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

[Alexandre Petrescu <[e-mail]>]

Le 17/06/2020 à 18:17, Templin (US), Fred L a écrit :
> 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:[e-mail]] On Behalf Of Fernando Gont
>> Sent: Wednesday, June 17, 2020 8:21 AM
>> To: Alexandre Petrescu <[e-mail]>; Bob Hinden <[e-mail]>
>> Cc: IPv6 List <[e-mail]>
>> Subject: [EXTERNAL] Re: 64bit MAC addresses and SLAAC
>>
>> This message was sent from outside of Boeing. Please do not click links or open attachments unless you recognize the sender and
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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
>>>>> <[e-mail]> 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

Using same IIDs in several interfaces might be a bad idea some times but 
good elsewhere.

For example, when I am manually configuring two interfaces of the same 
router it is easy for me to know I just need to change one or two hex 
digits in the subnet number.  It is much faster.

It is a matter of convenience to humans, in some contexts.

Alex

>>
>> Thanks,
>> --
>> Fernando Gont
>> SI6 Networks
>> e-mail: [e-mail]
>> PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
>>
>>
>>
>>
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