Re: [dhcwg] [Last-Call] Iotdir last call review of draft-ietf-dhc-v6only-03

Jen Linkova <> Wed, 24 June 2020 23:14 UTC

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From: Jen Linkova <>
Date: Thu, 25 Jun 2020 09:14:13 +1000
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To: Philip Homburg <>
Cc: Lorenzo Colitti <>, "" <>, "" <>, "" <>, "" <>
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Subject: Re: [dhcwg] [Last-Call] Iotdir last call review of draft-ietf-dhc-v6only-03
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On Wed, Jun 24, 2020 at 7:15 PM Philip Homburg
<> wrote:
> Making IPv6 hosts deal with all the brokenness of IPv4, which includes NAT,
> small PMTUs, bad ICMPs, is not progress. And then the way DNS64 breaks with
> local DNSSEC validation is another negative factor.
> Of course, any host can avoid that by running 464xlat. Which just comes at
> the cost of hard to diagnose network problems. Of course this proposal makes
> it even worse by running native IPv4 next to pure NAT64 and 464xlat (and of
> course native IPv6 as well), making it extra hard for any operator to figure
> out what is going on.

I'm not sure how this proposal is different from having two VLANs -
one is dual-stack and one is IPv6-only. The only difference is that
all hosts belong to one IPv6 subnet.
Actually you can say exactly the same about any dual-stack network.
It's hard to troubleshoot because sometimes the device is using IPv4,
sometimes it's using IPv6...
I found it *much* easier to capture/troubleshoot flows in one protocol
than in two.

> This is just something that should not be deployed.

Are you suggesting we move to run IPv4-only hosts and 464xlat on the
first-hop routers?
Unfortunately there are networks where this would not work.

SY, Jen Linkova aka Furry