Subject: [dhcwg] I-D Action: draft-ietf-dhc-v6only-08.txt

From: [email-masked]
Date: Thu, 13 Aug 2020 16:36:51 -0700

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Dynamic Host Configuration WG of the IETF.

        Title           : IPv6-Only-Preferred Option for DHCPv4
        Authors         : Lorenzo Colitti
                          Jen Linkova
                          Michael C. Richardson
                          Tomek Mrugalski
	Filename        : draft-ietf-dhc-v6only-08.txt
	Pages           : 14
	Date            : 2020-08-13

Abstract:
   This document specifies a DHCPv4 option to indicate that a host
   supports an IPv6-only mode and is willing to forgo obtaining an IPv4
   address if the network provides IPv6 connectivity.  It also updates
   RFC2563 to specify the DHCPv4 server behavior when the server
   receives a DHCPDISCOVER not containing the Auto-Configure option but
   containing the new option defined in this document.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-ietf-dhc-v6only/

There are also htmlized versions available at:
https://tools.ietf.org/html/draft-ietf-dhc-v6only-08
https://datatracker.ietf.org/doc/html/draft-ietf-dhc-v6only-08

A diff from the previous version is available at:
https://www.ietf.org/rfcdiff?url2=draft-ietf-dhc-v6only-08

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

---

From: Alexandre Petrescu <[email-masked]>
Date: Mon, 17 Aug 2020 14:40:02 +0200

Hi,

The draft says:
> IPv6-only mode: a mode of operation when a host acts as an IPv6-only 
> capable host and does not have IPv4 addresses assigned (except that 
> IPv4 link-local addresses [RFC3927] may have been configured).

I disagree with this definition, because of the exception it allows, and
because of using only the term Host.

There is no exception in IPv6-only.  There is no IPv4 address in an
IPv6-only computer, be it link-local or loopback.

In an IPv6-only computer the IPv4 stack is removed altogether from the
running space.  It my reside in a file on the disk, but not in RAM and
not swapped either.  Maybe some IPv4 address might still be present in
'hosts' file but that is on disk too, not in memory.

For example, in Windows, uncheck the IPv4 box from interface properties.
  In BSD remove the IPv4 kernel module.  (in linux it's still impossible
to remove it, and from android too; that makes it that one cant get an
IPv6-only linux-based computer, but that's the way it is today).

I propose the following definition:

IPv6-only mode: a mode of operation of a computer whose IPv4 stack has
been removed from the running space and where IPv6 stack is active.

Alex

Le 14/08/2020 à 01:36, [email-masked] a écrit :
> 
> A New Internet-Draft is available from the on-line Internet-Drafts
> directories. This draft is a work item of the Dynamic Host
> Configuration WG of the IETF.
> 
> Title           : IPv6-Only-Preferred Option for DHCPv4 Authors
> : Lorenzo Colitti Jen Linkova Michael C. Richardson Tomek Mrugalski 
> Filename        : draft-ietf-dhc-v6only-08.txt Pages           : 14 
> Date            : 2020-08-13
> 
> Abstract: This document specifies a DHCPv4 option to indicate that a
> host supports an IPv6-only mode and is willing to forgo obtaining an
> IPv4 address if the network provides IPv6 connectivity.  It also
> updates RFC2563 to specify the DHCPv4 server behavior when the
> server receives a DHCPDISCOVER not containing the Auto-Configure
> option but containing the new option defined in this document.
> 
> 
> Please note that it may take a couple of minutes from the time of
> submission until the htmlized version and diff are available at
> tools.ietf.org.
> 
> _______________________________________________ dhcwg mailing list 
> [email-masked] https://www.ietf.org/mailman/listinfo/dhcwg
>

---

From: Lorenzo Colitti <[email-masked]>
Date: Mon, 17 Aug 2020 21:48:07 +0900

> been removed from the running space and where IPv6 stack is active.

The definition you propose will not work for this document for at least the
following two reasons:

   - A host that is IPv6-only by your proposed definition cannot implement
   DHCPv4, because DHCPv4 requires sending and receiving IPv4 packets.
   - In section 3 draft explains that the client can decide that only
   certain interfaces are IPv6-only. This means it could be using IPv4 on
   other interfaces, and it would not meet your proposed definition.

Cheers,
Lorenzo

---

From: Alexandre Petrescu <[email-masked]>
Date: Mon, 17 Aug 2020 17:31:59 +0200

Le 17/08/2020 à 14:48, Lorenzo Colitti a écrit :
> On Mon, Aug 17, 2020 at 9:40 PM Alexandre Petrescu 
> <[email-masked] <mailto:[email-masked]>> 
> wrote:
> 
> IPv6-only mode: a mode of operation of a computer whose IPv4 stack 
> has been removed from the running space and where IPv6 stack is 
> active.
> 
> 
> The definition you propose will not work for this document for at 
> least the following two reasons:
> 
> * A host that is IPv6-only by your proposed definition cannot 
> implement DHCPv4, because DHCPv4 requires sending and receiving IPv4
>  packets.

I agree.

> * In section 3 draft explains that the client can decide that only 
> certain interfaces are IPv6-only. This means it could be using IPv4 
> on other interfaces, and it would not meet your proposed definition.

I agree with this as well.  Turning IPv4 off on some interface might
still leave it on on another interface.  In my tests I make sure the
only interface working has IPv4 disabled and IPv6 enabled.

Still, maybe it's just me.

The definition might promiss the term 'IPv6-only' for something it does
not really satisfy.

If I order a Vanilla-only ice cream I will refuse the slightest trace of
chocolate.

If it is 'IPv6-only' then there is no IPv4 address on any interface, and
the whole IPv4 stack is removed.

What the draft calls 'IPv6-only' is something heading towards true
IPv6-only (more than dual stack) but still not reaching it.  It is
'almost IPv6-only'.

So, maybe the term 'IPv6-only' is not appropriate.  Maybe 'almost
IPv6-only' is better(?)

Alex

> Cheers, Lorenzo

---

From: Alexandre Petrescu <[email-masked]>
Date: Mon, 17 Aug 2020 17:41:55 +0200

Also, I wanted to say.

I think you will disagree with my terminology proposals and that's fine.
  I will not argue any further.

We all work towards progressing towards deployment of IPv6 and this
draft and its potential implementation is a step forward.

I think the problem here is a much wider terminology problem.

Starting simply with 'IPv6', some people understand it as a service,
others as a stack of layers, others as a deployment strategy, others
simply as SLAAC, others as the other version of IP, and so on.  It's
then hard to agree about its '-only' variation.

I have first noticed that divergence in the long argumentations in v6ops
WG about 'IPv6-only' and the billions of devices.

And I dont think I can understand, and even less to speak like others
speak, when I think 'IPv6-only'.

So I will leave it there.

Alex

Le 17/08/2020 à 17:31, Alexandre Petrescu a écrit :
>> <[email-masked]
>> <mailto:[email-masked]>> wrote:
>> 
>> implement DHCPv4, because DHCPv4 requires sending and receiving
>> IPv4 packets.
> 
> I agree.
> 
>>  certain interfaces are IPv6-only. This means it could be using
>> IPv4 on other interfaces, and it would not meet your proposed
>> definition.
> 
> The definition might promiss the term 'IPv6-only' for something it
> does not really satisfy.
> 
> If I order a Vanilla-only ice cream I will refuse the slightest trace
> of chocolate.
> 
> If it is 'IPv6-only' then there is no IPv4 address on any interface,
> and the whole IPv4 stack is removed.
>