Re: encoding link ID in link-local addrs (Re: about violation of standards)

[神明達哉 <[e-mail]>]

At Fri, 19 Apr 2019 10:44:50 -0700,
Erik Kline <[e-mail]> wrote:

> > - whether the goal is really impossible to achieve with currently
> >   available tools
> > - especially if the first answer is something like "it can, but it's
> >   not convenient", then whether the goal really justifies to consume
> >   a particular space of the finite resource of address space
> > - whether it has to be inside the upper 64 bits (or in more general,
> >   inside the "subnet prefix" part).  If it has to be so, whether it
> >   has to be within the first 32 bits (if not, at least it doesn't
> >   conflict with the BSD implementation).
>
> The thing here is that the standard currently keeps the 54 bits between
/10
> and /64 as zero-valued.  As such, an implementation can lean on the
> standard for safety to create a non-standard internal representation
where,
> say, in6_addr.s6_addr32[1] = ifindex.
>
> *Not* changing the standard actually gives cover to what people want to do
> internally.  Changing the standard opens this space up for other competing
> uses that might need to be given consideration and, IMO, only serves to
> confuse matters.
>
> No change to any standard is required here, as I currently see it.

Sure, that's my current position, too.  So the bar for justification
is very high, but I personally wouldn't just deny any discussion for
the possibility outright, hence "open to discussion".  Some others,
perhaps including you, might think the bar is too high to even
consider the possibility.  I wouldn't be that strict, but it's also
understandable.

--
JINMEI, Tatuya