[nsp] OSPF Area Design

Chris Moore - GMD chris.moore at gmd.com
Thu Feb 26 08:37:14 EST 2004

FWIW, my network is almost exactly like Vandy's and I'm doing exactly as
suggested below and it seems to work pretty well.


------- Original Message --------
Message: 5
Date: Wed, 25 Feb 2004 22:56:35 -0500
From: "David Curran" <dm at nuvox.net>
Subject: RE: [nsp] OSPF Area Design
To: <cisco-nsp at puck.nether.net>
Content-Type: text/plain;	charset="iso-8859-1"

Is it too simplistic to say that with only 10 routers in your network and
not much chance for flap that all routers would be in Area 0?  I realize it
makes a pretty picture on a whiteboard to make each router its own area but
I'm not sure its necessary.  For example:

1.)  Each office with 'Net access has a static route to ISP pointed to the
1A.) Above router advertises default route as metric-type 1 using:
     'default-information originate metric-type 1'

2.)  Manually configure costs on each routers subinterface to reflect your
preference.  e.g. A Chicago to LA link is 'ip ospf cost 10000' and a Chicago
to St. Louis link would be 'ip ospf cost 5000'.

Its as simple as it gets.  2 lines under the ospf processes (ok, 3 if you
add no auto-cost) and 1 under the interface.  If there's chance for any real
growth (i.e. 20 or 30 routers in area 0) then maybe you should break it into
areas.  However, most stable (read 'no dial-up') networks can grow very
large in one area with no problems.

Just a thought ;-)

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