Re: [B.A.T.M.A.N.] Suggestion for routing improvement on poor links

Andrew Lunn
2014-02-20T10:10:45Z

> Hi Andrew,
>
> >
> > That is not what i have seen in practice. Because the metric is good,
> > and does not degrade,
>
> The missing degradation is the part where I don't agree.
>
> Just to be sure we are understanding each other, I am talking about the
> scenario depicted in this picture:
>
> http://www.open-mesh.org/attachments/download/52/triangle.png

Thanks for the diagram. Yes, Linus and I had a somewhat similar setup.
We had more nodes involved, and B was walking around the inside of a
building.

> 'A' is the source node and 'B' is our destination. B moves and breaks
> the line-of-sight with A, thus making the A<->B link unusable at all (we
> assume that now packet loss on A<->B is 100%).
>
> At this point A still receives B's OGMs via N1.
>
> According to batadv_iv_ogm_orig_update() (in bat_iv_ogm.c) each time a
> packet with a _new_seqno_ is received the global window of _each_
> neighbour for the given originator is shifted by one slot and the
> averages are computed again.

It is a couple of years since Linus investigated this. So maybe things
have changed. If it does work like this, great, that helps solves a
problem we had. I don't currently have access to a system to test this
though.

Andrew