A crazy idea
randy at psg.com
Mon Jul 19 16:37:14 UTC 2021
On Mon, 19 Jul 2021 09:27:13 -0700,
Nathan Angelacos wrote:
> On Mon, 2021-07-19 at 08:51 -0700, Randy Bush wrote:
> > > Well, for SLAAC you need a /64
> > this is not true
> > randy
> That is cool! Can you point me to the correct RFC please?
from the war zone, draft-classless6/draft-nbourbaki-6man-classless-ipv6
The length of the Interface Identifier in Stateless Address
Autoconfiguration [RFC4862] is a parameter; its length SHOULD be
sufficient for effective randomization for privacy reasons. For
example, 48 bits might be sufficient. But operationally we
recommend, barring strong considerations to the contrary, using
64-bits for SLAAC in order not to discover bugs where 64 was hard-
coded, and to favor portability of devices and operating systems.
Note that OpenBSD ships with SLAAC for lengths longer than /64.
Nonetheless, there is no reason in theory why an IPv6 node should not
operate with different interface identifier lengths on different
physical interfaces. Thus, a correct implementation of SLAAC must in
fact allow for any prefix length, with the value being a parameter
per interface. For instance, the Interface Identifier length in the
recommended (see [RFC8064]) algorithm for selecting stable interface
identifiers [RFC7217] is a parameter, rather than a hard-coded value.
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