I have seen more than a handfull of books confusingly explain E1 vs. E2 routes........and unless this is a case of the blind leading the blind, I can't make sense of what they are trying to say. I have used OSPF for years, and on ASBR's I basically just leave it as the default type-2 external routes. But I think I have a handle on the difference between the two: E1 routes add the internal and external cost to a destination. E2 routes consider only the external cost to a destination. So, obvious to me, if you have an internal cost of 30 and an external cost of say 20, then the E1 cost will be 50 and the E2 cost would be 20. I would think that E2 would always be preferred to a destination (from the same source) over E1. But I see book after book say (and I quote): "OSPF type 1 routes are always preferred over type 2 routes for the same destination, because the cost will always be lower." Now if you have a E1 and E2 route with EQUAL costs, I know the E2 route will be preferred. But if anyone can make sense of the above sentence I would appreciate it. Like I said, to me it seems vivdly clear that E2 cost will always be less than E1 cost for a given destination, and therefore always preferred (for the same path). Let me say this now, the statement: "OSPF type 1 routes are preferred over type 2" routes, I can agree with. Because from a design perspective.......it would be preferrable (generally) to take into account both the internal and external cost of a route.........so i agree with that. But when book author reads into that further and then tacks onto the end of the sentence "....because the cost will always be lower." Then I think to myself a) either they don't understand what they read, or b) I don't understand what I think I know.........and it worries me :) Brian ----------------------------------------------- Brian Feeny, CCNP, CCDP [EMAIL PROTECTED] Network Administrator ShreveNet Inc. (ASN 11881) _________________________________ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
