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

Ted Lemon <mellon@fugue.com> Tue, 10 December 2019 14:38 UTC

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From: Ted Lemon <mellon@fugue.com>
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Date: Tue, 10 Dec 2019 06:38:43 -0800
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Cc: Lorenzo Colitti <lorenzo=40google.com@dmarc.ietf.org>, Tomek Mrugalski <tomasz.mrugalski@gmail.com>, "draft-link-dhc-v6only@ietf.org" <draft-link-dhc-v6only@ietf.org>, V6 Ops List <v6ops@ietf.org>, "dhcwg@ietf.org" <dhcwg@ietf.org>
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To: "STARK, BARBARA H" <bs7652@att.com>
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Archived-At: <https://mailarchive.ietf.org/arch/msg/v6ops/SHXUfEWvAt0ODXfa9VgkAiGWga4>
Subject: Re: [v6ops] [dhcwg] IPv6-Only Preferred DHCPv4 option
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Good point. We’re wrestling with the same thing for ipv6 right now. 

> On Dec 10, 2019, at 06:04, STARK, BARBARA H <bs7652@att.com> wrote:
> 
> 
> On Tue, Dec 10, 2019 at 10:25 AM Tomek Mrugalski <tomasz.mrugalski@gmail.com> wrote:
> That's a good analogy. Would it be helpful if the V6ONLY_WAIT description was update to say something similar to: "Upon reception of the V6ONLY_WAIT option, the client sets its reverts back to DHCPDISCOVER retransmission and sets its retransmission timer to V6ONLY_WAIT seconds"?
>  
> If it sets its retransmission timer to V6ONLY_WAIT seconds, then if the first discover is dropped, will the second one be V6ONLY_WAIT seconds after that? That seems bad. Once the V6ONLY_WAIT timer fires, we want the retransmission interval to be back to a low value, like 1-2 seconds, right?
>  
> Perhaps it's poorly named, but it's very much DHCPv4 option. The option is not supposed to affect any IPv6 behavior.
> 
> How about calling it what it really is: DISABLEV4?
>  
> It's not just "disable IPv4". It's "disable IPv4, because you there's this other thing instead". See https://mailarchive.ietf.org/arch/msg/dhcwg/Xc0yQIXWkKMCLlxhM-Bp0EW0P7w and follow-ups.
>  
> <bhs> Is it really “disable IPv4 ...” or “disable DHCPv4 address acquisition for a while”? I thought hosts were still free to use autoconfigured IPv4 addresses (169.254.x.x) on the LAN. I ask because I don’t want to go down that rat-hole of people thinking it might be ok for routers to start blocking everything on the IPv4 ethertype if this option is sent from the router’s DHCPv4 server. We’re just trying to save on DHCPv4 address assignment with this, aren’t we?
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