2012-12-19 21:27, "Bless, Roland (TM)" <[email protected]> :
> Hi Rémi, > > On 19.12.2012 18:59, Rémi Després wrote: > >> As is, the sentence misses that IIDs that have u=1 are expected to be >> universally unique. (This uniqueness is key to ensure that, as long > > I don't agree. From an IPv6 functional point of view, IIDs only need to > be unique within the link-local/subnet scope, so _universal_ uniqueness > is not strictly _required_. Deriving the IID from a universally unique > address may help to minimize the conflict probability within a subnet > though. 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. At the IP layer, it has also been effective to support a good level of address stability without needing manual configurations. >> as a site has a stable IPv6 prefix, its statelessly auto-configured >> hosts can have stable addresses if so desired.) > > You can also achieve the mentioned uniqueness of an IPv6 address by > having manually assigned locally unique IIDs (which is typically used > for servers since you don't want to change the IPv6 address each time > your network interface must be replaced due to hardware problems...) > combined with that stable (globally unique) IPv6 prefix. Address stability is useful for servers, yes, but also for referrals, and in general when addresses are advertised in various ways. 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. >> Ensuring IID universal uniqueness for new types of universal-scope >> addresses is the subject at hand. It can fortunately be dealt with >> because we know that, today, all u=1 IIDs must also have g=0. > > 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. Regards, RD > > Regards, > Roland -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
