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

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

I'm replying selectively in this thread to avoid repetition. So:

On 13/06/2017 20:18, Lorenzo Colitti wrote:
> On Sun, Jun 11, 2017 at 8:37 AM, Brian E Carpenter <
> [e-mail]> wrote:
> 
>> This has two aspects for me:
>> 1) It's simply out of place to define an arbitrary constant
>> in something called "architecture".
>>
> 
> Er, what? It's perfectly fine to say that the address is 128 bits long, and
> that half of it is assigned to the network and half to the link.

But it doesn't. It first states that the boundary between prefix
and IID is floating, and then states that it isn't.

>> 2) By defining it globally we forbid using some other value
>> on a future link-layer where a different value might be better.
>> A 'should' could cover that, of course, which is why I accept
>> the current 4291bis text.
>>
> 
> I don't see why we need new text for that. Any document that wants to use a
> different value can simply update 4291.

Agreed, theoretically. But simply s/required/recommended/ in 4291bis
would be a much more elegant way of handling this.
 
>>> I am still confused what this draft proposes to change.
>>
>> Nothing in any current implementation.
> 
> 
> We have a popular implementation that only accepts 64-bit IID lengths in
> certain cases. Are you proposing that our implementation change or not?

No. But if some new link technology comes along for which there is a good
technical argument for, say, 60 bit interface identifiers, wouldn't you
want to accommodate it? (I have no idea what that argument might be.)

    Brian