[c-nsp] Reasons for "random" ISIS flapping?

Mark Tinka mark.tinka at seacom.mu
Thu Aug 29 23:07:15 EDT 2013


On Friday, August 30, 2013 04:50:33 AM Pete Lumbis wrote:

> I don't know anything about Juniper, but in general LFA
> is just a step ahead at the protocol level. We do a
> second SPF run on the remainder of the routes after
> picking the best and install all those as backup paths.

Yes, LFA as designed.

> We still need something to trigger the switchover. The
> only thing I can think of is how you were simulating
> failure. Lost of carrier will always beat BFD.

Agree - carrier loss detection is faster than BFD, which is 
why we tried to simulate other failure types such as PFE 
(data plane) failure, differences in detection based on 
whether we pulled the cable or shutdown the port, failure of 
the link from the remote side, e.t.c.

Results varied from 20ms - 120ms without BFD, depending on 
how failure was done.

As is the case with labs, there is never enough time for all 
scenarios, so I'm going to put some personal work into this.

Mark.
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