On 26 Jul 2006, at 08:29, Forrest W Christian wrote:
I don't have an answer to the root cause of your problem, and I'm not looking for a discussion on route dampening (there are enough debates onthis issue to make your head spin), but may I suggest you raise your hold timers to prevent your BGP sessions from going down on short disturbances as these? From what I can tell the disturbances are less than a second in duration. It doesn't appear that this is a hold-timer issue, although I would like GX to set it at something higher than 90 seconds (mine is already at a higher value- but the lower value wins during negotiation). I really suspect that either a) GX has some semi-weird configuration where the SONET ring switching from
Randy Epstein wrote: the normal to the protect path and back causes BGP to reset on the border router I'm attached to or b) There is a separate issue which is causing BGP to flap. Or of course, something else completely different.
Unfortunately, I haven't been able to figure out how to talk to anyone at GX which actually has access to the routers and knows anything about BGP. -forrest
The timing of protection switching on a SONET ring is of completely the wrong order to upset a BGP session. From memory there's a designed in upper bound of 200 mS from fault to fully restored with typical values being more like 50 mS. One possibility that occurs to me is that the A end here might be using a router with a SONET card, and the router software is propagating a SONET event through the stack causing BGP to react to an event it wouldn't even see on a physically separate SONET ADM. That is pure speculation though.