Re: [v6ops] I-D Action: draft-mawatari-v6ops-464xlat-00.txt

Cameron Byrne <cb.list6@gmail.com> Mon, 30 January 2012 23:06 UTC

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References: <067E6CE33034954AAC05C9EC85E2577C073C54B4@XMB-RCD-111.cisco.com> <20120127103118kawashimam@mail.jp.nec.com> <067E6CE33034954AAC05C9EC85E2577C073C63FC@XMB-RCD-111.cisco.com> <CAD6AjGTi15JA=_3sXqr57Fng_6gqZn2tLmy8nF8AFB+-ZqVQQA@mail.gmail.com> <067E6CE33034954AAC05C9EC85E2577C073C6425@XMB-RCD-111.cisco.com>
Date: Mon, 30 Jan 2012 15:06:04 -0800
Message-ID: <CAD6AjGTVQjDqGCgdJYBzCh9J=4yfikO4WdAHrB9HPCrhtsQ9MQ@mail.gmail.com>
From: Cameron Byrne <cb.list6@gmail.com>
To: "Rajiv Asati (rajiva)" <rajiva@cisco.com>
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Cc: IPv6 Operations <v6ops@ietf.org>
Subject: Re: [v6ops] I-D Action: draft-mawatari-v6ops-464xlat-00.txt
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On Mon, Jan 30, 2012 at 2:59 PM, Rajiv Asati (rajiva) <rajiva@cisco.com> wrote:
> Hi Cameron,
>
>> Just like a common home router today, the CLAT will assign RFC1918
>> space to the home client, but instead of doing NAT44 it will do RFC
>> 6145 protocol translation as described in the draft.
>>
>> Does this answer your question?
>
> Yes, it does. And thanks for going over the basics.
>
> I gather that CLAT has nothing to do with the public IPv4 address, though PLAT absolutely does.
>

Yes, a main goal is to decouple edge network growth from IPv4
availability and scale.

>> The 464XLAT draft is focused on transition to an IPv6-only ISP access
>> network where IPv4 is highly scarce.  So, the explicit assumption is
>> that RFC1918 IPv4 addresses are used behind the CLAT.
>
> Acked.
>
>> > On a basic note, How DNS and HTTP be ever useful for ipv6 prefix
>> > assignment?
>> >
>>
>> I having trouble parsing this last question?  Can you explain some more?
>
> Sure. Section 7.7 mentions DNS and HTTP for IPv6 prefix assignment, and I just don't follow that, thinking about DHCP (or even TR-069) being used for prefix assignment. Why should they be used (and how)?
>

Ah.  I am not sure :)  If it is confusing, it may be best to simplify
that list.  The DNS method might overlap with our explicit mentions of
draft-ietf-behave-nat64-discovery-heuristic

We can simplify this area to avoid confusion.

Thanks again!

