[Babel-users] Babel for use in a dense disconnected mesh network

[Jason Palmer]

> I am using the same hardware, and I have observed that the interface
> goes up and down spontaneously from time to time, probably because of
> USB rather than network issues.  It might help to check that you have
> one of the latest Raspberry Pi (better usb design) and that your power
> supply is sufficient. 
> [...]
> Gabriel

The Raspberry Pi does seem to have soem USB limitations which have been
affecting the stability of the wireless network. It took some work to
get the networking services to come up in a predictable manner,
especially with netcfg which is why I abandoned it in place of manual
systemd services. I have 40 of the Pi's, 10 of the first version and 30
more recent. I had issues early on which highlighted the importance of
the power supply when using the Raspberry Pi as an experimental
platform. For these recent tests some were still sharing power supplies
which isn't ideal, but is adequate. The USB wlan adapter was the only
attached peripherial for these tests.  


> I'm no wifi specialist, but I found this to be a very interresting
talk:
>
https://www.usenix.org/conference/lisa12/building-wireless-network-high-
density-users
> There might be some useful tips in there ?

Thank you for the link, it does have some useful information. I have
been keeping an eye out for technical papers relating to
event/conference Wi-Fi network design for tips on this project. 

>> [Service]
>> ExecStart=/usr/bin/babeld -D
> I'm certainly no systemd specialist, but should this either say
Type=forking, or not use the -D flag?

Yes, I should have been using the Type=forking and passing the PID file
to systemd. I was originally calling babel without the -D flag, but
changed the ExecStart line in this service file (and altered the
mesh.service file) due to sequencing issues with initialising the USB
adapter and corresponding wlan0 interface before babel was started. I
had issues with babel if it was called before the wlan0 interface
existed, though this may have again been a configuration error on my
part. 

Regards,
   Jason