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

[Roy Marples <[e-mail]>]

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?

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