[c-nsp] OSPF NSSA Question

Dan Armstrong dan at beanfield.com
Sun Oct 3 18:10:43 EDT 2004

I am tearing my hair out here with an NSSA problem, any help is appreciated:

Say I have a distribution layer router, that is connected to it's backbone 
with OSPF in area 0.

I have a whack-O-Access routers, each access router in a different VLAN, 
connecting to a different interface on the distribution layer router.

Customer's IP blocks get anchored on the access routers, and my purpose for 
using a routing protocol here is to get the IP blocks (which are C routes on 
the access routers)  advertised up into the dist router, and on up into the 

The only way anything can leave the access router is via the distribution 
router, so I decided to make a stub area (nssa actually) for all the access 
routers.  The access router only needs a default advertised, and life is 

For some reason, I am missing, OSPF is advertising every little stupid block 
on every access router to every other access router, via the distribution 
router.  All I need is the default route, why does OSPF insist on advertising 
all these blocks?  Isn't the whole point of a stub area to be able to prevent 
a million specific prefixes from being advertised into it and add a simple 
default route if a router only has 1 exit point?

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