On 04/02/2013 07:52, sth...@nethelp.no wrote:
>> I can find many reasons to remove the magic from the U and G bits. I
>> personally ran into the U/G bit issues in RFC 4380 (Teredo) and RFC 6052
>> (IPv4-embedded IPv6 addresses). In both cases, the design would have been
>> simpler if we had not try to maintain the fiction of the U and G bits. And
>> CGA could definitely benefit from 2 additional bits of entropy. So this is
>> not a change "just because."
>
> Fully agreed.
>
> Another point in favor of removing the magic: RFC 4291 explicitly says
>
> "For all unicast addresses, except those that start with the binary
> value 000, Interface IDs are required to be 64 bits long and to be
> constructed in Modified EUI-64 format."
>
> but later in the same chapter says
>
> "IPv6 nodes are not required to validate that interface identifiers
> created with modified EUI-64 tokens with the "u" bit set to universal
> are unique."
>
> And indeed, on the routers where I have tried, I am able to configure
> static IPv6 addresses with no regard to the u/g bits.
>
> In other words, any special meaning of the u/g bits is just fiction -
> there is no enforcement or guarantee of any kind.
Right. The draft may be clumsily expressed so far, but that is the point.
I think we know how we have to improve the draft to make these things
more clear. Please give us a little time, since my co-author is on vacation
for the Chinese New Year holidays.
Brian
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