From: Toh Soon, Lim (tohsoon28@gmail.com)
Date: Sun Sep 02 2007 - 11:25:08 ART
Hi Group,
I'd like to seek your opinion on how to correctly interpret and answer this
task. Scenario as follows:
-----area0-----(Fa0/0) R6 (s0/0/0)-----area40------(s0/0) R4
(Fa0/0)-----RIP-----(Fa0/0) BB1
Task: Configure area 40 so that it only has a default route with a cost of
4444 to reach all networks not attached to BB1.
One possible solution on R6:
!
router ospf 1
area 40 nssa no-summary
area 40 default-cost 4380
!
It got to be NSSA because R4 will redistribute RIP into OSPF. This config
blocks LSA Types 3-5 into Area 40 and R6 sources a Type 3 default route into
Area 40. Cost of s0/0 on R4 is 64. Setting default-cost to 4380 on R6 will
cause R4 to receive the default route with a metric of 4444. If we have more
routers in Area 40, we can't guarantee everyone gets a metric of 4444
because it will accumulate as it propagates in Area 40. So I don't think
this solution exactly answers the question. Or should I not be thinking too
much? As long as R4 sees 4444, that's it?
Second solution:
!
router ospf 1
area 40 nssa default-information-originate metric 4444
!
R6 will source an N2 default route into Area 40. Since it's N2, the default
metric 4444 will remain as it propagates in Area 40. This seems to answer
the question. But inter-area routes do leak into Area 40. In one sense, it
seems not to meet the requirement of "...so that it only has a default
route...".
Any opinions are welcome.
Thank you.
B.Rgds,
Lim TS
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