how to set priority of routers in ospf

Martin Kraus martin.kraus at wujiman.net
Tue Oct 27 22:00:07 CET 2009


On Tue, Oct 27, 2009 at 09:17:23PM +0100, Ondrej Zajicek wrote:
> If external route has defined valid ospf_metric2 metric, it is Type 2 external route
> (flag E2 in 'show route'), if not, it is Type 1 external route
> (flag E1 in 'show route'). Replace 'use Type X metric' with
> 'is a Type X external route' in mentioned rules.
> 
> Field ospf_metric1 is defined in all OSPF route types and contains contains
> IGP metric (+ possibly initial value of Type 1 metric for type 1 external
> routes)
> 
> > Both routes have type 1 metric 100 and one of them has type 2 10000 and the
> > other has 10500. 
> > ..
> > If I have two external routes, first with type1 = 1 and type2 = 100 and the
> > other one with type1 = 5 and type2 = 50 (as is show by show route all),
> > which will be used? 
> 
> In both cases they are Type 2 external routes and are compared according
> to ospf_metric2.

Thanks for the explanation. So if I've got two E2 routes with the same type 2
metric to the same destination several hops away from a given router to which 
there are two ways, it doesn't mean the shorter way will be used based on type
1 metric. 
One (hopefuly) final question. How does bird determine what route to designate
as E1? All I've got from bird are either E2 or Internal routes.

thanks again
mk



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