Re: 6MAN WG Last Call: draft-ietf-6man-predictable-fragment-id-01

[Fernando Gont <[e-mail]>]

On 12/19/2014 04:19 PM, Brian E Carpenter wrote:
> 
> On 20/12/2014 05:45, Fernando Gont wrote:
>> On 12/19/2014 09:52 AM, Brian Haberman wrote:
>>>> That said, I'm not sure I follow what you say above. This
>>>> document has a requirement that the IP ID must not be
>>>> predictable, and
>>>
>>> How does one determine a value is not predictable?  How would the 
>>> predictability of the IP ID value affect interoperability?
>>>
>>> Nothing that I see in this document impacts interoperability.
>>
>> So... does that mean that the only kind of requirements that we can
>> issue in protocol specs are those that affect interoperability?
> 
> There are precedents the other way, for example RFC 4941 specifies
> algorithms for pseudo-random IIDs at SHOULD level, and RFC 7217 has a
> MUST. But for the flow label (RFC 6437), we chose not to specify an
> algorithm; we just specified that the values SHOULD be chosen from a
> uniform distribution.

That was exactly my point. Actually, IMHO it would be too bad to only
focus on the interoperability implications and just ignore the security
aspects.

Thanks,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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