Re: Feedback on draft-gont-6man-stable-privacy-addresses-01 (was: Re: Consensus call on adopting:....)

Washam Fan <> Sat, 14 April 2012 06:25 UTC

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Date: Sat, 14 Apr 2012 14:24:44 +0800
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Subject: Re: Feedback on draft-gont-6man-stable-privacy-addresses-01 (was: Re: Consensus call on adopting:....)
From: Washam Fan <>
To: Karl Auer <>
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>> > 5: Duplicate address detection is not mentioned explicitly, but probably
>> > should be - what happens if a host does DAD and determines that its
>> > stable address is already in use?
>> Address configuration fails.
> That should be in the spec.
>> That said, if deemed appropriate, one could include one additional byte,
>> "DAD" in the hash function, which is initialized to 0, and that is
>> incremented by 1 if the host wants to try a different address if/when
>> DAD fails.
>> If we do that, the implementations should probably cache the resulting
>> address, such that it is stable. (otherwise the resulting address might
>> change if the same node was brought up while the node with the
>> conflicting address is off).
> This may not be possible on systems with no onboard storage, and makes
> things much more complicated.

+1. And the storage or filesystem could have been damaged.

> I suggest that if DAD fails, then
> autoconfiguration should just fail (at least as regards stable
> addresses).
So what is the next step if the autoconfiguration fails? static
configure? If yes. Will the next reboot try autoconfiguration again?
If yes, you may have non-stable addresses within the same network. If
no, when you move to another network you should explicitly revoke the
static configuration and enable autoconfiguration again.

I think the author should clarify this DAD failure issue in the next version.