On 05/02/2013 14:11, Rémi Després wrote: > Le 2013-02-05 à 15:01, sth...@nethelp.no a écrit : > >>> 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. >> Impossible if the MAC addresses are indeed unique. That is correct for >> *almost* all cases. But not 100%. > > They are different 100% of cases at the IP layer if they are different at the > MAC layer (which is needed for communication at this layer). > OK?
Not if the same MAC address appears on two different subnets in the same site. This would work from a conventional IPv6 point of view, but it would immediately demonstrate that the u bit does not mathematically guarantee uniqueness. There has been discussion recently in MIF of scenarios where the same IID would appear intentionally on different interfaces of the same device. It is not the process of generating IIDs that is a problem - that is well defined. It is assuming after they have been generated that the u/g bits have meaning that is problematic. (Which is also why the solution of a reserved range makes sense for 4rd.) Brian -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
