[Babel-users] Debriefing: Babel workshop at Pas Sage en Seine 2013

[Baptiste Jonglez]

Hi,

I just realized I forgot to write about the Babel workshop at Pas Sage
en Seine, which was more than two weeks ago.

I first gave a short presentation, mostly to recall basic network
concepts, see [1] or [2] (in French).  The slides are available
at [3].

Then, there was about one hour of workshop: people could come with
their laptop, install babeld and ahcpd and connect to the mesh network
deployed there.

There were about 15 people with laptops, and someone had a router (but
I don't think he managed to connect it to the mesh, unfortunately).
Most people got it working, but some didn't.  We've had one kernel
panic, and a few people that were on the wrong ad-hoc cell, even
though they were using the same channel; we might have hit the cell
limit, or simply a bug in their wireless driver.

The base network was built using a raspberry pi (exporting a route to
the Internet) and four TP-Link WR703N, of which two were talking with
the raspberry pi over the existing wired network.  Everybody was using
the same wireless channel.

Shortly after the workshop, the network looked like this:

  http://ze.polyno.me/babel/babelweb-pses2013-1.png

Another capture showing feasible routes:

  http://ze.polyno.me/babel/babelweb-pses2013-2.png

There are about ten screenshots of babelweb available at [4].


The goal was to get people to discover and play with Babel, and show
that it works in practice; I consider this workshop a success on this
regard, even though it was somewhat disorganized.  The workshop was
held on Saturday, but a few people connected to the mesh network again
on Sunday :)

On Fri, Jun 21, 2013 at 02:46:57PM +0200, Juliusz Chroboczek wrote:
> I've just received this from our common friends:
> 
>   http://www.pps.univ-paris-diderot.fr/~jch/cantine-20130621.jpeg

Nice shot!

We actually haven't used the Foneras, since we experimented with the
TP-Link WR703N [5] on OpenWRT AA.

These routers are small but excellent.  Compared to the Fonera, they
draw almost no power: a Fonera gets very hot within tens of minutes,
while the TP-Link were still cold after 3 days of intensive use.

Since they have an USB port, it would be easy to turn them into cheap
multi-radios routers using an USB dongle.

However, they have a few drawbacks:

- limited flash space.  A friend successfully bundled babeld, ahcpd
  and tor, but it was tight.

- no external connector for antenna.  Note that there are hardware
  hacks to do this anyway [6].


Regards,
Baptiste

[1] http://lacantine.ubicast.eu/videos/22-06-2013-124257/
[2] http://transmission.progval.net/PSES2013/reseau_mesh.mp4
[3] http://ze.polyno.me/babel/slides-mesh-pses-20130622.pdf
[4] http://ze.polyno.me/babel/babelweb-pses2013-nomac.tar
[5] http://wiki.openwrt.org/toh/tp-link/tl-wr703n
[6] http://wiki.openwrt.org/toh/tp-link/tl-wr703n#hardware.mods
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