Re: IPv6 prefix lengths - how long?

[Yucel Guven <[e-mail]>]

About Point 2:
No, I think should not be disallowed. We should not restrict addresses to
be on the nibble boundaries.
(Might that 'mimic' the the classfull addresses of v4? Maybe)
One useful/practical reason of having prefixes on nibble boundaries is
that it makes easy entering/registering the DNS records,
e.g.  if you have /64 (or multiples of 4 -since a nibble has 4bits, in
general), then only one DNS record is needed,
if it's a non-nibble prefix, then more than one DNS entry should be
recorded, which will not be practical.

Reg.'s
Yucel


On Mon, Jun 10, 2019 at 6:54 PM Templin (US), Fred L <
[e-mail]> wrote:

> Two points I pulled out of the many points that were made were that 1)
> prefixes that are
> overly long can be trivially enumerated by an attacker, and 2) prefixes
> should be aligned
> on nibble boundaries.
>
> I really resonate with point 1), and with Host Address Availability
> (RFC7934) we see that
> it is good to allow hosts (nodes) to configure many IPv6 addresses -
> perhaps even very
> many. I agree with the points that there are already vast numbers of /64s
> available for
> delegation, and /64 has many nice properties including RFC7934 support and
> intractable
> address enumeration. But, if we want to go longer than /64 and still
> satisfy those
> properties, how long would that be - /96?
>
> Point 2) I am not as sure on. Why is it important for prefixes to land on
> even nibble
> boundaries? I can easily delegate a /63 today for example, and I don't see
> anything
> wrong with that. Are we saying that that should be disallowed?
>
> Fred
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