Consider the following topology:
area_0---ABR_1----area_1-----ABR_2----area_0
There are two area 0's. ABR_1 and ABR_2 will generate
type 3 summary LSAs for the respective area 0s and
flood the information into area_1. An internal
router in area 1 will see the summary LSAs from ABR_1
and ABR_2, determine the best routes, and then insert
them into it's routing table.
Now consider ABR_1. It sees and stores in it's area 1
LSDB the summary LSAs it got from ABR_2.
The OSPF spec indicates that ABR_1, however, should
not forward this routing information into it's own area 0
connection. This is done to prevent routing loops.
My question is this: What is the reason why ABR_1 can
not use the routing information learned via ABR_2's
summary LSA and install these routes into it's own
routing table?
Note, I believe if there was a virtual link between ABR_1
and 2, ABR_1 would learn via ABR_2 the same set of routes via
summary LSAs and would be allowed to enter them into it's
routing table.
There must be a routing loop issue here, but don't see
it.
Thanks
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=57990&t=57990
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