AT&T NYC

alex at yuriev.com alex at yuriev.com
Mon Sep 2 20:02:22 UTC 2002


> > > > > With link-state, one interface flap can mean doing SPF on every route.
> > > >
> > > > Only if you learned every one of your routes from different neighbor.
> > > > If you have two exits and 100000 routes, you calculate twice and
> > > > apply the results to the prefixes.
> > > >
> > > > Note that this does not apply to a proprietary, "hybrid", semi-link
> > > > state protocol marketed with name "EIGRP" where all routes need
> > > > per-prefix calculation. (OSPF and IS-IS work fine)
> 
> but.. with SPF you need to run the algorithm on all paths for each flap and then
> see what that does to your routes
> 
> with eigrp you only need to apply the algorithm to any route on the link that
> flapped and then only on the attached router (which will propogate much like bgp
> if it requires other routers to recalculate)
> 
> yes thats bad if yuo have 100000 routes but you shouldnt have! assuming a
> smaller routing table yuo get quicker convergence and much much less CPU
> requirement on your rotuers


And with nailed BGP routes you dont need additional layer of complexity.


Alex





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