On 19/12/2012 01:16, Joel M. Halpern wrote:
> Phrased that way, I do not think any stack anywhere looks at the U or G
> its in a received IPv6 address.
That's why I asked if ILNP depends on the u bit. You presumably
saw Ran's reply, including "The U bit does have value for ILNP."
> I have no problem if we declare hem to be irrelevant.
If we could, IMHO it would be a step forward. But that needs
a debate.
Brian
>
> Your,
> Joel
>
> On 12/18/2012 8:13 PM, Fred Baker (fred) wrote:
>> As you know, the EUI-64 address is but one of the seeds that an EID
>> can be generated from. Having been generated, it's a bit string, and
>> another bit string either equals it or doesn't.
>>
>> You didn't answer my question.
>>
>> What, on an IPv6 host or router, cares about the g bit apart from the
>> code that uses an EUI-48 or EUI-64 to create an EID? What starts from
>> an EID and extracts from it an EUI-64/48 address, or in any other way
>> interprets the g flag in an EID?
>>
>> u and g are a recurring theme. Apart from the people who wrote RFC
>> 4291, who are under the delusion that the only link layer in the world
>> is an Ethernet, who actually cares?
>>
>> On Dec 18, 2012, at 5:06 PM, Joel M. Halpern wrote:
>>
>>> As I understand it, the original intent with the U bit was to provide
>>> an easy way to create IID that were highly likely to be distinct from
>>> all other IIDs (on the link). As IEEE reserves the G bit, we marked
>>> that as special as well when the U bit was set.
>>>
>>> Changing the meaning of U=1, G=0 seems a major chane with no
>>> particular benefit.
>>>
>>> When we defined it, we were unclear about the U=1, G=1 case. Given
>>> the way the U bit is defined, U=1, G=1 can not occur in the normal
>>> course of events. We can ignore it. we can define it. We can
>>> reserve it and thn sit on our hands. But given taht we have text
>>> already, and that text is ambiguous, it seems like we should at least
>>> clear up the ambiguity.
>>>
>>> Yours,
>>> Joel
>>>
>>> On 12/18/2012 7:35 PM, Fred Baker (fred) wrote:
>>>> Why do we care about u and g in the first place? Is there code in an
>>>> IPv6 router or host that interprets them?
>>>>
>>>> On Dec 18, 2012, at 3:50 PM, Joel M. Halpern wrote:
>>>>
>>>>> In reading the discussion,a nd trying to think through what I
>>>>> understand to be correct, it seems that there is an unforeseen
>>>>> ambiguity in the way the current documents about IPv6 IIDs are
>>>>> written.
>>>>>
>>>>> I think that there are two possible meanings, ad we should decide
>>>>> explicitly which one we want.
>>>>>
>>>>> 1) u=1 means that the IID is derived from an IEEE OUI (of some
>>>>> form). With that meaning, u=1, g=1 is clearly some sort of
>>>>> multi-entity identifier. And we should say that somewhere.
>>>>>
>>>>> 2) u=1, g=1 was unforeseen, and we don't know what it means. In
>>>>> that case, we ought to figure out how we want that portion of the
>>>>> IID space used, and write it down clearly. It seems to me that
>>>>> allowing this space to be used for special-semantic IIDs (with
>>>>> suitable care so that the entire ecosystem is not affected by them)
>>>>> is a very reasonable path.
>>>>>
>>>>> It seems unlikely that there is actual practice in the wild with
>>>>> u=1, g=1 under either interpretation. We do now have a request to
>>>>> start using it (4rd). So we should decide.
>>>>>
>>>>> Yours,
>>>>> Joel
>>>>> --------------------------------------------------------------------
>>>>> IETF IPv6 working group mailing list
>>>>> [email protected]
>>>>> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
>>>>> --------------------------------------------------------------------
>>>>
>>>> ----------------------------------------------------
>>>> The ignorance of how to use new knowledge stockpiles exponentially.
>>>> - Marshall McLuhan
>>>>
>>>>
>>
>>
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