Re: [homenet] Ben Campbell's No Objection on draft-ietf-homenet-hncp-09: (with COMMENT)

["Ben Campbell" <[e-mail]>]

On 20 Nov 2015, at 1:30, Markus Stenberg wrote:

> On 18.11.2015, at 17.02, Steven Barth <[e-mail]> wrote:
>>> -6.4, first paragraph: "Each HNCP node SHOULD announce an IPv6 
>>> address
>>> and - if it supports IPv4 - MUST announce an IPv4 address,"
>>> I don't suppose there's any way we can make IPv6 a MUST?
>> I guess we could unify both and make them both SHOULD or MUST. Right 
>> now
>> I can't really remember the argument for or against either but I will
>> discuss it with Markus.
>
> This current MUST + SHOULD is actually result of developments during 
> summer (not sure if it was this summer, but I suspect so). Note that 
> it does NOT say that you MUST assign IPv4 and SHOULD assign IPv6; it 
> talkes entirely about announcing the said assignment. The assignment 
> is also used for conflict resolution, but (at the time) the people who 
> discussed these noted that RFC7217 is unlikely to conflict, and 
> therefore announcing the assignments is nice to have, but not 
> mandatory (and you could also use e.g. DAD if you really wanted to as 
> this is simply local state on a link). In case of IPv4, where we 
> essentially pick out of /26, 1 in 64 chance of collision (1 in ~8 due 
> to birthday paradox) was not considered as good odds and therefore it 
> was made a MUST; there is no IPv4 DAD as fallback either.
>
> I am not fine with SHOULD for IPv4 as it will essentially break it; I 
> can live with MUST for IPv6 but consider it unneccessary. Let me know 
> how you feel about it (or if we should add the justification text to 
> the document).

Your answer makes perfect sense. My wishful thinking was just wishful.

Ben.

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