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Re: DHCPv6 address selection option and stateless DHCPv6?

Tim Chown <tjc@ecs.soton.ac.uk> Fri, 06 September 2013 12:22 UTC

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Subject: Re: DHCPv6 address selection option and stateless DHCPv6?
From: Tim Chown <tjc@ecs.soton.ac.uk>
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Date: Fri, 06 Sep 2013 13:23:03 +0100
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To: Lorenzo Colitti <lorenzo@google.com>
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On 6 Sep 2013, at 12:13, Lorenzo Colitti <lorenzo@google.com> wrote:

> Not sure if it's too late to fix this, but I happened to notice this text in draft-ietf-6man-addr-select-opt-11:
> 
> "When the information from the DHCP server goes stale, the policy received from the DHCP server SHOULD be deprecated."
> 
> Unfortunately, as RFC 4076 points out, information received via stateless DHCPv6 never expires. (That's one of the many reasons why DHCPv6... but I digress). What's the intent here?
> 
> 1. This option is not recommended for use with stateless DHCPv6?
> 2. This option can be used with stateless DHCPv6, but its contents never expire?
> 3. This option can be used with stateless DHCPv6, and the client expires it whenever it feels like it?

A good question. It would be desirable not to preclude its use with stateless DHCPv6.  I've not caught up with all IESG comments yet; it may have been raised there also.

> If #2, then perhaps this option needs a lifetime value? Unless the plan is that a) who/whatever solves the problem statement in RFC 4076 will solve this too, or b) that everyone needing this option will use stateful DHCPv6.

What about use of RFC 4242, which SHOULD be supported in IPv6 CE's, for example (as per RFC 6204)?  RFC 4242 was produced to address the problems discussed in RFC 4076.

> Either way, it seems prudent to say something about this in the document, as otherwise it's a bit of a trap for the unwary.

Agreed, and thanks.

Tim

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