Hello James, Nicholas & others,

Please allow me to join the conversation:

Le dimanche 14 février 2021 à 11:23 -0500, James Carlson a écrit :
> RFC 2472 is a little weird with respect to the Interface-Identifier
> option.  It's possible to send an all-zero identifier, but we're really
> in uncharted waters if the peer can't give us an address or rejects the
> option.

Could I suggest that then IPv6CP just fails?

> This sort of makes sense given that IPv6 itself just doesn't
> work at all (no ICMPv6 ND means no work gets done) without a local
> address, so it's not something anyone has really explored.

Well, I actually sent last year a patch (attached again to this
message) to Paul and Cc'ed here about sending a zero identifier to do
exactly (to my understanding) what Nicholas is intending to do: let the
“server”-side choose the interface identifier.

It is a very small change that is basically activated on the “client”-
side with:

  ipv6 ::,

thus sending a zero identifier for our side. It worked quite well for
my work case (virtual serial links), where having short addresses when
autoconfiguring helps a lot, too. I couldn't resist also citing the
“stability to global scope addresses” argument from the RFC, which is
indeed relevant to me, at least.

What do you think about it?
Regards,
--
Benjamin