2013-02-06 00:45, Doug Barton <do...@dougbarton.us> : > On 02/05/2013 05:57 AM, Rémi Després wrote: >> Hi, Doug, >> >> Please see inline. >> >> >> 2013-02-04 à 18:37, Doug Barton <do...@dougbarton.us> : >> >>> On 02/04/2013 12:38 AM, Rémi Després wrote: >>>> It remains that IIDs having u=1 SHOULD be unique, i.e. with rare enough >>>> exceptions. This is somewhat similar to the expectation that ULA >>>> collisions shouldn't be seen). >>>> >>>> This theoretical unicity has been extensively used to assign stable IIDs, >>>> without administrative action, to hosts that have no privacy constraints >>>> requiring the opposite. >>> >>> What software exists that makes determinations based on the u bit? >> >> (*) Major OSes can assign IIDs derived from IEEE MAC addresses of their LAN >> adapters (if not by default, at least as a possibility). They do it because >> of what IEEE and IETF have specified, each one for its own domain, >> concerning their respective u bits. > > Yes, you've described reality. You haven't answered my questions.
Fair enough. My answer is that no software that I know makes determination based on the u bit. My point is that it isn't sufficient for the IETF u bit to have no meaning. (a) It has what is specified in RFC 4291. (b) No software I know creates IIDs having u = 1 without an IEEE-based OUI. QUESTION: Do you know one? >> With these specifications, it is impossible on a SLAAC link that two hosts >> that have universal-scope addresses (necessarily different if they >> communicate at the MAC layer), would have conflicting IIDs at the IP layer >> if they derive them from MAC addresses. > > What makes the addresses unique are the unique MACs, not the u bit. No disagreement on this. > >>> How would that software be impacted if the u bit were suddenly be devoid of >>> meaning? >> >> Hosts would become free to assign arbitrary IIDs having u=1, breaking >> applicability of (*) above. > > Faulty premise -> faulty conclusion. This gets too subtle for my ability to understand which premises and which conclusion you talk about. Let's go to basics. Are you suggesting to CHANGE the u bit significance? - If no, no disagreement is IMHO worth debating - If yes, we have indeed different opinions. See below. > >>> I am of course assuming that DAD would still be in play for dynamically >>> assigned addresses, which it seems we are all in agreement on. >> >> Sure (agreement confirmed). >> >> >> Hope it clarifies. > > To me, it clarifies that you don't have answers to my questions. I have now answered the ONLY remaining question from you I have noticed. Your turn to answer mine. > Given that you cannot demonstrate any negative impact to un-defining the u > bit, I wonder what the basis of your objection is. The logic is the reverse. Before changing a standard, one needs to demonstrate it is indispensable. QUESTIONS: (a) Which sentences of RFC 4291 you think MUST be changed? (b) Why? Please give your personal answers (not by reference to comments made by someone else). Thanks, RD > > Doug > -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------