RE: [EXTERNAL] Re: 64bit MAC addresses and SLAAC

Fernando, I think an unspoken assumption in these past several messages is that
privacy is ALWAYS a required property. However, there are cases where address
privacy is not only not required, but it is also desirable and useful to be able to
track a node by a stable and unchanging IP address or prefix.

This is not intended to challenge the non-use of MAC addresses in Interface
Identifiers per your documents, but just to say that in some environments the
randomization and constant changing of IP addresses may actual run counter to
operational objectives.

Thanks - Fred

> -----Original Message-----
> From: ipv6 [mailto:ipv6-bounces@ietf.org] On Behalf Of Fernando Gont
> Sent: Wednesday, June 17, 2020 8:21 AM
> To: Alexandre Petrescu <alexandre.petrescu@gmail.com>; Bob Hinden <bob.hinden@gmail.com>
> Cc: IPv6 List <ipv6@ietf.org>
> Subject: [EXTERNAL] Re: 64bit MAC addresses and SLAAC
> 
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> On 17/6/20 08:39, Alexandre Petrescu wrote:
> > Le 15/06/2020 à 23:01, Bob Hinden a écrit :
> >> Alexandre,
> >>
> >>> On Jun 15, 2020, at 1:23 PM, Alexandre Petrescu
> >>> <alexandre.petrescu@gmail.com> wrote:
> >>>
> >>> Hi,
> >>>
> >>> Before the sanitary situation I was studying an issue at ISO.
> >>>
> >>> The issue is about 64bit MAC addresses and SLAAC.
> >>>
> >>> SLAAC needs a 48bit MAC addresses in order to work, and it can not
> >>> work with a 64bit MAC address; (but yes, it can with 64bit IIDs).
> >>
> >> SLACC does not specify the length of the Interface ID, it does not
> >> require require 48-bit MAC addresses, and the reason for Modified
> >> EUI-64 Format Interface Identifiers in RFC4291 was to support 64bit
> >> EUI-64 Identifiers.   We have since moved away from using MAC
> >> addresses as Interface IDs.  See RFC 8064.
> >
> > Bob,
> >
> > RFC8064 says "this document [...] recommends against embedding stable
> > link-layer addresses in IPv6 Interface Identifiers".
> >
> > But a 64bit MAC address could be a random number as well, not
> > necessarily stable.  Windows randomizes some of its MAC addresses.
> 
> Reusing IDs in multiple contexts is known to be a bad idea. See e.g.:
> https://tools.ietf.org/html/draft-irtf-pearg-numeric-ids-generation and
> https://tools.ietf.org/html/draft-gont-numeric-ids-sec-considerations
> 
> Thanks,
> --
> Fernando Gont
> SI6 Networks
> e-mail: fgont@si6networks.com
> PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
> 
> 
> 
> 
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