Joe, > The problem is that unless one is holding customer routes in a > seperate VRF and dampen them there or take similar steps to > segment, dampening leads directly to blackholes. Even in that > case, failover within that VRF wouldn't work, as all > implementations I've seen attack the prefix as the problem instead > of the path vector. Bye-bye alternate paths.
I guess what I'm hinting at is precisely something finer-grained (path not prefix), as you suggest. Per-neighbor enabled, versus "entire bgp RIB" would be preferred. I'm also interested in the *chronic* nature of these apparent instabilities. An average of one flap per minute could imply that the end-site is not getting allot of useful TCP moved, and as such, after something on the (n)-hour timescale, perhaps it's worth suppressing it. So, I'd ask for a long-timescale dampening function, indexed against per-path, and enforced per neighbor. Perhaps as-path lists could be combined with relaxed timers on existing implementations to achieve this today (in a VRF target/context). -Tk
