[Babel-users] battling with babel and route changes

[Juliusz Chroboczek]

[Copying to babel-users, by Dave's permission]

Dave, sorry if you already have, but could you double-check that you're
not NAT-ing or using a stateful firewall in your tests?

> but as for the issue of the route change problem perhaps it would be
> kind of cool to always have two routes installed of 1 different metric
> to eliminate the window, and changes like 'unreachable' messages move
> faster than babel can.

Babel does maintain alternate routes, and will switch immediately (as in
within microseconds) when a route is detected to be unreachable.  What
takes time is detecting when a neighbour goes down -- it takes up to
three hello intervals (losing a single hello should not trigger
a routing change).

> And to have a "I'm about to move" announcement...

We already have that -- just send an announce with a high (but finite)
metric, which causes other nodes to switch to their alternate routes.
A student of mine (Marko Mijatović) is currently working on a version of
babeld that uses this kind of tricks when power goes down.

> You can't possibly be done grading yet!

Heh.  No, I'm certainly not.

-- Juliusz