Re: Confirmation to advance: draft-ietf-6man-ipv6only-flag-05

[Brian E Carpenter <[e-mail]>]

On 11-May-19 01:50, Sander Steffann wrote:
> Hi David,
> 
>> I have to agree that a "hard off" for IPv4, especially global scope unicast IPv4 is not necessary, it is not the problem. If a dual-stack host doesn't get an IPv4 DHCPOFFER, it won't do global scope unicast IPv4. The primary problem described in the problem statement is RFC 3927 and futile IPv4 service discovery using Link-Local IPv4 addresses. I am suggesting we change the flag to be a "hard off" only for RFC 3927, and then its a heuristic hint to fairly quickly stop, or at least severely limit, periodic IPv4 DHCPDISCOVERS, or a "soft off" for global scope unicast IPv4.
>>
>> Furthermore, at least in the near-term, I don't believe IPv6-Only networks are going to be very common. Therefore, I don't think delaying the initial IPv4 DHCPDISCOVERS until the IPv6 RAs can be analyzed is a good tactic.  While I think it should be permitted, I don't think it should be encouraged, at least until IPv6-Only networks become the dominant solution and dual-stack or IPv4-Only networks are rare. Which is by no means the case today. Today, delaying initial IPv4 DHCPDISCOVERS is bad advice.
> 
> That sounds like a good way forward.

I think I agree, except that I don't think the IETF should utter an edict about exactly how hosts do all this, because things will change over time. So whatever we say should be at most a SHOULD, and probably this WG shouldn't get too far into operational recommendations anyway.

    Brian