Subject: [babel] Summary of my comments about Denis' talk

From: Juliusz Chroboczek <[email-masked]>
Date: Fri, 18 Nov 2016 06:09:15 +0100

Concerning Denis' talk, I'm of the opinion that Appendix A should remain
an informative appendix.  Further constraining neighbour discovery and
link-quality sensing should only be done as a last recourse, and after
serious thought.

It is intended by the protocol that a neighbour only exists after it sent
a Hello.  If that's not clear in the spec, it should be clarified, or else
a different policy defined.  I'm not sure it matters much, though.

The spec is very clear about Acks: after your receive an Ack Request, you
MUST send an Ack within the deadling.  No other requirements are made --
how to deal with missed Acks is an implementation issue.

I believe that there is consensus that Hellos should not be further
constrained (thanks, David).  If the HMAC extension needs extra data, it
can put further constraints when HMAC is enabled -- for example, HMAC
could require the RTT extension (which is pretty cool, but requires
generating a timestamp for every Hello packet -- is that prohibitive?), or
it can put its own sub-TLV in Hello, or it can require that Hellos only be
sent in a packet that carries a TS TLV.  (The RTT extension does something
similar -- it requires that IHUs be only sent in packets that carry a Hello.)

-- Juliusz