[Olsr-dev] Modification to the MPR selection algorithm

Henning Rogge (spam-protected)
Wed Jun 9 22:03:29 CEST 2010

Am Mittwoch 09 Juni 2010, 21:52:57 schrieb Ayan Roy-Chowdhury:
> At present, we want to change the MPR selection algorithm only. The
> route selection will still be based on shortest path in terms of hop
> count. However, the local view of the network will consist of nodes with
> more stable links, and therefore, the shortest paths will be more stable.
> > If you want to affect the route of the traffic, just forget about MPRs
> > and work on a better routing metric plugin. I would be happy to see
> > postprocessing for ETX that gives instable links a "penalty" and
> > stabilize the metric value with this.
> Once we have the new MPR algorithm implemented, the next step will be
> to change the route selection algorithm to find the optimal routes based
> on most stable links (or some other metric). So we will run Dijkstra on
> the weighted graph. But this will be possible only after the MPR
> selection algorithm is changed.
The main problem with MPRs for linkcost based routing is that there is no 
datastructure to store multiple linkcosts from neighbor to two-hop-neighbor.

The 2-hop database is node-based, not interface based (a design problem for 

> Would it be possible to get the fix assuming it does the job, despite
> bugs? To compare the overhead between the default OLSR implementation,
> and the SPTC algorithm, it is necessary that TC redundancy is set to 0.
I will see what I can do... my first fix was just to 'complex' and it got 
worse, I will erase some code and try to start again.
> > I would advice to directly work on a routing metric plugin that outputs a
> > more stable metric value. That would be a GREAT contribution for future
> > OLSRd versions.
> We are hoping that we will get to that point soon!
I'm looking forward to this.

Henning Rogge

1) You can't win.
2) You can't break even.
3) You can't leave the game.
— The Laws of Thermodynamics, summarized
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