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

Lorenzo Colitti <lorenzo@google.com> Fri, 06 December 2019 07:21 UTC

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From: Lorenzo Colitti <lorenzo@google.com>
Date: Fri, 06 Dec 2019 16:21:19 +0900
Message-ID: <CAKD1Yr3OjCsMNM+P2tt9EPrkXDhP+yMptKg-AG3OA1KNbsrqhQ@mail.gmail.com>
To: Jen Linkova <furry13@gmail.com>, Tomek Mrugalski <tomasz.mrugalski@gmail.com>
Cc: David Farmer <farmer@umn.edu>, Michael Richardson <mcr+ietf@sandelman.ca>, dhcwg@ietf.org, V6 Ops List <v6ops@ietf.org>, draft-link-dhc-v6only@ietf.org
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Subject: Re: [v6ops] [dhcwg] IPv6-Only Preferred DHCPv4 option
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On Fri, Dec 6, 2019 at 4:14 PM Jen Linkova <furry13@gmail.com> wrote:

> "If the pool is explicitly configured with a dedicated IPv4
>    address to be returned to IPv6-only capable clients the server MUST
>    specify that address as the client's network address and MUST NOT
>    verify its uniqueness.
>

That seems difficult to implement on the server. Why not just return a
normal OFFER from the pool? That way, if something unexpected happens and
the client sends a DHCPREQUEST for it, the server can hand it out as normal.

The alternative is risky. If the server uses a bogus OFFER value, and some
client requests it and the server hands it out, that creates the
possibility for misconfiguration or bugs to create really bad outcomes
where multiple hosts have the same IP address, or some things on the
network (e.g., snooping switches) think that multiple hosts have the same
IP address. +Tomek Mrugalski <tomasz.mrugalski@gmail.com> any thoughts on
whether this can be implemented easily and reliably on the server side?

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