Re: [v6ops] [dhcwg] Fwd: New Version Notification for draft-link-dhc-v6only-01.txt

David Farmer <farmer@umn.edu> Tue, 10 December 2019 17:24 UTC

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From: David Farmer <farmer@umn.edu>
Date: Tue, 10 Dec 2019 11:24:17 -0600
Message-ID: <CAN-Dau1F794J3GzDKNmSX+hGBauQbJ954-7ViOGZN9XHs1cRWQ@mail.gmail.com>
To: "Bernie Volz (volz)" <volz@cisco.com>
Cc: Ted Lemon <mellon@fugue.com>, "dhcwg@ietf.org" <dhcwg@ietf.org>, V6 Ops List <v6ops@ietf.org>
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Subject: Re: [v6ops] [dhcwg] Fwd: New Version Notification for draft-link-dhc-v6only-01.txt
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Bernie,

Could you provide a couple of pointers to threads where the 0.0.0.0 address
issue was discussed?

I would like to better understand the issues around using 0.0.0.0 as the
address returned, with making you re-debate the issue.

Thanks

On Tue, Dec 10, 2019 at 10:53 AM Bernie Volz (volz) <volz@cisco.com> wrote:

> I've debated that issue on end and not going to do it any further. I
> completely disagree - server should return whatever it would have returned
> if the option is were not present.
>
> - Bernie
>
> -----Original Message-----
> From: Ted Lemon <mellon@fugue.com>
> Sent: Tuesday, December 10, 2019 11:39 AM
> To: Bernie Volz (volz) <volz@cisco.com>
> Cc: mohamed.boucadair@orange.com; Jen Linkova <furry13@gmail.com>;
> dhcwg@ietf.org; V6 Ops List <v6ops@ietf.org>
> Subject: Re: [v6ops] [dhcwg] Fwd: New Version Notification for
> draft-link-dhc-v6only-01.txt
>
> I really think you should have a clear justification for doing anything
> other than returning 0.0.0.0.   Anything else is going to be more
> complicated in the long term.   The justification “because 0.0.0.0 would be
> filtered out by the server” seems like it’s very implementation-dependent
> and not really that big a deal.   Is that your only reason?
>
> > On Dec 10, 2019, at 8:11 AM, Bernie Volz (volz) <volz@cisco.com> wrote:
> >
> > Hi:
> >
> > Is (8):
> >
> >       (8) Consider returning an address from the range defined in
> RFC7335 for IPv6-only hosts. Such IPv4 addresses are required anyway for
> some IPv6-only hosts (those with a CLAT for example).
> >
> >       ====
> >          The result is that 192.0.0.0/29 may be used in any system
> >          that requires IPv4 addresses for backward compatibility with
> IPv4
> >          communications in an IPv6-only network but does not emit IPv4
> packets
> >          "on the wire".
> >       ====
> >
> > But RFC7335 says (in section 4):
> >
> >   IANA has defined a well-known range, 192.0.0.0/29, in [RFC6333],
> >   which is dedicated for DS-Lite.  As defined in [RFC6333], this subnet
> >   is only present between the B4 and the Address Family Transition
> >   Router (AFTR) and never emits packets from this prefix "on the wire".
> <---
> >   464XLAT has the same need for a non-routed IPv4 prefix, and this same
> >   need may be common for other similar solutions.  It is most prudent
> >   and effective to generalize 192.0.0.0/29 for the use of supporting
> >   IPv4 interfaces in IPv6 transition technologies rather than reserving
> >   a prefix for every possible solution.
> >
> > So, this address is only used "on the host" (not on the wire), so why
> would there be any need for the DHCP server to assign this address?
> >
> > And as the IPv6-only option means that the host never completes the
> DHCPDISCOVER/OFFER/REQUEST/ACK (stops at OFFER), this work could not be
> used to assign any address.
> >
> > - Bernie
> >
> > -----Original Message-----
> > From: dhcwg <dhcwg-bounces@ietf.org> On Behalf Of
> > mohamed.boucadair@orange.com
> > Sent: Tuesday, December 10, 2019 5:32 AM
> > To: Jen Linkova <furry13@gmail.com>; dhcwg@ietf.org
> > Cc: V6 Ops List <v6ops@ietf.org>
> > Subject: Re: [dhcwg] Fwd: New Version Notification for
> > draft-link-dhc-v6only-01.txt
> >
> > Hi Jen,
> >
> > Thank you for sharing this updated version. Below some points that I do
> think need more clarification in the I-D:
> >
> > (1) The document is too NAT64 centric. The proposal may apply as well
> for other IPv6-only deployment scenarios (typically, unmanaged IPv6-only
> CPEs with IPv4aaS).
> >
> > (2) A discussion on the benefit of this extra signal compared to relying
> on existing signals (pref64, aftr_name, map_container...). For example, a
> host that supports the option is ready to wait at minimum 300s and disable
> its IPv4 configuration regardless of what is happening on the IPv6 leg. How
> is that superior to a host delaying DHCP process by xxx ms should be
> explained further.
> >
> > (3) How "IPv6-only preferred" mode is supposed to be set at the host
> side:
> >
> > ==
> >   A DHCP client SHOULD allow a device administrator to configure
> >   IPv6-only preferred mode either for a specific interface (to indicate
> >   that the device is IPv6-only capable if connected to a NAT64 network
> >   via that interface) or for all interfaces.
> > ==
> >
> > * I guess the default value when the option is supported by a host is to
> disable including it in the request. The document should include a
> discussion on the default behavior.
> > * If an explicit action is needed from the user to enable including the
> option, having a discussion to what extent the feature is likely to be
