Re: [v6ops] [dhcwg] IPv6-Only Preferred DHCPv4 option

[Mark Smith <[e-mail]>]

On Thu, 5 Dec 2019 at 11:30, Roy Marples
<roy=[e-mail]> wrote:
>
> Hi Jen!
>
> I maintain dhcpcd, a fairly popular DHCP and DHCPv6 client.
>
> On 04/12/2019 12:09, Jen Linkova wrote:
> > One of the biggest issue in deploying IPv6-only LANs is how to do it
> > incrementally, when some hosts work just fine in NAT64 environment
> > while some legacy devices still need IPv4. Doubling the number of
> > network segments (having an IPv6-only and dual-stack segments of each
> > type) is an operational nightmare. So it would be just awesome if all
> > devices can co-exist in the same network segment and hosts capable of
> > operating in IPv6-only environment do not consume IPv4 addresses.
> > So here is the draft proposing a new DHCPv4 option to help saving IPv4
> > addresses and deploying IPv4-as-a-service:
>
> I disagree with a fair chunk of this.
> It assumes that IPv6 is the be-all and end-all. Maybe one day we will
> have IPv8?
>

Going by the now almost entire lack of existence of Appletalk, IPX,
DECNET, XNS, VINES (I haven't seen or heard of any of them in a
network since 1999),  it's likely IPv6 will be the single network
layer protocol in the future. Running a single network layer protocol
is cheaper and easier, which is why those others have gone away (that
also explains why nearly all links use or emulate (Wifi) Ethernet
framing, unless they specifically can't).

IPv6 will have a life, just as IPv4 has had a life, and those other
past protocols have had a lives. IPv6 is designed to last for much
longer than almost any of them, centuries most likely, so I don't
think we shouldn't be worrying about accommodating "IPv8" now at the
cost of making IPv4 easier to move away from. We don't have any idea
what "IPv8"'s transition requirements are or what it will even look
like.

> It would be much better to say that DHCP as a whole is disabled.
> See RFC 2563 for an equivalent DHCP option for IPv4LL. This is fair
> enough because it's all IPv4 addresses. Set both options and you're golden.
>
> BUT - what if we need to enable DHCP again? Should clients still listen
> for FORCERENEW? It does pose a small dilema because there isn't actually
> anything to renew.
>
> So maybe we could let this new option fit in with T1 and T2 timers
> (well, effectively T2 as there's no address to unicast from) and you can
> even set this to infinity if you wanted to.
>
> Roy
>
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