Cameron

> Cheers,
> Rajiv
>
>
>> -----Original Message-----
>> From: Cameron Byrne [mailto:cb.list6@gmail.com]
>> Sent: Monday, January 30, 2012 5:50 PM
>> To: Rajiv Asati (rajiva)
>> Cc: Masanobu Kawashima; IPv6 Operations
>> Subject: Re: [v6ops] I-D Action: draft-mawatari-v6ops-464xlat-00.txt
>>
>> Hi Rajiv,
>>
>> On Mon, Jan 30, 2012 at 2:26 PM, Rajiv Asati (rajiva) <rajiva@cisco.com>
>> wrote:
>> > Masanobu-San,
>> >
>> > 1. How could the DHCPv4 be used here for v4 address assignment, since
>> > CLAT enabled device is supposed to have only IPv6? Does it even make
>> > sense to use DHCPv4? Perhaps, specify DHCPv6 (new option, say) usage.
>> >
>>
>> The CLAT may be a home gateway or a cell phone.  Facing the WAN ISP
>> network, the CLAT interface is only IPv6.  Facing the subscriber home
>> network, the CLAT is dual-stack.  For IPv6 flows, the CLAT is a basic
>> IPv6 router.  For IPv4 flows, the CLAT is does stateless RFC 6145
>> translation.
>>
>> In this way, the CLAT is a DHCPv4 server for IPv4 clients in the home
>> network. It may also be a DHCPv6 server for subscriber IPv6 clients
>> and a DHCPv6 client of the ISP network.
>>
>> Just like a common home router today, the CLAT will assign RFC1918
>> space to the home client, but instead of doing NAT44 it will do RFC
>> 6145 protocol translation as described in the draft.
>>
>> Does this answer your question?
>>
>> > I agree with you to adding some explicit language and requirement on
>> > this very point, since IPv4 address assignment is key. Also, it would be
>> > worth clarifying whether CLAT cares about private IPv4 or public IPv4
>> > assignment or both. I presume the last, suffice to say.
>> >
>>
>> The 464XLAT draft is focused on transition to an IPv6-only ISP access
>> network where IPv4 is highly scarce.  So, the explicit assumption is
>> that RFC1918 IPv4 addresses are used behind the CLAT.
>>
>> > 2. Agreed. Having DNS-proxy is reasonable.
>> >
>>
>> ACK
>>
>> > 3. Agreed. Given that the router function (virtual or not) is mandatory
>> > on the CLAT enabled device (gateway or mobile device) for this proposal
>> > to work, I would urge you to mention that explicitly not only in section
>> > 7.4, but also in section 3 where CLAT is defined first.
>> >
>>
>> ACK
>>
>> > 5. Agreed. It would be better to mention DHCP-PD as the recommended
>> > mechanism, while allowing the other mechanism. I would get rid of the
>> > word 'auto' from the title, btw. While we agree to IA_PD, is there a
>> > need for IA_NA? It would be worth clarifying in that section.
>> >
>> > On a basic note, How DNS and HTTP be ever useful for ipv6 prefix
>> > assignment?
>> >
>>
>> I having trouble parsing this last question?  Can you explain some more?
>>
>> Thanks again for the useful review and insightful questions.
>>
>> CB
>>
>> > Cheers,
>> > Rajiv
>> >
>> >> -----Original Message-----
>> >> From: Masanobu Kawashima [mailto:kawashimam@vx.jp.nec.com]
>> >> Sent: Thursday, January 26, 2012 8:31 PM
>> >> To: Rajiv Asati (rajiva)
>> >> Cc: Brian E Carpenter; IPv6 Operations
>> >> Subject: RE: [v6ops] I-D Action: draft-mawatari-v6ops-464xlat-00.txt
>> >>
>> >>
>> >> Dear Rajiv,
>> >>
>> >> Thank you for your comments.
>> >>
>> >> >1. How is IPv4 address getting assigned to the host?
>> >>
>> >> The 464XLAT architecture does not have any requirements on how the
>> > IPv4
>> >> address is assigned. It can be assigned via static or dhcpv4. We
>> > should
>> >> add some language that the subnet must be defined in the CLAT to
>> > better
>> >> define the scope of stateless translation.
>> >>
>> >> The CLAT can acts just like other home gateways or mobile hotspots
>> > that
>> >> assign RFC1918 address (such as 192.168.1.x/24) to clients. There is
>> >> nothing special about the CLAT in how it assigns the address to a
>> > client.
>> >>
>> >>
>> >> >2. Could we not use an existing DHCP option to convey DNS server IPv4
>> >> >address to the CLAT device, which can convey the DNSv4 address the
>> > same
>> >> >way as IPv4 address is conveyed? If we could, then we would not need
>> > DNS
>> >> >proxy function on CLAT.
>> >>
>> >> The focus of this effort is on an IPv6-only access network. We don't
>> > see
>> >> an architectural benefit of doing 464XLAT translation for each DNS
>> > request.
>> >> As stated to Brian, the host may have its own choice of DNS servers,
>> >> including IPv4 DNS servers that require 464XLAT, but that is not the
>> > design
>> >> we would like to promote as the ideal case.
>> >>
>> >>
>> >> >3. Section 7.4 requires CLAT device to have router function. What
>> >> >happens if it is a typical host device (without any router function)?
>> >> >
>> >> >~~~~~~~~~
>> >> >7.4. DNS Proxy Implementation
>> >> >   If a router implement CLAT function, it performs DNS Proxy for
>> > IPv4
>> >> >   hosts and IPv6 hosts in end-user network.  It MUST provide name
>> >> >   resolution with IPv6 transport.  It does not need DNS64 [RFC6147]
>> >> >~~~~~~~~~~~~~~~
>> >>
>> >> The router function can be virtual. This is the case of the Nokia n900
>> > and
>> >> Android, which are really just hosts.
>> >>
>> >>
