On 13/01/2017 12:26, Randy Bush wrote:
>>> but i am having a hard time reconciling 2.4.4's insistence on a
>>> mandatory 64-bit uuid in all unicast global addresses with 2.4.0, rfc
>>> 6141, widespread operational practice, ... clue bat please.
>>
>> This was discussed extensively in 6MAN and resulted in RFC7421
>> "Analysis of the 64-bit Boundary in IPv6 Addressing”. The text in
>> rfc4291bis is:
>>
>> For all unicast addresses, except those that start with the binary
>> value 000, Interface IDs are required to be 64 bits long.
>> Background on the 64 bit boundary in IPv6 addresses can be found in
>> [RFC7421].
>
> thanks for the review that the wg came to this decision in conflict with
> operational practice and its own statement in 2.4.0. i did read the
> documents.
>
> since it is incorrect, ietf last call seems to be the time to fix it.
>
> to be clear, i have no problem with iids being 64-bit. my issue is with
> unicast globals being classful in 2.4.4.
RFC7421 (which is Informational) calls out RFC 6164 (not 6141!) as an exception.
To be precise it says:
The de facto length of almost all IPv6 interface identifiers is
therefore 64 bits. The only documented exception is in [RFC6164],
which standardizes 127-bit prefixes for point-to-point links between
routers, among other things, to avoid a loop condition known as the
ping-pong problem.
I would suggest adding a similar exception statement in 4291bis.
Brian