Re: [B.A.T.M.A.N.] two-radio nodes and alternative next hop

Axel Neumann
2008-04-24T08:09:05Z

Hi,

On Donnerstag 24 April 2008, Jan Hetges wrote:
> and something completely different: i think, .4.1 should choose the
> direkt link to .4.162 instead of going through .4.160 (and vice versa)
I experienced the same. Sometimes, from the end2end throughput point of view,
it would be better to choose the direct route and sometimes not. I played a
lot with the metric in charge of the final route. But in the end I am unsure
which parameters are responsible for that or whether the better path can be
identified over several hops at all (perhaps if we take hop-by-hop bandwidth,
interference, load, and other stuff into account). You could twist the metric
so that it always prefers end2end routes with less hops but I think in the
end it is most important to have a general and unique metric applied to every
routing instance in your mesh.

Don't know if you want to hear it? You can play with --dups-ttl-degradation X
(current default is X=2). This degrades the preference for a path by 2
percent with every additional hop (relative to the shortes path). So if you
use 50 instead, a node with two alternative paths (one single-hop and one
two-hop path) to a given destination will ignore 50% of the OGMs received via
a two hop path. Then it will probably choose the single-hop path.
And of course, if you find a value which works general better for all your
nodes then let us know.

ciao,
axel

>
> cheers
>
> --Jan