>> >> >4.  In section 8, did you mean to say IPv4 -> IPv6 -> IPv4
>> > translation
>> >> >below? :-)
>> >> >~~~~~~~~~~~~
>> >> >...
>> >> >   This 464XLAT architecture has two capabilities.  One is a IPv6 ->
>> >> >   IPv4 -> IPv6 translation for sharing global IPv4 addresses,
>> > another
>> >> >~~~~~~~~~
>> >>
>> >> Yes. It is an error in writing. :-)
>> >>
>> >>
>> >> >5. Section 7.7 (Auto IPv6 Prefix Assignment) could benefit from some
>> >> >explicit recommendation (since the current text says source v6 prefix
>> >> >assignment is done via DHCPv6-PD or another method, and destination
>> > IPv6
>> >> >prefix assignment is via some method).
>> >>
>> >> It depends on network operator. Why would more explicit help?
>> >> We would like to keep the options flexible so that solution can evolve
>> >> with different wireline and wireless network capabilities. But, we
>> > agree
>> >> dhcpv6-pd is good today. We just do not want to exclude other options
>> >> without a reason.
>> >>
>> >> Regards,
>> >> Masanobu
>> >>
>> >>
>> >> >Masanobu-san,
>> >> >
>> >> >This is an interesting discussion and proposal. Few Q --
>> >> >
>> >> >1. How is IPv4 address getting assigned to the host?
>> >> >2. Could we not use an existing DHCP option to convey DNS server IPv4
>> >> >address to the CLAT device, which can convey the DNSv4 address the
>> > same
>> >> >way as IPv4 address is conveyed? If we could, then we would not need
>> > DNS
>> >> >proxy function on CLAT.
>> >> >3. Section 7.4 requires CLAT device to have router function. What
>> >> >happens if it is a typical host device (without any router function)?
>> >> >
>> >> >~~~~~~~~~
>> >> >7.4. DNS Proxy Implementation
>> >> >   If a router implement CLAT function, it performs DNS Proxy for
>> > IPv4
>> >> >   hosts and IPv6 hosts in end-user network.  It MUST provide name
>> >> >   resolution with IPv6 transport.  It does not need DNS64 [RFC6147]
>> >> >~~~~~~~~~~~~~~~
>> >> >
>> >> >4.  In section 8, did you mean to say IPv4 -> IPv6 -> IPv4
>> > translation
>> >> >below? :-)
>> >> >~~~~~~~~~~~~
>> >> >...
>> >> >   This 464XLAT architecture has two capabilities.  One is a IPv6 ->
>> >> >   IPv4 -> IPv6 translation for sharing global IPv4 addresses,
>> > another
>> >> >~~~~~~~~~
>> >> >
>> >> >5. Section 7.7 (Auto IPv6 Prefix Assignment) could benefit from some
>> >> >explicit recommendation (since the current text says source v6 prefix
>> >> >assignment is done via DHCPv6-PD or another method, and destination
>> > IPv6
>> >> >prefix assignment is via some method).
>> >> >
>> >> >Cheers,
>> >> >Rajiv
>> >> >
>> >> >
>> >> >> -----Original Message-----
>> >> >> From: v6ops-bounces@ietf.org [mailto:v6ops-bounces@ietf.org] On
>> > Behalf
>> >> >Of
>> >> >> Masanobu Kawashima
>> >> >> Sent: Tuesday, January 24, 2012 12:21 PM
>> >> >> To: Brian E Carpenter
>> >> >> Cc: IPv6 Operations
>> >> >> Subject: Re: [v6ops] I-D Action:
>> > draft-mawatari-v6ops-464xlat-00.txt
>> >> >>
>> >> >>
>> >> >> Hi Brian,
>> >> >>
>> >> >> Thank you for your comment.
>> >> >>
>> >> >> I take your point. However, a CLAT can only learn the address of an
>> >> >IPv6
>> >> >> DNS recursive server through DHCPv6 (or other way). The CLAT can
>> > not
>> >> >easily
>> >> >> discover the address of an IPv4 DNS recursive server, and it has to
>> >> >perform
>> >> >> all DNS resolution over IPv6.
>> >> >>
>> >> >> The CLAT can pass this IPv6 address to downstream IPv6 hosts, but
>> > not
>> >> >to
>> >> >> downstream IPv4 hosts. As such, the CLAT should implement a DNS
>> > proxy.
>> >> >>
>> >> >> Regards,
>> >> >> Masanobu
>> >> >>
>> >> >>
>> >> >> >> 7.4.  DNS Proxy Implementation
>> >> >> >>
>> >> >> >>    If a router implement CLAT function, it performs DNS Proxy
>> > for
>> >> >IPv4
>> >> >> >>    hosts and IPv6 hosts in end-user network.
>> >> >> >
>> >> >> >Why is this necessary? As far as I can see, the client could use
>> > any
>> >> >> >normal DNS server, because the A and AAAA records it needs are
>> >> >completely
>> >> >> >standard.
>> >> >> >
>> >> >> >Regards
>> >> >> >   Brian Carpenter
>> >> >> >
>> >> >> >_______________________________________________
>> >> >> >v6ops mailing list
>> >> >> >v6ops@ietf.org
>> >> >> >https://www.ietf.org/mailman/listinfo/v6ops
>> >> >>
>> >> >> ========================================
>> >> >>  NEC AccessTechnica, Ltd.
>> >> >>  Product Development Department
>> >> >>  Masanobu Kawashima
>> >> >>  kawashimam@vx.jp.nec.com
>> >> >>  http://www.necat.co.jp/
>> >> >> ========================================
>> >> >>
>> >> >> _______________________________________________
>> >> >> v6ops mailing list
>> >> >> v6ops@ietf.org
>> >> >> https://www.ietf.org/mailman/listinfo/v6ops
>> >>
>> >> ========================================
>> >>  NEC AccessTechnica, Ltd.
>> >>  Product Development Department
>> >>  Masanobu Kawashima
>> >>  kawashimam@vx.jp.nec.com
>> >>  http://www.necat.co.jp/
>> >> ========================================
>> >
>> > _______________________________________________
>> > v6ops mailing list
>> > v6ops@ietf.org
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