Re: draft-bourbaki-6man-classless-ipv6-00

[Brian E Carpenter <[e-mail]>]

On 09/06/2017 19:46, [e-mail] wrote:
> 
>> On 6 Jun 2017, at 00:25, Brian E Carpenter <[e-mail]> wrote:
>>
>> On 05/06/2017 19:45, Lorenzo Colitti wrote:
>>> On Mon, Jun 5, 2017 at 8:05 AM, Brian E Carpenter <
>>> [e-mail]> wrote:
>>>
>>>> None of that is the point. The point is to establish
>>>> that routing is classless
>>>
>>>
>>> Routing is already classless because BCP 198.
>>>
>>>
>>>> and /64 is a parameter of specific addressing schemes.
>>>>
>>>
>>> It *is* a parameter. The parameter's value is 64 for all unicast addresses
>>> except those starting with 000.
>>
>> The parameter's *current* value, yes. But should we really be fixing
>> the value of the parameter once and for all in the addressing architecture?
>> Why don't we fix it in each IPv6-over-foo, which is what the SLAAC design
>> assumes?
> 
> do we have a rationale for fixing the value in the IPv6-over-foo documents (anymore)?

My rationale is that

a) RFC4862 describes it very carefully as a parameter.
b) The addressing architecture describes it as a parameter ("n"),
and then suddenly defines n=64 for no reason.
c) It gives no reason because the true reason was the obsoleted EUI-64 mechanism.
d) There is no physical reason for n to have the same value on different link media.
e) Future link media might more appropriately use a different value.
f) Therefore the addressing architecture should only define n=64 as a default
recommendation for IPv6-over-foo documents.

    Brian