default IID mechanism (was Re: macos Sierra with CGA address?)

Brian E Carpenter brian.e.carpenter at
Fri Dec 16 01:09:00 CET 2016

On 16/12/2016 00:12, Holger Zuleger wrote:
>>> My info is, to set
>>> 	sysctl -w net.inet6.send.opstate=0
>>> to go back to mac address based eui64, but didn't checked it.
>> Please don't resort to eui64. That's a bad idea. See RFC7721 and RFC707
> Hmm, yes but from an operating view...
> In case of re-numbering your network, RFC72177217 (and SEND as well) is
> a step backward. Both EUI48 and the Windows random stable IID mech have
> the benefit of prefix independent IIDs.
> The change of name to IP mapping in the DNS is ways easier if the IID
> remain the same. I have a small programm to re-generate additional AAAA
> records if I have to introduce a new provider prefix (and delete the old
> one as well).
> If the IID is prefix dependent (CGA, RFC7216), than the best (or the
> only scalable way) is that the host itself updates the DNS via dynamic
> updates.
> And integrating dynamic dns into standard operating systems is another
> thing I'm  waiting for a long time now.

Using Dynamic DNS Update for this has been recommended since RFC4192 in
2005. We renewed that in .
If many operators yell for it, it might even happen.


> BR
>  Holger

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