Today's mesh testing.

John Watlington wad at laptop.org
Sun Mar 2 22:13:25 EST 2008


Thanks for the info !   This is good news, as it means that schools
up to a hundred students should work right now, given a school server
and three active antennas...

wad

On Mar 2, 2008, at 7:05 PM, Chris Ball wrote:

> Hi,
>
> Daf and I got the school server jabberd/shared roster working today.
> We connected/registered 32 laptops to it with mesh TTL set to 1 for
> broadcast, and they were all able to see and join a shared chat  
> session
> with each other.  The workload on the spectrum analyzer increased from
> 18% (no-one connected) to 26% (all connected).  The chat session is
> consistent -- no-one is dropping out and new messages are seen by each
> laptop, with a few seconds of lag.
>
> With the mass chat session still running, we shared a 500KiB PDF.   
> First
> we joined the shared Read session with one laptop, and the download  
> took
> 16 seconds to complete.  We then joined two more laptops at once, the
> first download took 26 seconds and the second finished at 30 seconds.
> Five more at once: all finished around 1m00s.  Ten more at once:  the
> first finished at 2m18s, the last finished at 2m40s.  There were no
> failures downloading the PDF.  The sharing was unicast TCP, with mesh
> TTL set to 1, which explains the slightly worse than linear  
> increase in
> download time for more laptops downloading at once.
>
> This is much more anecdotal than the full test plan, but we thought  
> the
> testers currently in Peru would want to know what they can expect from
> the school server setup ASAP.  We don't have more laptops upgraded and
> ready to join the network yet, but we don't have any reason to believe
> we've saturated the network -- with the PDFs downloaded and Chat still
> running, the duty cycle on the spectrum analyzer is now at 28%.  (In
> general, wireless networks seem to start degrading around 40%.)
>
> - Chris and Daf.
> -- 
> Chris Ball   <cjb at laptop.org>
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