[c-nsp] OSPF NSSA Question

[Enno Rey]

Hi,

On Sun, Oct 03, 2004 at 06:10:43PM -0400, Dan Armstrong wrote:
> 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 
> backbone.  
> 
> 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 
> good.
> 
> 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?

correct, but an NSSA will still receive type 3 LSAs, means Inter-Area routes.
what you're trying to accomplish is done via a totally stub area.
see 
http://www.cisco.com/en/US/tech/tk365/tk480/technologies_tech_note09186a0080094aaa.shtml#areas

thanks,

Enno

 





> 
> 
> 
> 
> 
> 
> 
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/

-- 
Enno Rey

ERNW Enno Rey Netzwerke GmbH - Zaehringerstr. 46 - 69115 Heidelberg
Tel. +49 6221 480390 - Fax 6221 419008 - Mobil +49 173 6745902
www.ernw.de - PGP 055F B3F3 FE9D 71DD C0D5  444E C611 033E 3296 1CC1