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 >>> ipv6@ietf.org >>> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 >>> -------------------------------------------------------------------- >> >> ---------------------------------------------------- >> The ignorance of how to use new knowledge stockpiles exponentially. >> - Marshall McLuhan >> >> -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
