From: dude (navinie@gmail.com)
Date: Mon Jun 04 2007 - 09:41:26 ART
Hi,
I think the correct method is to use the Priority 0 on spokes. U should use
the broadcast statement as I assume, the question has not said otherwise.
Also, in a point to point setup, the OSPF Hellos originated from the spokes
will carry the DR and BDR field as 0.0.0.0 whereas the Hub will cary the DR
field with the router id of itself. The adjacency would form. Now, the issue
is the LSA types that they would orriginate. The spokes will send a LSA as
type 1 where as the hub will send a LSA as type 2. This header mismatch
might result in errors in the LSA database or SPF algorithm. Maybe I need to
try simulate this and find out what exactly happens.
Regards,
Navin
On 6/4/07, Ronnie Angello <ronnie.angello@gmail.com> wrote:
>
> Non-broadcast and point-to-point are not compatible network types.
> Adjacencies may form when you change the timers but routes will not be
> exchanged properly. Only non-broadcast and broadcast support DR election.
> Since it says you can't use neighbor statements, broadcast is your only
> option.
>
> On 6/3/07, Jason Guy (jguy) <jguy@cisco.com> wrote:
> >
> > Hi everyone. I have been digging into OSPF a little today while working
> > on a practice lab.
> >
> > The requirement asks to set up OSPF over the frame relay hub and spoke.
> > Frame relay is running on the main serial interfaces. It says not to
> > use neighbor statements under OSPF, and ensure the hub is always the DR.
> >
> > The default is ospf interface type is NON-BROADCAST, which does not
> > allow the hellos to multicast. So I thought I can set the spokes to
> > POINT-TO-POINT, and leave the HUB NON-BROADCAST but set the hello and
> > dead timers to 10 and 30 respectively.
> >
> > This did bring the neighbors up and it does ensure the hub is the DR
> > since the spokes cannot be DR. However the solution sets all routers to
> > BROADCAST, and sets the ip ospf priority to 0 on the spokes OSPF
> > interface to ensure the hub is DR. I am sure this is a valid solution
> > as well.
> >
> > So, I did some searching on the achieve and surprisingly could not find
> > much on this. So my question is this:
> >
> > Which method would be correct?
> >
> > In the real lab, is it fair to change the ospf timers, especially when a
> > later requirement requires OSPF fast hellos set up?
> >
> > The reason I ask is I understand the exam is graded with a script. Is
> > there multiple "correct" answers coded in it? Or did I miss a subtle
> > clue that should have pointed me to using BROADCAST all around rather
> > than a mix of network types?
> >
> > Thanks in advance,
> > Jason
> >
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>
>
> --
> Ronald Angello
> CCIE #17846
>
> _______________________________________________________________________
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