Kevin Dorrell, CCIE #20765

25 Feb 2008

NMC Lab 09 – The Golden Moment

Filed under: IP Addressing Services, OSPF, Redistribution — dorreke @ 23:48

It’s week 9, so I’m doing NMC Lab 09.  This time I think I have reach the full reachability as fast as I can: 2 hours and 20 minutes.  I was cautious – maybe over cautious – about the redistribution, only redistributing internal routes of each protocol.  (Except for RIP, which is out on a limb and therefore can be redistributed blindly.)  Of course, that left me with a lot of redistributing connected, but that was allowed by the scenario.

R4-Lo104 was the joker in the pack, because there were no instructions.  I redistributed it into both OSPF and EIGRP just for good measure.  I then looked at R3 and decided the 104 subnet would be better handled by EIGRP than OSPF.  In fact, if the R3 chooses the OSPF route to Lo104, then R6 never sees it.  So I punished every OSPF LSA coming from R4 with distance 180 172.16.104.1 0.0.0.0 at R3.  (The 172.16.104.1 being the router ID of R4 … it is only coincidence that it is also the subnet we are trying to manipulate.)  Probably would have been easier if I had just sent it into EIGRP and not to OSPF.

I suspect they wanted me to put the R2-R5 link into OSPF area 12, and use the R2-S1/0 address for the unnumbered reference on the Tunnel.  So just to be perverse, I didn’t do it that way.  Insead, I based my tunnel on R1-L101 and R2-L102, and I activated the OSPF on it with the interface command ip ospf 9 area 12.  That left me free to use whatever area I chose for the R2-R5 link.  I chose area 25, and made a string of virtual links across area 25 and area 51.

 There is something that makes me want to put a virtual link between R1 and R2 across area 12 to leverage that nice fast Ethernet segment rather than going through the Frame Relay.  I’ll bear that in mind if there is any RPF issue in the multicast.

More tomorrow.  The IPv6 and Cat 3560 sections look a bit heavy.  But it’s late now, the rest of the family are in bed already (one with ‘flu) and I need my sleep.

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