From: Jezz Bird (jezzbird@hotmail.com)
Date: Fri Oct 19 2007 - 05:44:26 ART
Hi James,
I am not sure I've got the topology entirely right in my head, but it might be
that when you have the one link between the ABRs in area 0 ABR2 would choose
the 80 paths as they are INTRA-area routes and going via ABR1 would be
INTER-area routes. However once you have the link in area 1 you then have
intra-area routes via ABR1 aswell.
Regards,
Jezz.> Date: Thu, 18 Oct 2007 19:27:24 -0700> From: j4m3sm63@yahoo.ca>
Subject: Re: OSPF - area design question> To: smorris@ipexpert.com;
ccielab@groupstudy.com> > I think what I was looking for was an idea of what
constitutes a discontigous> area. In my example I had a regular router in
area1 only ... connected with 2> PTP links back to 2 separate ABRs ... each
link a different cost. The ABRs> were connected together with only a single
link in area0 ... in my lab routing> was not working properly. I.e. ABR1 saw
paths to the area router via it's link> at cost 40 and ABR2 only saw it's own
path to the area router at the cost of> 80 (those were my set costs) ... it
should see the path via ABR1 as better but> it wasn't. > > When i enabled a
new link between the ABR's in area1 then it> worked properly. > > Hope this
makes sense the way i describe ... i'm a bit> burnt out at the moment :)> >
Thanks> > ------------------------------> Jim> MacDonald> j4m3sm63@yahoo.ca>
------------------------------> > ----- Original> Message ----> From: Scott
Morris <smorris@ipexpert.com>> To: James MacDonald> <j4m3sm63@yahoo.ca>;
ccielab@groupstudy.com> Sent: Thursday, October 18, 2007> 9:58:21 PM> Subject:
RE: OSPF - area design question> > Per your other e-mail, I> don't think it
has anything to do with a> "worthy"> question or not, just that> ASCII art is
scary. :)> > In any event, I'm not sure what your basic question> here
actually is.> If> you are looking as to whether this is a valid network>
design or not,> the> short answer is no. Per OSPF RFC, everyone inside an
area> must have an> identical database for that area. Having ANY discontiguous
area> screws> that> up.> > We can fix that with tunnels or virtual links, but
that> doesn't make it> a> good idea!> > The whole point of an area is an
addressing> hierarchy, which> theorhetically> gives us the ability to
aggregate/summarize> our routes for more> efficient> routing. If you start
band-aiding things> together, you'll slowly> degrade> that idea to where it
just plain doesn't> work.> > HTH,> > > Scott Morris, CCIE4
(R&S/ISP-Dial/Security/Service Provider)> #4713,> JNCIE-M> #153, JNCIS-ER,
CISSP, et al.> CCSI/JNCI-M/JNCI-ER> VP -> Technical Training - IPexpert, Inc.>
IPexpert Sr. Technical Instructor> > A> Cisco Learning Partner - We Accept
Learning Credits!> > smorris@ipexpert.com> Telephone: +1.810.326.1444 > Fax:
+1.810.454.0130> http://www.ipexpert.com> -----Original Message-----> From:
nobody@groupstudy.com> [mailto:nobody@groupstudy.com] On Behalf Of> James
MacDonald> Sent: Monday,> October 15, 2007 10:05 PM> To:
ccielab@groupstudy.com> Subject: OSPF - area> design question> > In an
environment with 2 core routers in ospf area 0> connected> back-to-back> ...
and a distribution router in a separate area> connected to both> cores> with
PTP links ... do i need another link between the> cores within the> same>
regional area for continuity of the area??? The ASCII> art version of> the>
network would be like this:> > _area1_ RTR1 _area1_> /> \> / \> C1 ----- area
0 ------ C2> so do I need this?> > > _area1_ RTR1 _area1_> > /> \> > /> \> >
C1 \ ----- area 0 ----- /> C2> \----- area 1 ------/> > > Hope this> makes
sense ... my formatting may mess up in email ... > > Thanks,>
------------------------------> Jim MacDonald> j4m3sm63@yahoo.ca>
------------------------------> > > > > Get a sneak peak at> messages with a>
handy reading pane with All new Yahoo! Mail:>
http://mrd.mail.yahoo.com/try_beta?.intl=ca>
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