Today's mesh testing.

[Jim Gettys]

Wonderful stuff!
                  - Jim

On Sun, 2008-03-02 at 19:05 -0500, 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.
-- 
Jim Gettys
One Laptop Per Child