[Babel-users] Unscheduled Unicast Hellos: some background on 802.11 link quality estimation

[Juliusz Chroboczek]

> I'm wondering... what if, in the hypothetical routing protocol "Babble",
> one got rid of multicast hellos and ETX entirely, and routed using RTT
> measured by unicast hellos.

Interesting idea.

I think that's a perfectly legitimate implementation of Babel with Unicast
Hellos: we're leaving the cost computation algorithm unspecified, ETX is
just an implementation suggestion in Appendix A.

> Wouldn't this take delays from ARQ'ed packet oss into account have
> results somehow similar to ETX?

802.11 has a default ARQ timeout of 1µs, which is likely to be drowned by
congestion.  I guess the only way to find out is to try it out.  You'll
need to change the packet format of the ETX extension, which only has 1µs
granularity.

-- Juliusz