> enabled would be needed.
> >
> > (4) The document is still mixing the DHCP client vs. host behaviors.
> > For example,
> >
> >   Clients not capable of operating in an IPv6-only NAT64 environment
> >   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >   MUST NOT include the IPv6-only Preferred option in the Parameter
> >   Request List of any DHCP packets and MUST ignore that option in
> >   packets received from DHCP servers.
> >
> > does not make sense for a DHCP client.
> >
> > Also, how the host is able to assess/determine that it is (not) capable
> to behave in the IPv6 mode?
> >
> > (5) The definition of IPv4aaS is not aligned with other RFCs: e.g.,
> RFC8585 says the following:
> >
> >   "IPv4aaS" stands for "IPv4-as-a-Service", meaning transition
> >   technologies for delivering IPv4 in IPv6-only connectivity.
> >
> > While yours is:
> >
> >   IPv4-as-a-Service: a deployment scenario when end hosts are expected
> >   to operate in IPv6-only mode by default and IPv4 addresses can be
> >   assigned to some hosts if those hosts explicitly opt-in to receiving
> >   IPv4 addresses.
> >
> > (6) Do you consider a host with CLAT function as an IPv6-only host?
> >
> > If so, the following definition should be updated to refer to "IPv4
> connectivity" rather than "IPv4" in general. This is because an IPv4
> address is required for CLAT for example.
> >
> > ==
> >   IPv6-only capable host: a host which does not require IPv4 and can
> >   operate on IPv6-only networks.
> > ==
> >
> > (7) Wouldn't the following add an extra delay for applications requiring
> CLAT?
> >
> > ==
> > The host MAY disable IPv4 stack
> >   completely for V6ONLY_WAIT seconds or until the network disconnection
> >   event happens.
> > ==
> >
> > (8) Consider returning an address from the range defined in RFC7335 for
> IPv6-only hosts. Such IPv4 addresses are required anyway for some IPv6-only
> hosts (those with a CLAT for example).
> >
> > ====
> >   The result is that 192.0.0.0/29 may be used in any system
> >   that requires IPv4 addresses for backward compatibility with IPv4
> >   communications in an IPv6-only network but does not emit IPv4 packets
> >   "on the wire".
> > ====
> >
> > Cheers,
> > Med
> >
> >> -----Message d'origine-----
> >> De : dhcwg [mailto:dhcwg-bounces@ietf.org] De la part de Jen Linkova
> >> Envoyé : mardi 10 décembre 2019 01:02 À : dhcwg@ietf.org Cc : V6 Ops
> >> List Objet : [dhcwg] Fwd: New Version Notification for
> >> draft-link-dhc-v6only- 01.txt
> >>
> >> Hello,
> >>
> >> Thanks to everyone for very productive centi-thread on
> >> draft-link-dhc-v6only-00 ;)
> >> Here is the improved version, -01.
> >>
> >> The main changes:
> >>
> >> - The option is not zero length anymore. It has 4-bytes value which
> >> might contain V6ONLY_WAIT timer. Benefits:
> >>    --- allows the network administrators to pilot the changes and
> >> rollback quickly if needed;
> >>    --- addressed some concern about an option having zero length
> >> (allegedly it might confuse some clients)
> >>
> >> - Using a dedicated address to return to clients is now an optional
> >> optimisation. By default the server is expected just to return a
> >> random address (as usual).
> >>
> >> - Typos fixed (probably some new typos added though).
> >>
> >> The authors would like the DHC WG to consider adopting this document.
> >>
> >> Thank you!
> >>
> >> ---------- Forwarded message ---------
> >> From: <internet-drafts@ietf.org>
> >> Date: Tue, Dec 10, 2019 at 10:44 AM
> >> Subject: New Version Notification for draft-link-dhc-v6only-01.txt
> >> To: Tomek Mrugalski <tomasz.mrugalski@gmail.com>, Lorenzo Colitti
> >> <lorenzo@google.com>, Jen Linkova <furry@google.com>, Michael C.
> >> Richardson <mcr+ietf@sandelman.ca>
> >>
> >>
> >>
> >> A new version of I-D, draft-link-dhc-v6only-01.txt has been
> >> successfully submitted by Jen Linkova and posted to the IETF
> >> repository.
> >>
> >> Name:           draft-link-dhc-v6only
> >> Revision:       01
> >> Title:          IPv6-Only-Preferred Option for DHCP
> >> Document date:  2019-12-09
> >> Group:          Individual Submission
> >> Pages:          10
> >> URL:
> >> https://www.ietf.org/internet-drafts/draft-link-dhc-v6only-01.txt
> >> Status:         https://datatracker.ietf.org/doc/draft-link-dhc-v6only/
> >> Htmlized:       https://tools.ietf.org/html/draft-link-dhc-v6only-01
> >> Htmlized:
> https://datatracker.ietf.org/doc/html/draft-link-dhc-v6only
> >> Diff:
> https://www.ietf.org/rfcdiff?url2=draft-link-dhc-v6only-01
> >>
> >> Abstract:
> >>   This document specifies a DHCP option to indicate that a host
> >>   supports an IPv6-only mode and willing to forgo obtaining an IPv4
> >>   address if the network provides IPv6 connectivity.
> >>
> >>
> >>
> >>
> >> 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.
> >>
> >> The IETF Secretariat
> >>
> >>
> >> --
> >> SY, Jen Linkova aka Furry
> >>
> >> _______________________________________________
> >> dhcwg mailing list
> >> dhcwg@ietf.org
> >> https://www.ietf.org/mailman/listinfo/dhcwg
> >
> > _______________________________________________
> > dhcwg mailing list
> > dhcwg@ietf.org
> > https://www.ietf.org/mailman/listinfo/dhcwg
> >
> > _______________________________________________
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>
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