On Tue, Oct 27, 2009 at 10:00:07PM +0100, Martin Kraus wrote:
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.
Really, in the case of a tie, shorter way will be used. I omitted this case for simplicity. There is a simple explanation: consider there is just one metric, which is a triple (K, M2, M1), where K is a kind of a route (0 for I, 1 for E1, 2 for E2), M2 is ospf_metric2 for E2, zero for others and M1 is ospf_metric1. Then the route with smaller triple is preferred (the triples are lexicographically ordered).
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.
If external route is exported to OSPF, you can set ospf_metric1 or ospf_metric2 using filters. If just ospf_metric1 is set, route becomes E1. If just ospf_metric2 is set, route becomes E2. If nothing is set, E2 with ospf_metric2 = 10000 is the default. If both are set (uninteresting corner case), ospf_metric2 is ignored. -- Elen sila lumenn' omentielvo Ondrej 'SanTiago' Zajicek (email: santiago@crfreenet.org) OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) "To err is human -- to blame it on a computer is even more so."