> From: Robert Elz <[EMAIL PROTECTED]> > > | The main fact is that my version is just an implementation based on > | the autoconfigure RFC, taking the allowed DAD optimization (= do DAD > | on link-local, combine id with announced prefixes without doing DAD on > | those combinations). > > The problem is that this only works if no-one is allowed to create > addresses that don't have link local - otherwise the order in which > the addresses are created makes a race condition wrt DAD.
It can be made to work, if those who want to define addresses without corresponding link local, take care of not tresspassing the addresses generated by autoconfigure process. I listed some examples of approaches. "DIID" or equivalent is one possible apporach, but I'm not proposing proposing that. I just want to keep the autoconfigure DAD optimization as allowed. Other address configuration MUST take that into account. > Obviously you can define "abnormal" so as anything affected fits, but > certainly KAME (and I suspect Microsoft) would need to change, as it > allows addresses that aren't based upon a LL address to be defined. Yes, my stack allows defining any address manually. I don't code programs that pretend to be more clever than the user. I assume if the user wants some specific address, then he/she will get it (if it passes DAD). In manual configuration I assume user KNOWS from that the address will not collide with autoconfigured (as a root you can always shoot your foot). > Such addresses are subject to DAD, so that's OK, they won't be duplicates, > but the IID part isn't defended against attempts to re-use it in other > addresses (different prefix). I'm not proposing defending plain ID part (that is just an option that is available). > On the other hand, DIID forbids subnets being merged into one link, if > they happen to have nodes assigned with the same IID (like "1"). There > is no problem with uniqueness of the addresses, the prefixes differ, but > because the IIDs don't, DIID would prohibit them from being used on the > same link. If you have two subnets with different prefixes. Apparently you then have a router on both subnets which announce their prefixes. When you merge the subnets, ALL nodes will see both routers and will autoconfigure both prefixes with all of their addresses. Yes, in this case if two nodes happen to have same id, doing DAD on all addresses would detect the collision. But, you are hosed anyway, as those same nodes are also using the same link local address (they have same id, they are on same link => both have fe80::id, and Neighbor discovery breaks totally for them...). -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
