Monday's Testing

david at lang.hm david at lang.hm
Thu Mar 27 20:14:15 EDT 2008


On Thu, 27 Mar 2008, Martin Langhoff wrote:

> 2008/3/27 Ricardo Carrano <carrano at laptop.org>:
>> My suggestion for the Cambrige testbed is:
>> 1 - Validade probe response driver patch submitted by Marvell and implement
>> it
>> 2 - Increase contention window from 7,31 ro 31, 1023
>>  3 - Increase route expiration time from 10 to 20 seconds
>> 4 - Increase mcast rate from 2 to 11 Mbps.
>>
>> All of the above are trade offs and should be considered in dense mesh
>> scenarios only. Based on what I see in my own testbed, they will reduce the
>> duration of bursts and also make you more resilient to them.
>
> Hi Ricardo,
>
> if this improves the behaviour in dense mesh scenarios, am I right in
> thinking we'll be looking at - from a high-level pov - changing
> contention window, route expiration and mcast rate dynamically on the
> XOs when they see the school server antenna with a strong signal, and
> then again when they lose sight of it. I am not familiar with the mesh
> driver so this may be a stupid question - is it safe to change those
> values on the fly?
>
> The switch-modes decision logic could be tricky
>
> -  needs data from different network layers
> -  needs tuning to avoid having ranges where we switch back-and-forth
>
> still getting to grips with how the mesh works - hopefully the above
> makes sense ;-)

it may be that it's not a case of 'mode A' vs 'mode B' but is instead a 
continuous function based on how many other nodes that it sees. with small 
changes based on the number of nodes it won't matter much if it bounces 
around as the number of nodes change (as long as it doesn't waste a lot of 
power to make the change)

David Lang


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