[Babel-users] more wet paint - babel unicast IHU for short-rtt path optimization

[Juliusz Chroboczek]

> My understanding of the babeld code is that unicast code is in there
> but not used, and if it were used, it would not work against existing
> babel daemons. ?

You MAY send any Babel TLV over unicast except a Hello.  Hellos MUST be
sent over multicast.  The receiver doesn't care (except for Hellos).

Look at message.c, function send_ihu.  around line 1693.  If there's
already a unicast TLV queued, then the IHU is appended to that, and sent
over unicast.  Otherwise, the IHU is appended to the multicast buffer.

There would be no problem sending all IHUs over unicast, but it would
probably cause additional NDs.  A more productive endeavour would be to
send updates over unicast when there are few neighbours on a given
interface, but I'm afraid it might cause Babel more difficult to debug.

-- Juliusz