Wireless Battle Mesh 2009 (Paris) - aftermath

The /tmp/lab crew called wireless mesh protocols to a gathering in Paris. As
it seemed to be a good place to exchange ideas and testing our latest stuff we
decided to join this event.

We were positively surprised to find out that the area around the
/tmp/lab is very suited for wireless testing: lots of free space, packet loss
and collisions.
Nico from the OpenWRT team prepared all images + packages for the various
setups and helped all teams to solve OpenWRT related issues. Great job!
The B.A.T.M.A.N. project was supported by a French team consisting of
massoud, xeu and loloster. They helped us flashing the routers, placing them
outside and configuring batman. Before this event they were not using batman at
all, hence it was very interesting for us watching them interacting with the
batman daemon. They managed the setup very well and we had a lot of fun.
Thanks!

As we wanted to use the occasion to test batman layer 3 we decided to run the
trunk (revision 1244 at this time). On top of that we were running the batman
vis server to visualize the topology using s3d. The debian s3d packages
worked like a charm - thanks Sven!

The good:

• Batman (including all its flavors) has an excellent OpenWRT integration.
  The batman team was the first one ready to deploy despite the lack of
  mesh / batman experience (other teams needed considerably longer).
  
• The daemon is easy to setup & manage. We did not give introduction
  talks or training of any sort to our French friends. We let them start
  and whenever needed we explained a feature to them (e.g. how to activate
  internet gatewaying).
  
• The routing was stable and at its optimum.
  
• The traffic overhead created by batman is reasonable (much lower than
  other protocols but not the lowest). There is room for more improvements.
  
• Batman handles full & half internet tunnels without problems. No other
  protocol has a working solution for multiple natted gateways although we
  heard whispers that the idea of tunneling towards the gateway is spreading.
  We are looking forward to compare the implementations.
  
• The 3D visualization of the topology still is an eye opener. ;-)
  

Lessons learned:

• We can reduce the traffic overhead even more. Batman could throw away
  quite some packets without hurting the routing decision.
  
• The packet aggregation works but the TQ values are going down if the
  aggregation is enabled. It might be related to a higher probability of
  collisions when the packet is bigger or we have a bug somewhere.
  
• Compared to other protocols batman is slow converging over many hops.
  

The event was a great success. We had many discussions with other
mesh people which will help all involved parties to move forward. For future events
it would be nice to have a database of difficult scenarios for comparing protocols
with each other. Also, more testing on layer 2 would be interesting which requires
hardware that supports linux 2.6.

We are looking forward to the next Wireless Battle Mesh,
the B.A.T.M.A.N. team