Re: [Int-dir] Intdir early review of draft-ietf-ipwave-ipv6-over-80211ocb-34 - 'conforming IPv6' - fe80::/10 vs fe80::/64

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

On 08-Apr-19 21:18, Alexandre Petrescu wrote:
> 
> Le 04/03/2019 à 12:24, Pascal Thubert a écrit :
>> Reviewer: Pascal Thubert
>> Review result: Not Ready
> [...]
>> "
>>
>> This
>>     subnet MUST use at least the link-local prefix fe80::/10 and the
>>     interfaces MUST be assigned IPv6 addresses of type link-local.
>> "
>> If this is conforming IPv6 then the MUST is not needed.
> 
> What do you mean by 'conforming IPv6'?
> 
> The above phrase is a clarification of existing IPv6 specs.
> 
> The spec in question is RFC 2464.  I consider that to be what we need to 
>   conform to.  That spec says 'fe80::/64'.  But that 64 is wrong.  

No it isn't. It specifies the LL prefix used over Ethernet. Since it
is within fe80::/10, it's valid.

I also don't understand the meaning of "at least" in this sentence.

> Hence 
> the clarification.

If you specify the prefix as /10, you have to define how the other 118
bits are constructed. Specifying how the final 64 bits are constructed
is insufficient.

Also, it seems to me that you should cite RFC8064 everywhere that you cite
RFC2464, since the EUI-64 mechanism is now considered obsolete. I also think
the citation of draft-hinden-6man-rfc2464bis is confusing, since it seems
to be comatose.

> 
> Do you disagree with it?
> 
> (the reasons why I put there /10 and not /64 are the following: LLs work 
> in linux with any length between 10 and 64, the ND spec does not 
> restrict to 64,

No, but IPv6-over-foo documents usually do apply that restriction, rather
than define 118-bit IIDs.

      Brian

> the IANA starts at 10, and probably other reasons; there 
> is a recent I-D about this LL prefix length: 
> draft-petrescu-6man-ll-prefix-len-07).
> 
> Alex
> 
>