Does anybody have a reference to the real best path selection process actually used by an M7i running 9.3 that documents all of the tie-breaking criteria, and when it might decide to just blow off recomputing a new best route if the important attributes didn't change?
I was poking around today on a router that is excepting 2 identical iBGP feeds of routes to black hole. Approximately 70% of the routes from 1 server were marked as best and 30% from the other. The published selection algorithm docs only include deterministic criteria, and so I would have expected deterministic results and that the routes from the black-hole server with the lowest router ID would be preferred 100% of the time. http://www.juniper.net/techpubs/en_US/junos/information-products/topic-collections/nog-baseline/topic-20357.html The underlying system feeding routes to the 2 black hole servers guarantees that both servers are sending identical lists of prefixes, with identical local-pref, as-path, origin code, med value, source protocol, etc. The import policy explicitly sets the next-hop to discard for all routes from both servers so IGP distance shouldn't be a factor. The only differences between the routes announced from each black hole server visible in show route extensive are router ID, Task, and the time that the route was announced. It appears that it is showing the oldest route as the 'best' one. This isn't causing me any trouble, but it looks wrong, and making routing decisions based on age has bit me in the past. :-( Joe Metzger [email protected] _______________________________________________ juniper-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/juniper-nsp
