[c-nsp] OSPF area design question

[Mark Borchers]

Well, the level of effort in configuration would be about
the same if you only ran OSPF among the three hub routers
(area 0) and just static routed to the spokes, with redistribute-static
turned on (depending of course on how many static routes each
spoke would require).

 
> Ok, if you have that area 1 with 15 routers. Would it be a 
> good idea to 
> keep them all in one area, or would it make sense to assign 15 
> different area numbers and make each of them a separate area (NSSA in 
> this case). Because, I figured, an update from one of the router will 
> be flooded throughout the entire area which is totally unnecessary.
> 
> I like to know whether the extra configuration and administrative 
> overhead is worth saving on unnecessary update floods and cpu cycles 
> processing them.
> 
> On Aug 30, 2004, at 9:47 PM, James Hampton wrote:
> 
> > The way I'm reading this is that you have three hub routers 
> connected
> > like  points on a triangle, with each point having 15 or so 
> spokes? If
> > this is the case I would make the top router(or the one in 
> the middle)
> > area 0 and the others 1 and 2 or what ever numbering scheme you come
> > up with. Than address each area with contiguous blocks so 
> that you can
> > summarize and keep the routing table as small as possible. 
> The spokes
> > could be "stubby" sense they have only one way out.
> >
> > James
> >
> >
> > On Mon, 30 Aug 2004 17:54:35 +0200 (CEST), Marcel Lammerse
> > <lammerse at xs4all.nl> wrote:
> >> 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
> >>
> >> _______________________________________________
> >> 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/
> >>
> >
> >
> ---
> "..the price to pay for teenage sex is pretty high--
> unwanted pregnancy, disease, and ending up with one ear
> bigger than the rest because it's always cocked toward
> the door in case the parents come home early."
> 								
> 		- Michael Moore
> 
> _______________________________________________
> 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/
>