Guys,
lets see how my ospf is going ......
in this design goal i would have thought you would have done this ....
hub and spoke....at the hub you have say 1 router (3620) with one interface
and 20 sub-interfaces.......
you also have 20 totally stubby area`s which connect into the hub...
config each stub as area 1 through 20
setup each sub int as per area`s 1-20
then setup the lan int as area 0
this way you have one router (hub) which is in area 0 and all the other
area`s aswell........
problem solved ????..
something tells me i`ve just either
A got it right and am a genius
B completely missed the point and broken every rule of ospf
YOU DECIDE
steve
>From: "Chuck Larrieu"
>Reply-To: "Chuck Larrieu"
>To: [EMAIL PROTECTED]
>Subject: RE: OSPF Hub and Spoke [7:9268]
>Date: Fri, 22 Jun 2001 01:15:31 -0400
>
>John, this one's got me to thinking a little bit. Your kinda right but
>kinda
>wrong.
>
>The areas are an OSPF structure, used for the building of the SPF tables.
>It's not that inter area traffic has to go through a discreet area 0, but
>that in OSPF in order for an area to learn about routes to another area
>there has to be an area 0 router in between them. It does not matter if
>there are a number of interfaces that are ABR's, or if there is a discrete
>and pure area 0.
>
>With OSPF, all that matters is that the appropriate adjacencies are formed,
>and that the LSA's are processed and that the OSPF database is created. If
>all that occurs, OSPF routes will be placed into the routing tables. As far
>as the router itself is concerned, routing is independent of the routing
>protocols involved.
>
>I've fooled with this in the past. I'll have to do another Q&D lab to
>gather
>some evidence, and post it here over the weekend.
>
>In the meantime, for those interested in some in-depth discussion of
>routing, Howard's white paper on Certification Zone is definitely worth
>reading. I have not seen the likes of it in any other source, including
>Doyle ( although it has been too long since I've read Doyle )
>
>Chuck
>
>
>-----Original Message-----
>From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of
>John
>Neiberger
>Sent: Thursday, June 21, 2001 6:55 AM
>To: [EMAIL PROTECTED]
>Subject: Re: OSPF Hub and Spoke [7:9268]
>
>Yes, I'm replying to myself.
>
>While doing some reading it occurred to me why *not* extending area 0
>across
>the WAN links should not work. In OSPF, unlike IS-IS, an area is defined
>by
>links, not routers. The rule states that interarea traffic must go through
>area 0. Well, if areas are defined by links, then this means that
>interarea
>traffic must at least go across one link that is defined as an area 0 link.
>
>In a hub-and-spoke environment with a single hub router, it seems to me
>that
>there just is no good way to use multiarea OSPF if you don't extend area 0
>across the WAN links.
>
>At least, that's the way it appears at the moment.
>
>John
>
>| I'm having trouble wrapping my brain around a specific scenario and I
>| wanted to get your thoughts. Let's say we have a hub and spoke network
>| with a single router as the hub. There are five areas attached to the
>| backbone. It seems that we would have to extend area 0 across the WAN
>| links, but I'm wondering what would happen if we didn't.
>|
>| If we didn't, the backbone router would have no interfaces in area 0.
>| I'm wondering if this would cause some major problems. I bet that it
>| would but I'm having a hard time thinking through what actual problems
>| might arise. Would this backbone router just "know" that it was area 0
>| because it has interfaces in multiple non-zero areas and hence behave
>| correctly?
>|
>| One obvious problem is that the backbone router would be a member of
>| every area and would thus be pretty busy if the network got to be very
>| big. If we extended area 0 across the WAN link the backbone router
>| would be protected from running SPF calculations everytime a remote area
>| had a link change.
>|
>| What other problems would arise? Would this even work at all? I don't
>| really have the tools to try it or I'd just attempt this chaos myself.
>| As you can guess, we run eigrp everywhere so I'm still clueless to some
>| of the workings of OSPF in a production environment.
>|
>| Regards,
>| John
>|
>|
>|
>|
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