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

[Roy Marples <[e-mail]>]

On 05/12/2019 01:00, Jen Linkova wrote:
> While the draft keeps mentioning IPv6-only and NAT64 as a prerequisite
> for disabling IPv4, it's only because it's the only use case exist
> today.
> If I wake up tomorrow to find out that we have IPv2020 and majority of
> my devices can operate on IPv2020-only while I still have to provide
> IPv4 for some hosts, we can do 's/IPv6/IPv2020/g' in the text.
> 
>> It would be much better to say that DHCP as a whole is disabled.
> 
> Sorry, I'm not sure I understand. The draft is proposing that if a
> client is willing to live w/o IPv4 and the server confirms that IPv4
> is optional on the network segment, the client is disabling DHCP for
> some time.
> What would you like us to change?

Just the wording basically.
It assmues only IPv6.
I dislike it when different protocol families discuss each other - IPv6 
should not turn off IPv4, likewise IPv4 should not turn off IPv6.
I would prefer it if Iv6 was not mentioned at all outside of a use case 
for the option.

"The network" should say if each protocol should be used *for* each 
protocol.
I know for sure that there are other network protocols at the equivalent 
OSI layer - sure not as popular as IPv6 but why exclude them as well?

> 
>> 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.
> 
> The draft covers that scenario. DHCPv4 is disabled for V6ONLY_WAIT seconds.

Is the wait seconds even needed?
Just set the T2 timer and treat it as leasing the unspecified address. 
Less data on the wire, less churn in DHCP clients. V6ONLY_WAIT provides 
nothing of value as I see it.

Roy