[Babel-users] Bebel for hamradio frequency

[Juliusz Chroboczek]

> We can use olsrd on our frequency and channels below 1 but when I try
> use BABEL on our frequency I have in log message

> Couldn't determine channel of interface mesh0 ....

As Denis noted, babeld expects channel numbers to be between 1 and 254.
It is assuming that the kernel is reporting incorrect channel numbers, and
makes worst-case assumptions about radio interference.  This will cause
sub-optimal routing if you have multiple radio frequencies in your mesh,
but no worse than what happens with OLSR (which doesn't take radio
interference into account).

You can work around this issue by setting babeld's idea of the channel
number manually by putting something like this in /etc/babeld.conf:

  interface mesh0 channel 42

The actual numbers make no difference, but please choose the channel
numbers so that babeld has an accurate idea of the radio interference
patterns in your mesh.  Precisely:

  - the channel number should be the same on both sides of a link;

  - if two interfaces interfere (they cannot be used at the same time),
    they should have the same channel number;

  - if two interfaces don't interfere (they can be used at the same time),
    they should have different channel numbers.

Other possible tweaks include "noninterfering" interfaces (wired,
directional antennas, etc.), and "faraway" interfaces (which split routes
into independent interference domains).  Please check the manual page for
details.

Babeld's radio interference algorithm is described in

    https://tools.ietf.org/html/draft-chroboczek-babel-diversity-routing

-- Juliusz