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

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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