Re: [Ospf-manet] Re: Regarding MPR-OSPF

Richard Ogier <rich.ogier@earthlink.net> Tue, 13 March 2007 21:31 UTC

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Date: Tue, 13 Mar 2007 13:31:06 -0800
From: Richard Ogier <rich.ogier@earthlink.net>
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To: Emmanuel Baccelli <Emmanuel.Baccelli@inria.fr>
Subject: Re: [Ospf-manet] Re: Regarding MPR-OSPF
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Emmanuel Baccelli wrote:

>
> To clarify a point which you indicate that you missed concerning the 
> synch router: the willingness parameter influences a routers 
> forwarding ability only. If a synch router is outside the MANET, then 
> according to the I-D there exists a hybrid router which will 
> synchronise with its whole neighbourhood, thus fulfilling the synch role.


OK. I knew that a hybrid router must select all neighbors as path MPRs,
but I missed the definition of the MPR set as the union of the path MPRs
and the flooding MPRs. So a router must become adjacent with all of its
flooding/path MPRs and flooding/path MPR selectors.
This could result in a lot of adjacencies when unequal metrics are used
(even more than you are obtaining in your GTNetS simulations).

But still, if there is no hybrid router, then the router with largest RID
is still treated unfairly since, as the synch router, it must become
adjacent with all of its neighbors.  In version 02, you used Willingness
to select synch routers, but I realize you can't do that easily now,
since you are now looking at all routers in the area.
(Note that MDR selection uses Router Priority, so OSPF-MDR does
not have this issue.)

I won't be at the Prague meeting, but plan to present an update
at the Chicago meeting in July.

If you are going to present simulation results at the Prague meeting,
can you provide your updated GTNetS code this week?
Or if you did not make any changes to the code other than making
the need_adjacency condition symmetric (as I suggested), then please
let me know (since I can easily make this change).

Richard

>
> We agree that the synch alternatives which you propose are complex and 
> potentially less performant, which is why we went with the above 
> solution which does the same thing without these inconveniences.
>
> Emmanuel
>
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