Re: Detailed review of Significance of IPv6 Interface Identifiers

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

On 15/08/2013 10:56, Fred Baker (fred) wrote:
> On Aug 14, 2013, at 2:27 PM, Brian E Carpenter <[e-mail]> wrote:
> 
>>> * Section 3:
>>>> To the extent that each method of IID creation specifies the values 
>>>> of the "u" and "g" bits, and that each new method is carefully 
>>>> designed in the light of its predecessors, these bits tend to reduce 
>>>> the chances of duplicate IIDs.
>>> Not sure what you mean. Do you mean that *if* each IID-generation method
>>> were to use a different combination of "ug", colisions between them
>>> would be avoided? If so, I'd argue that since there's no coordination of
>>> which combinations should be used for which method, that's unfeasible.
>>> For instance, traditional SLAAC uses all combinations (modulo
>>> "illegal/unused" combinations of ug).
>> The argument is fuzzy and the sentence needs to be rewritten.
>>
>> (I would actually suggest that in a pseudo-random method, now that we
>> are clear that the bits have no meaning, it would be best to use them to
>> provide two more bits of entropy rather than giving them fixed values.)
> 
> Good grief. If the bits don't mean anything - and they never did, since nobody ever interpreted them except in IETF dancing-on-heads-of-pins discussions - could we simply say that they are as random in value as any of the other bits in the IID are?

Yes, I believe future IID formats could do that. We can try to make that
clear in the next version.

   Brian