"Stephen J. Wilcox" wrote:
>
>
> >
> > > 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
Steve
"Stephen J. Wilcox" wrote:
but.. with SPF you need to run the algorithm on all paths for each flap and then
see what that does to your routes
Only the paths that cross the one you lost. Obviously if this happens
or not, depends on your implementation. Look in the documentation under
heading "partial SPF".
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)
For this you need to look under the heading "non-technical marketing propaganda".
So far, I've yet to figure out a real life network example where
EIGRP would outperform either OSPF or IS-IS. Obviously if you compare
an ancient OSPF implementation to a more recent implementation of another
protocol, differences in performance can be found. Objective measurements
are hard to come by.
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
Most networks have more routes than they have links or routers. This already
by the nature that most links have one route. So the assumption that
number of routes would be small is usually incorrect. Obviously if you're talking
about <50 routes, choice of routing protocol does not make a difference and you'd
be probably happy running RIPv2.
Pete
> > > > 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