Re: Mailing list and draft charter for new multihoming BOF/WG

[Jari Arkko <jari.arkko@piuha.net>]

Brian E Carpenter wrote:

> Now about separating state management. Firstly I wrote the
> text to retrospectively justify Kurtis's suggestion to have
> a separate document, and I don't know if I correctly read his
> mind.
>
> Secondly, when I began to think about it, I really did see an
> argument for *consciously* designing the state machine separately
> (and logically, it should be designed first, not second).
>
> Who's to say that we'll get the protocol right first time? It acts
> in support of the state machine, not the other way round, so the
> state machine is actually fundamental. Going to a v2 of the protocol
> probably shouldn't change the state machine, at the macro level.
>
> Also, the state machine will not only respond to shim6 protocol events.
> It will also have to respond to unreachability signals, transport
> disconnect signals, etc.

This is all true, but past experience suggests
that state machines tend to be necessary for
the definition of the semantics of protocol
events, and that protocol messages tend to be
necessary for the development of state machines.
This speaks for the treatment of the two as a
whole. Different sides of the same coin. Whether
those are in the same or different document is
another matter perhaps.

(By the way, I think that we in the IETF have not
used state machines quite as much as we perhaps
could have. They do look boring, but they also
help people ensure that all special conditions
have been well defined.)

--Jari