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Flapping prefixes and dialup networks. Discuss.
Hi. I sent a network provider (who shall remain protected by a pseudonym like "AS 174") a brief note stating that they had a prefix that was flapping rather heavily throughout the day. I cut and pasted a show ip bgp on the route, pointing out that the prefix flaps on the order of once a minute and was happily being dampened. (cf. my comments Monday afternoon on dampening). BGP routing table entry for 18.104.22.168 255.255.255.0, version 656911 Paths: (2 available, no best path) 1239 174 (history entry) 22.214.171.124 (metric 15) from 126.96.36.199 (188.8.131.52) Origin IGP, metric 1, localpref 90, external Dampinfo: penalty 2915, flapped 199 times in 3:27:31 1239 174 (history entry) 184.108.40.206 (metric 15) from 220.127.116.11 (18.104.22.168) Origin IGP, metric 1, localpref 90, external Dampinfo: penalty 2917, flapped 198 times in 3:27:07 I also asked this nameless service provider to kindly check into this somewhat excessive amount of flap with a view to seeing how it could be made to flap less. Here was the reply. Hopefully saner and more patient folks than me might point out to service provider X that announcing to the entire world when a dialup user comes and goes is not healthy for the Internet, and it shouldn't happen, particularly not at this rate. Why I am not quite in the, "it doesn't matter, they'll be dampened" frame of mind will get explained during the NANOG session. Sean. - -- >From [email protected] Sun Sep 10 18:12:58 1995 From: PSI NISC <[email protected]> To: Sean Doran <[email protected]> Subject: nisc-03292 (ticket update) badly flapping prefix (204.4.27/24) Ticket #nisc-03292 09/10/95-18:12:08 silvera SUBJECT: badly flapping prefix (204.4.27/24) Posted by: Aaron Silver ---------- Sean, The customer that this network belongs to is a dial-up customer, and as such, when his connection is up, we broadcast his network IP, and stop broadcasting when he disables his connection. We are unable to prevent his route from propagating in the face of what could be frequent log-in/log-outs. Aaron Silver PSI Customer Support