First off, in researching the answers here, I found an error in my blog :P I am referencing RFC 3103 and in fact that has nothing to do with OSPF : ) It should be RFC 3101 for the extra curious.
1) You are probably seeing two N2 routes because you have equal cost load balancing going on. In my lab I did not, and I made a point of saying that. Check out the output in the blog from "sh ip ospf border". In my lab I manually changed the cost of one of the links. 2) When the NSSA ABR gets two type-7 LSAs, the forwarding address set for the translated type-5 should be as follows from RFC 3101. Note, this tie breaker only happens IF the metrics, etc are the same. If everything is equal it seems it should come down to the one with the highest RID. Then again, some things in RFCs don't ALWAYS work out as they should on real routers :P If two NSSA routers, both > reachable from one another over the NSSA, originate functionally > equivalent Type-7 LSAs (i.e., same destination, cost and non-zero > forwarding address), then the router having the least preferred LSA > should flush its LSA. (See [OSPF] Section 12.4.4.1.) Preference > between two Type-7 LSAs is determined by the following tie breaker > rules: > > 1. An LSA with the P-bit set is preferred over one with the P-bit > clear. > > 2. If the P-bit settings are the same, the LSA with the higher > router ID is preferred. > > On Tue, Nov 17, 2009 at 1:35 PM, <[email protected]> wrote: > I am still digesting that blog. The issues you bring up along with the > poster on the blog are relevant to what I'm seeing as well. > > Waiting to hear more ;) > -nick > Sent from my Verizon Wireless BlackBerry > > -----Original Message----- > From: Kim Pedersen <[email protected]> > Date: Tue, 17 Nov 2009 18:47:21 > To: OSL CCIE Routing and Switching Lab Exam<[email protected]> > Subject: [OSL | CCIE_RS] OSPF Type-4 LSA & The Forward-Address Part 2 > issues. > > _______________________________________________ > 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 > -- Regards, Joe Astorino CCIE #24347 (R&S) Sr. Technical Instructor - IPexpert Mailto: [email protected] Telephone: +1.810.326.1444 Live Assistance, Please visit: www.ipexpert.com/chat eFax: +1.810.454.0130 IPexpert is a premier provider of Classroom and Self-Study Cisco CCNA (R&S, Voice & Security), CCNP, CCVP, CCSP and CCIE (R&S, Voice, Security & Service Provider) Certification Training with locations throughout the United States, Europe and Australia. Be sure to check out our online communities at www.ipexpert.com/communities and our public website at www.ipexpert.com
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