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

Michael Richardson <mcr+ietf@sandelman.ca> Thu, 05 December 2019 13:56 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
To: David Farmer <farmer@umn.edu>
cc: Jen Linkova <furry13@gmail.com>, dhcwg@ietf.org, V6 Ops List <v6ops@ietf.org>, draft-link-dhc-v6only@ietf.org
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Date: Thu, 05 Dec 2019 08:56:32 -0500
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Subject: Re: [v6ops] [dhcwg] IPv6-Only Preferred DHCPv4 option
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David Farmer <farmer@umn.edu> wrote:
    Jen> Actually the more I think about it the more I believe the host
    Jen> should be doing whatever they are doing w/o DHCPv4 presence. Android
    Jen> does not configure IPv4 link-locals, MacOS does. Making the same OS
    Jen> behaving differently ("no DHCPv4 whatsoever" vs "DHCPv4 server
    Jen> responded with IPv6-only Preferred option") might be undesirable. As
    Jen> an operator I'd expect that IPv6-only capable host would behave the
    Jen> same way on a dedicated IPv6-only segment and on IPv6-mostly
    Jen> segment.

    > Regarding IPv4-LL, I like Roy Marples suggestion of combining this with RFC
    > 2563 to determine if a host is to configure an IPv4-LL, and in that case, the
    > address returned should be 0.0.0.0.

I agree.
I didn't know that we had 2563 to turn off LL.
So hosts should do whatever they want, and if the operator does not want
v4LL, then they can turn this on.

    > Also, is there any reason that 0.0.0.0 shouldn't be the address retunded by a
    > server "if the IPv6-only Preferred option is present in the Parameter Request
    > List received from the client and the corresponding DHCP pool is explicitly
    > configured as belonging to an IPv6-mostly network segment" as discussed in
    > Section 3.3?

I think that we were concerned that stupid hosts might configure it by
mistake.

--
Michael Richardson <mcr+IETF@sandelman.ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-

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