Re: draft-bourbaki-6man-classless-ipv6-00

[Erik Kline <[e-mail]>]

On 6 June 2017 at 07:25, Brian E Carpenter <[e-mail]>
wrote:

> On 05/06/2017 19:45, Lorenzo Colitti wrote:
> > On Mon, Jun 5, 2017 at 8:05 AM, Brian E Carpenter <
> > [e-mail]> wrote:
> >
> >> None of that is the point. The point is to establish
> >> that routing is classless
> >
> >
> > Routing is already classless because BCP 198.
> >
> >
> >> and /64 is a parameter of specific addressing schemes.
> >>
> >
> > It *is* a parameter. The parameter's value is 64 for all unicast
> addresses
> > except those starting with 000.
>
> The parameter's *current* value, yes. But should we really be fixing
> the value of the parameter once and for all in the addressing architecture?
> Why don't we fix it in each IPv6-over-foo, which is what the SLAAC design
> assumes?
>

Because I doubt there is any good argument about things specific to the Foo
layer for having something shorter than a 64 when 64 gets you many so nice
guarantees for randomness, security and non-collision.

This document does not include a problem statement -- it doesn't say what
problem exists that need solving.

If all this is about being able to execute the OS-specific equivalent of
"ifconfig eth0 add 2001:db8::1/123" then I think that should absolutely
work fine.  We should file bugs to get OS tools to understand what this
actually means.

That, however, is completely orthogonal to 64bit IIDs.  The 64bit boundary
pretty much only has meaning in a SLAAC context.  Not doing SLAAC?  64bit
IIDs don't really affect to you then.  If OS's make assumptions that there
must be some 2001:db8::/64 route when in fact 2001:db8::1/123 was specified
then that's an obvious error.  IMHO, if /n isn't specified: use n=64 and if
/n is specified then use /n.  Seems simple enough.  You can put a /123 PIO
in an RA so why not on a command line.

This document however burns down the whole house for the sake of lighting a
candle that was in fact already lit.

The only thing meaningfully affected by removing 64bit IIDs is removal of
the last backstop that ensures network operators and users alike share --
however unequally -- the benefits of IPv6 and it permanently demotes IPv6
to little more than 128bit IPv4 with quaint, warty rules about fragments
and extension headers.