Re: IPv6 Routing & ND vs. Addressing, (Was: Re: <draft-ietf-6man-rfc4291bis-09.txt>)

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

On 13/07/2017 01:53, Lorenzo Colitti wrote:
> On Wed, Jul 12, 2017 at 11:39 AM, Brian E Carpenter <
> [e-mail]> wrote:
> 
>> The advantage of requiring or recommending 64 bits is that it avoids the
>> debate about N. I prefer 'recommend' because it avoids enumerating all
>> possible exceptions. We've seen how hard it is to wordsmith the exceptions.
>>
> 
> What's hard is not wordsmithing the exceptions.
> 
> What's hard is claiming that there's consensus (even rough consensus). The
> fact of the matter is that we have opposing camps with equally strong
> opinions on the matter, and neither camp is willing to accept the position
> of the other.
> 
> Based on past experience, it seems pretty clear to me that this situation
> will not change until we get a problem statement that we agree on. Care to
> write one up?
> 

Nick Hilliard just did:

>> I would suggest that future protocols need to define what makes sense
>> for them, and mandating a constant in advance isn't necessary or even
>> appropriate.

Which is why I personally would be happy with the addressing
architecture either not mentioning 64 at all, or *recommending* 64,
or requiring 64 "except if the first three bits
of the address are 000, or when the addresses are manually
configured, or by exceptions defined in standards track documents."

IMHO any of those three formulations would resolve Nick's problem
statement (given that there is also a citation of BCP198 in the
latest draft to clarify how routing works).

    Brian