Le 2014-04-17 17:14, Mark Andrews a écrit :
>>>     0 full IPv4 connectivity
>>>     1 all IPv4 off on the interface
>>>     2 local (link/site not global) connectivity only on the interface
>>>     3 no IPv4 on the machine.
>>
>> Uh, no. The levels are in strictly increasing order. 2 includes
>> everything in 1, plus some more:
>>
>>    2 - No IPv4 upstream, local IPv4 restricted:  Same semantics as value
>>       1, with the following additions:
>>
>> 2 deals with propagation to downstream interfaces. It has nothing to do
>> with link or site local stuff.
> 
> Part of the problem here is that "upstream" is the only "interface"
> for singlely attached devices other than loopback.  There is no
> "only local connectivity is available" step for such nodes.

Correct. For such nodes, 1 == 2. Is that a problem? It's still a
stairway going up, with steps 1 and 2 being at the same height for a
subset of nodes.

Simon

> 
>    0 - IPv4 fully enabled:  This is equivalent to the absence of the No-
>       IPv4 option.  It is included here so that a DHCPv6 server can
>       explicitly re-enable IPv4 access by including it in a Reply
>       message following a Reconfigure, or similarly by a router in a
>       spontaneous Router Advertisement.
> 
>    1 - No IPv4 upstream:  Any kind of IPv4 connectivity is unavailable
>       on the link on which the option is received.  Therefore, any
>       attempts to provision IPv4 by the host or to use IPv4 in any
>       fashion, on that link, will be useless.  IPv4 MAY be dropped,
>       blocked, or otherwise ignored on that link.
> 
> Mark


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