[dhcwg] Re: New draft: DHCPv6 Recommended IPv6 Address Opt ion

Thank you for the feedback, Lorenzo.  I agree we need to be more clear
about the lifetimes.
I've pushed a -01 which incorporates this as well as your other feedback,
such as adding a use-case/applicability section:

https://author-tools.ietf.org/iddiff?url1=draft-nygren-dhc-recommended-ipv6-address-00&url2=draft-nygren-dhc-recommended-ipv6-address-01&difftype=--html

Best, Erik


On Thu, Jul 3, 2025 at 4:40 PM Lorenzo Colitti <[email protected]> wrote:

> I read the draft and it seems useful for clients that implement DHCPv6 PD.
>
> I noticed that there is no mention of the lifetimes of the addresses, or
> how they are renewed. From reading the text I'd guess that addresses have
> exactly the same lifetimes as the prefix that encloses them, but it seems
> that the draft should explicitly say that.
>
> It would probably make sense for the draft to say when networks should use
> this option instead of IA_NA. Your email mentions that this option avoids
> the need for separate FIB entries for the IA_NA and IA_PD. Presumably
> another reason would be that it simplifies client code, because the client
> does not need to manage the lifetimes of and renew the address(es)
> independently from the prefix. I'd guess maybe it's possible that there are
> clients that don't implement IA_NA.
>
> It occurs to me that this could be used for IPv6 CE routers as well. CE
> routers always need to run DHCPv6 PD, and ISP-managed CE routers
> additionally need to use IA_NA to get an address on which they can be
> managed. This option could be used instead.
>
> On Thu, Jul 3, 2025 at 8:46 PM Erik Nygren <[email protected]> wrote:
>
>> Following some discussions at past IETFs, I've created a -00 draft for a
>> new "DHCPv6 Recommended IPv6 Address Option".
>> Abstract:
>>
>>    This document defines a new DHCPv6 option for communicating one or
>>    more recommended /128 IPv6 address to hosts within an assigned
>>    prefix.  The Recommended Address option allows DHCPv6 servers to
>>    suggest specific IPv6 addresses that hosts should additionally use
>>    when configuring addresses within the assigned prefix.
>>
>> Github:
>> https://github.com/enygren/draft-nygren-dhc-recommended-ipv6-address
>> HTMLized:
>> https://datatracker.ietf.org/doc/html/draft-nygren-dhc-recommended-ipv6-address
>>
>> The primary use-case for this is hosting, datacenter, and cloud
>> environments that want to assign a /64 per host but which also want to
>> ensure the host configures one or more addresses (such as for management
>> and running services).  Operators configuring servers in these environments
>> want to be able to ensure that a host will be available on a given /128
>> (for ssh'ing into, putting into DNS as a service endpoint, etc) while
>> DHCPv6-PD also means that the host is free to use the rest of the /64 for
>> its own purposes (eg, containers, K8s pods, temporary addresses, etc).
>>
>> Using both IA_PD and IA_NA separately could also meet this use-case, but
>> would require multiple FIB entries or would effectively mean assigning a
>> /63 per host.  Using PD_EXCLUDE and then IA_NA within the PD_EXCLUDE prefix
>> was another alternative, but seems messier, more fragile, and outside my
>> understanding of the intent of PD_EXCLUDE.
>>
>> I'd be happy to discuss in Madrid, either in hallways or presenting to
>> the DHC, v6ops, and/or 6man WG(s) if time is available.  It was suggested
>> that DHC would be the best venue to pursue this draft, but I'm open to
>> alternatives.
>>
>> Best,
>>
>>         Erik
>>
>>
>> ---------- Forwarded message ---------
>> From: <[email protected]>
>> Date: Thu, Jul 3, 2025 at 3:26 PM
>> Subject: New Version Notification for
>> draft-nygren-dhc-recommended-ipv6-address-00.txt
>> To: Erik Nygren <[email protected]>
>>
>>
>> A new version of Internet-Draft
>> draft-nygren-dhc-recommended-ipv6-address-00.txt has been successfully
>> submitted by Erik Nygren and posted to the
>> IETF repository.
>>
>> Name:     draft-nygren-dhc-recommended-ipv6-address
>> Revision: 00
>> Title:    DHCPv6 Recommended IPv6 Address Option
>> Date:     2025-07-03
>> Group:    Individual Submission
>> Pages:    8
>> URL:
>> https://www.ietf.org/archive/id/draft-nygren-dhc-recommended-ipv6-address-00.txt
>> Status:
>> https://datatracker.ietf.org/doc/draft-nygren-dhc-recommended-ipv6-address/
>> HTML:
>> https://www.ietf.org/archive/id/draft-nygren-dhc-recommended-ipv6-address-00.html
>> HTMLized:
>> https://datatracker.ietf.org/doc/html/draft-nygren-dhc-recommended-ipv6-address
>>
>>
>> Abstract:
>>
>>    This document defines a new DHCPv6 option for communicating one or
>>    more recommended /128 IPv6 address to hosts within an assigned
>>    prefix.  The Recommended Address option allows DHCPv6 servers to
>>    suggest specific IPv6 addresses that hosts should additionally use
>>    when configuring addresses within the assigned prefix.
>>
>>
>>
>> The IETF Secretariat
>>
>>
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>

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