[j-nsp] Debugging excessive OSPF SPF runs

[Jee Kay]

We're currently trying to track down a problem where all of our
routers seem to be doing full SPF runs extremely frequently (on the
scale of once every 10-20 seconds). Aside from everything else, the
network seems stable (nothing is dropping off).

The main symptom we're seeing is that there are occasionally split
seconds when routes become unavailable; traceoptions SPF seems to
suggest that every so often the SPF runs and declares almost every
single route it comes across as the best route.

Does anyone have any recommendations for tracking this down? The
Junipers involved are all M5/M7is runing 7.4R3.4 and there are various
incarnations of Cisco and Netscreens (5.3r4.0) involved too... my
current suspicion centers heavily on the Netscreens doing something
bogus but I can't figure out how to build up some evidence :)

Thanks in advance,
Ras