From: Brian Dennis (brian@labforge.com)
Date: Sat Jul 05 2003 - 13:52:15 GMT-3
In the real world you would change the OSPF network type for a BRI or a
PRI when you are connecting to more than one remote site at a time. A
point-to-point network type which is the default for OSPF on a BRI and
PRI can only form an OSPF adjacency with one remote site at any given
time. The solution is to change the OSPF network type to
point-to-multipoint which will allow an OSPF adjacency to be formed with
multiple route sites.
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
ccie2be
Sent: Saturday, July 05, 2003 5:42 AM
To: Group Study; Brian McGahan
Subject: Re: OSPF Demand Circuit
Hi Brian,
Thanks for your reply.
In another ospf related post, I was wondering about the reason or
benefit
for changing the network type from it's default to point to point.
Nobody
(as yet ) posted a response. Do you know under what circumstances this
is
something that should (or is required) be done? Thanks very much. Jim
----- Original Message -----
From: "Brian McGahan" <brian@cyscoexpert.com>
To: "'ccie2be'" <ccie2be@nyc.rr.com>; "'Group Study'"
<ccielab@groupstudy.com>
Sent: Friday, July 04, 2003 1:41 PM
Subject: RE: OSPF Demand Circuit
> Jim,
>
> This TAC document is wrong. The purpose of running OSPF demand
> circuit is to maintain an accurate view of the routing topology, while
> minimizing the amount of time that your DDR link is up solely due to
> routing protocol traffic.
>
> By denying OSPF as interesting traffic, adjacency cannot be
> maintained over the DDR link unless it is up for some other reason.
> When the link goes down due to no interesting traffic passing over the
> link within the idle timeout, OSPF adjacency will be lost as soon as
the
> dead interval expires.
>
> When running OSPF demand circuit, OSPF *should* be specified as
> interesting traffic.
>
> HTH,
>
> Brian McGahan, CCIE #8593
> Director of Design and Implementation
> brian@cyscoexpert.com
>
> CyscoExpert Corporation
> Internetwork Consulting & Training
> Toll Free: 866.CyscoXP
> Fax: 847.674.2625
>
>
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > ccie2be
> > Sent: Friday, July 04, 2003 5:22 AM
> > To: Group Study
> > Subject: OSPF Demand Circuit
> >
> > Hi,
> >
> > After checking the archieves, I didn't find anything that
specifically
> > addressed this question, so here goes.
> >
> > I thought that when a BRI interface is configured as an ip ospf
> > demand-circuit, it will automatically suppress ospf hello's as long
as
> the
> > interface is configured as a p2p or p2m ospf network type.
> >
> > However, in the example at
> > http://www.cisco.com/warp/public/129/config-bri-map.html , it shows
an
> > access
> > list being used to prevent ospf hello's in addition to the ip ospf
> > demand-circuit command being configured.
> >
> > Is it really necessary (or just sometimes necessary) to use an
access
> list
> > to
> > deny ospf hello's (packets addressed to 224.0.0.5) when one side of
> the
> > isdn
> > circuit is configured as an ip ospf demand circuit? If so, why is
> that?
> > Also, if the access-list in addtion to the ip ospf demand circuit is
> only
> > needed in certain situations, what are those situations?
> >
> > Thanks, Jim
> >
> >
> >
>
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