Re: [nsp] [nsp] OSPF NSSA redistribution

From: Kevin M. Woods (kev@nil.org)
Date: Thu Jun 01 2000 - 23:03:18 EDT


// Hi,
//
// the next NSSA question ;)
//
// Short: can I summarise to the backbone, but not summarise to the NSSA
// area?

Short answer; yes you can. The `summary-address' command has several uses
for OSPF, one of which will do what you want when used on a NSSA ABR
(summarizes Type-5s during their translation from Type-7s which were
learned from routers internal to the area).

// Long: Let's say there are two access servers, A and B. They share the
// same telco rotary for static IP address dialups, say from 10.0.0.0/24,
// so we need some routing protocol between them. Both A and B have
// backbone links to area 0.
//
// Now I want that:
//
// 1. both routers announce the summary 10.0.0.0/24 to area 0
//
// 2. both router announce the individual host routes like 10.0.0.1/32
// to each other.
//
// Is this possible?

It sounds like routers A and B are not only NSSA ABRs, but also ASBRs which
means the `summary-address' command will not do what you want (at least not
for the external routes originating from them because of what you described
below).

// Using the naive approach os "summary-address" does not work since in
// that case the routes are summarised to the NSSA area, too.
//
// I could of course run another routing protocol, say, EIGRP 2., but
// only if that's really necessary.
//
// Robert

Kevin



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