"Oliver Boehmer (oboehmer)" <[email protected]> wrote on 22/06/2009 01:47:27 a.m.:
> RE: [c-nsp] OSPF LSA timers > Oliver Boehmer (oboehmer) > to: Raymond Lucas, cisco-nsp > 22/06/2009 01:47 a.m. > > Raymond Lucas <> wrote on Tuesday, June 02, 2009 08:10: > > > Hi, > > > > I have been gradually rolling out OSPF across a network including the > > following bit of config: > > > > router ospf 172 > > ispf > > timers throttle lsa all 10 100 5000 > > timers lsa arrival 80 > > > > Which was fine until I arrived at a couple of 6506s with SUP2/MSFC2 > > running 12.2(17d)SXB9 which don't support those commands. Seems they > were > > only introduced in 12.2(18)SXF according to Software Advisor. > > > > We can't upgrade to 12.2(18)SXF due to a lack of memory on the switch > > processors. I'm not too worried by the "ispf" business, but I have a > > bad feeling about having a couple of devices different from their > > neighbours with the LSA stuff. To really up the nerves, these 6506s > > are are part of the core. I can imagine it working well most of the > > time but then failing badly when the pressure is on. > > > > So I guess my questions are: > > > > - Am I right to be worried, or will things work fine if I miss these > > commands from these devices? > > It'll work most of the time, until you run into situation where you need > to issue more than one LSA update per second (for the very same LSA id). > As the other devices will ignore the 2nd LSA update, you'll have to > retransmit and convergence will be delayed. Yeah, did some testing and figured the same thing myself. My local SE provided similar feedback and also a hidden command that would stop these devices ignoring those 2nd LSA updates. I would rather not use hidden commands if I can help it though. > > - Since these timers can only be set on a per device basis, as > > opposed to per interface, is there an elegant way to deal with this > > scenario? Obviously I would not be keen to remove the modified timers > > from the rest of the network! > > Well, if you really need these timers to meet your convergence targets, > you're out of luck and need to upgrade the devices. I would argue, > however, that you'll be able to get away with less aggressive LSA update > timers (i.e. timers throttle lsa update 10 1000 5000) in most scenarios. > Tuning SPF timers is usually more important.. Nice to know. In this particular scenario, it is currently not so important to have quick convergence in Area 0 where we have this problem. We don't have the problem in other areas which is important to us. Thanks heaps for the feedback, Ray _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
