Hi Rémi, On 20.12.2012 09:54, Rémi Després wrote: > Interface addresses at the link layer are specified by IEEE to be > universally unique. This has been effective fort link-layer > communication to need neither manual configuration nor a DAD-like > protocol at this layer.
IEEE link layer addresses should be universally unique, but there were cases in which this assumption is not true, esp. if you consider that some manufacturers simply hijacked others OUIs or that most NICs and drivers allow to set nearly arbitrary MAC addresses. Moreover, there are now vast amounts of virtual machines in use that may use non legitimate IEEE addresses. So IMHO one should not rely on supposed universal uniqueness, but always perform DAD to detect conflicts... > At the IP layer, it has also been effective to support a good level > of address stability without needing manual configurations. Yep, however, this is also true for algorithmically derived IIDs as with privacy extensions or CGAs. > Address stability is useful for servers, yes, but also for referrals, > and in general when addresses are advertised in various ways. My point was that statically assigned IIDs may lead to even more stable IPv6 addresses than those generated out of EUI-64s. > Relaxing uniqueness of IIDs that are based on universal-scope EUI-64 > would be a step backward. There is no need AFAIK for such a > regression. I never promoted to "relax the uniqueness of IIDs" (whatever that means), my point was to avoid introducing a certain structure into IIDs. >> what new types of universal-scope addresses? > > One appears now with 4rd. As stated in the note of the draft > submitted to 6man, "Its function is to ensure that 4rd IPv6 addresses > are recognizable by CEs without any interference with the choice of > subnet prefixes in CE sites". These prefixes, as well as IIDs used in > sites that support 4rd may have been chosen before 4rd is activated. Yes, I read that, but it's unclear to me why it would be such a big deal to "reconfigure" the subnet prefixes for 4rd use since you have to activate and configure your box anyway, i.e., maybe you can flag an existing prefix for 4rd use when turning 4rd on. Moreover, would it really be such a big deal to change a subnet prefix when turning 4rd on, since we have auto configuration? BR, Roland -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
