[c-nsp] OSPF area design question

[Tantsura, Jeff]

It sounds like you have backbone area of 3 routers and 3 area's of 15
routers interconnected by these 3.
15 routers per area will do just fine.
Good IP plan is much more important than # of routers.
Take care of summarization.
Remember that all communications between non backbone routers within
different areas go via backbone.
Make your spokes totally stubby.
Keep your backbone area as stable and simple as possible.

Jeff

P.S. Cisco recommends EIGRP for a hub-and-spoke network

With kind regards/ met vriendelijke groeten,
--------------------------------------------------------
Jeff Tantsura
CCIE #11416
Senior Consultant
Capgemini Nederland BV
Tel: +31(0)30 689 2866
Mob:+31(0)6 4588 6858
Fax: +31(0)30 689 6565
--------------------------------------------------------


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Marcel Lammerse
Sent: Monday, August 30, 2004 5:55 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] OSPF area design question

Hi,

I have a hub-and-spoke network, for which I'd like to use OSPF as a
routing protocol. The spoke sites will advertise their networks to the
hub and receive a default route from the hub.

A common piece of advice in OSPF design literature, is to use different
area numbers to prevent unnecessary LSA updates from flooding to routers
that don't need the updates and to avoid the cpu processing overhead.

The total network has some 50 routers.  There are 3 inter-connected hubs
and some 15 routers per hub. The way I see it, I can do two things:


1. 	assign a lot of area numbers to prevent the LSAs from
propagating
	through to routers that don't need them. However, this leads to
a
	relatively complex configuration.

2.	accept the, potentially small, bandwidth waste and don't care
	about the cpu overhead (we're talking 2600XMs here).

Option 1 just doesn't seem worth it. Could someone provide some advice,
experience or tips?

Thanks.

-Marcel

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