I explained the selection of FA in the blog that deals with Type 7 LSAs. You may want to check it out :-). Read the comments, too - there was a follow-up discussion and clarification there, where some of my assumptions were challenged.
In short: it really doesn't matter which address is used, as long as it's in OSPF. -- Marko Milivojevic - CCIE #18427 Senior Technical Instructor - IPexpert FREE CCIE training: http://bit.ly/vLecture Mailto: [email protected] Telephone: +1.810.326.1444 Web: http://www.ipexpert.com/ On Wed, Dec 8, 2010 at 13:54, Bojan Zivancevic <[email protected]> wrote: > Hi guys, > > > > recently I asked the question about what has priority in which IOS version, > regarding external OSPF routes. Will we prefer ‘N’ or ‘E’ routes, if they > are of the same type and the same metric. There was a dispute about which > RFC some IOSes conform to etc... Tyson said that the good guess is 12.4(15)T > so I decided to try this IOS and see what happens. > > > > This is all on dynamips, so maybe it influenced some peculiar events, but > somehow I doubt it. > > The topology is like this: > > - R2 is the “hub” where everybody connects, there are three areas > 0,1 and 3 > > - R1 is in standard area 1, redistributing 1.1.1.1 network > > - R3 is in NSSA area 3, redistributing also 1.1.1.1 network > > - R4 is in area 0, on the “other side” of R2 when looking from the > point of R1 and R3 > > > > So, R2 sees both paths to 1.1.1.1, one through R1 and the other through R3 > (nssa). R4 sees converted LSA-7 to LSA-5. > > > > 1. R2 preferred ‘E’ route over ‘N’ route. One dilemma solved, with > this IOS at least. Of course, when we have ‘N1’ route and ‘E2’ route, ‘N1’ > is preferred. > > 2. I noticed incosistency when it comes to forward address field. I > know it should contain the IP address of the ASBR. But sometimes I get the > IP of the R3 (ASBR) LAN interface connecting R2 and R3, and sometimes I get > the loopback interface IP on the ASBR. I can’t catch why it is changing and > when. Anybody has the idea? Why would OSPF ever put loopback IP in there? > > > > Best Regards, > > > > Bojan Zivancevic > > Network Engineer > > ---- > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
