[c-nsp] OSPF VS ISIS

Oliver Boehmer (oboehmer) oboehmer at cisco.com
Mon Feb 27 09:13:56 EST 2006

Vincent De Keyzer <mailto:vincent at dekeyzer.net> wrote on Monday,
February 27, 2006 2:46 PM:

>> But in a properly designed network, both protocols
>> can converge in sub-second..
> My OSPF network is far from converging sub-second (so according to
> you it is far from being properly designed - fine, I can take
criticism :)
> First of all, link failure on Ethernet links takes 30 to 40 seconds to
> detect... is there anyway to speed this up?

BFD, or fast-hello's if you accept the caveats (false-negatives)

> Then, even after failure detection, I have the feeling it still takes
> 3 to 5 seconds to converge...
> What am I doing wrong?

did you tune any of your timers? You need to tune your throttle timers,
below is a pretty aggressive sample configuration:

timers throttle spf 50 20 5000
timers throttle lsa all 0 20 5000
timers lsa arrival 15
timers pacing flood 15

by default, SPF will not kick in until 5 seconds after a new LSA has


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