From: Ouellette, Tim (tim.ouellette@eds.com)
Date: Thu Feb 20 2003 - 07:26:41 GMT-3
How do you define the "backbone"
Let me ask it this way. If I have 50 routers in area 1 (only 1 area) is
area 1 really the "backbone". I say No. When I think backbone, I think
multiple ospf areas with 1 transit inter-area backbone.
Per the RFC as quoted below
" The OSPF backbone always contains all area border routers. The backbone
is responsible for distributing routing
information between non-backbone areas."
In order for a router to be an ABR under "sh ip ospf" it must be connected
to 2 different areas and one of those areas HAS to be area 0. If you
connect at router to area 1 and area 2, it won't be an ABR until you either
connect it directly to area 0 or do a virtual-link or tunnel... Thus
satisfying the requirement of being "connected" to area 0.
In short, If you want to run OSPF in one area, it can be ANY number you
want. If you want to run multi-area OSPF, one of the areas HAS to be area
0.
Tim
-----Original Message-----
From: Georg Pauwen [mailto:pauwen@hotmail.com]
Sent: Monday, February 17, 2003 5:12 PM
To: mdye@bevillcntr.org; groupstudy@comcast.net; markmiller@alltel.net;
sam@munzani.com; ccielab@groupstudy.com
Cc: cciesecurity@yahoogroups.com
Subject: RE: Can you have OSPF without area 0 at all?
Mark,
just try to build an OSPF network with e.g. area 1 as the backbone, you will
see it works just fine. Not much need to disagree about this, fact is it
works.
Regards,
Georg
>From: mdye@bevillcntr.org
>Reply-To: mdye@bevillcntr.org
>To: Joe <groupstudy@comcast.net>, "'Mark Miller'" <markmiller@alltel.net>,
> "'Sam Munzani'" <sam@munzani.com>, ccielab@groupstudy.com
>CC: cciesecurity@yahoogroups.com
>Subject: RE: Can you have OSPF without area 0 at all?
>Date: Mon, 17 Feb 2003 14:23:13 -0600
>
>I agree with Joe. OSPF has full knowledge of Area 0 being the backbone. All
>OSPF implementations must have an area 0.
>
>The current RFC for OSPF (2328) says:
> " 3.1. The backbone of the Autonomous System
>
> The OSPF backbone is the special OSPF Area 0 (often written as
> Area 0.0.0.0, since OSPF Area ID's are typically formatted as IP
> addresses).
The backbone must be
> contiguous. However, it need not be physically contiguous;
> backbone connectivity can be established/maintained through the
> configuration of virtual links.
>"
>
>Mark Dye
>
>
>At 02:34 PM 2/17/03 -0500, Joe wrote:
> >Please send us the link you refer to. I have to say that this is simply
> >not true. You will ONLY send routes from your area, whatever it may be,
> >into area 0, the backbone, so you can't just arbitrarily designate any
> >area as the backbone. It MUST be area 0.
> >
> >Joe
> >
> >-----Original Message-----
> >From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> >Mark Miller
> >Sent: Friday, February 14, 2003 6:15 PM
> >To: Sam Munzani; ccielab@groupstudy.com
> >Cc: cciesecurity@yahoogroups.com
> >Subject: Re: Can you have OSPF without area 0 at all?
> >
> >
> >The routing process in ospf has no concept that "area 0" is the backbone
> >area. You can make it any number you want. I remember reading
> >something on this. I'll try to dig it up and send you a link.
> >
> >Mark Miller
> >
> >
> >----- Original Message -----
> >From: "Sam Munzani" <sam@munzani.com>
> >To: <ccielab@groupstudy.com>
> >Cc: <cciesecurity@yahoogroups.com>
> >Sent: Friday, February 14, 2003 12:56 PM
> >Subject: Can you have OSPF without area 0 at all?
> >
> >
> >> Team,
> >>
> >> I came across an interesting finding. I want to take everybody's
> >> opinion
> >on this before putting anything in production. We are building an OSPF
> >network that will eventually merge with company's main OSPF backbone
> >network. The core group has assigned us ospf area number 555.
> >>
> >> When I configure all my routers with OSPF area 555(with no area 0 at
> >> all),
> >it seems to be building up routing table. I always thought OSPF needs
> >area 0 to function. Will this work of we add a non cisco device with
> >area 555 configuration?
> >>
> >> What is the catch 22 in this configuration? I have started reading
> >> OSPF
> >RFC to figure out all technical details.
> >>
> >> Thanks,
> >> Sam Munzani
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