505
144.228.159.17 from 144.228.159.17 (144.228.159.1)
Origin IGP, metric 0, valid, external, best
Community: 1
Dampinfo: penalty 656, flapped 18 times in 02:19:29
Two immediate things came to mind here.
1. This is a /16 that is flapping.
2. The end user is using AS path prepending for some reason.
With these two facts in mind, the following questions arise.
Anchoring or tying down of a route with a static route to null seems
to be a very basic idea (far more basic that AS path prepending), so
why isn't this route tied down?
I only see one route to this prefix, why are they prepending? (I admit
that only the user of this prefix can answer this question, and I also
admit that with 53 flaps on the books so far, the other provider may
be dampening the route for us *thank you*)
Finally, does Sprint not apply *any* dampening to customer routes?
My cat is long dead (10 years at least), so it's safe from my curiosity.
Chris A. Icide
Nap.Net, L.L.C.
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