draft-ietf-v6ops-464xlat-03.txt		draft-ietf-v6ops-464xlat-04.txt
	Internet Engineering Task Force M. Mawatari		Internet Engineering Task Force M. Mawatari
	Internet-Draft Japan Internet Exchange Co.,Ltd.		Internet-Draft Japan Internet Exchange Co.,Ltd.
	Intended status: BCP M. Kawashima		Intended status: BCP M. Kawashima
	Expires: November 9, 2012 NEC AccessTechnica, Ltd.		Expires: December 27, 2012 NEC AccessTechnica, Ltd.
	C. Byrne		C. Byrne
	T-Mobile USA		T-Mobile USA
	May 8, 2012		June 25, 2012
	464XLAT: Combination of Stateful and Stateless Translation		464XLAT: Combination of Stateful and Stateless Translation
	draft-ietf-v6ops-464xlat-03		draft-ietf-v6ops-464xlat-04
	Abstract		Abstract
	This document describes an architecture (464XLAT) for providing		This document describes an architecture (464XLAT) for providing
	limited IPv4 connectivity across an IPv6-only network by combining		limited IPv4 connectivity across an IPv6-only network by combining
	existing and well-known stateful protocol translation RFC 6146 in the		existing and well-known stateful protocol translation RFC 6146 in the
	core and stateless protocol translation RFC 6145 at the edge. 464XLAT		core and stateless protocol translation RFC 6145 at the edge. 464XLAT
	is a simple and scalable technique to quickly deploy limited IPv4		is a simple and scalable technique to quickly deploy limited IPv4
	access service to mobile and wireline IPv6-only edge networks without		access service to IPv6-only edge networks without encapsulation.
	encapsulation.
	Status of this Memo		Status of this Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on November 9, 2012.		This Internet-Draft will expire on December 27, 2012.
	Copyright Notice		Copyright Notice
	Copyright (c) 2012 IETF Trust and the persons identified as the		Copyright (c) 2012 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3		2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
	3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4		3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
	4. Motivation and Uniqueness of 464XLAT . . . . . . . . . . . . . 4		4. Motivation and Uniqueness of 464XLAT . . . . . . . . . . . . . 4
	5. Network Architecture . . . . . . . . . . . . . . . . . . . . . 5		5. Network Architecture . . . . . . . . . . . . . . . . . . . . . 4
	5.1. Wireline Network Architecture . . . . . . . . . . . . . . 6		5.1. Wireline Network Architecture . . . . . . . . . . . . . . 4
	5.2. Wireless 3GPP Network Architecture . . . . . . . . . . . . 7		5.2. Wireless 3GPP Network Architecture . . . . . . . . . . . . 5
	6. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 7		6. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 6
	6.1. Wireline Network Applicability . . . . . . . . . . . . . . 7		6.1. Wireline Network Applicability . . . . . . . . . . . . . . 6
	6.2. Wireless 3GPP Network Applicability . . . . . . . . . . . 8		6.2. Wireless 3GPP Network Applicability . . . . . . . . . . . 7
	7. Implementation Considerations . . . . . . . . . . . . . . . . 9		7. Implementation Considerations . . . . . . . . . . . . . . . . 7
	7.1. IPv6 Address Format . . . . . . . . . . . . . . . . . . . 9		7.1. IPv6 Address Format . . . . . . . . . . . . . . . . . . . 7
	7.2. IPv4/IPv6 Address Translation Chart . . . . . . . . . . . 9		7.2. IPv4/IPv6 Address Translation Chart . . . . . . . . . . . 7
	7.3. Traffic Treatment Scenarios . . . . . . . . . . . . . . . 10		7.2.1. Case of enabling only stateless XLATE on CLAT . . . . 7
	7.4. DNS Proxy Implementation . . . . . . . . . . . . . . . . . 11		7.2.2. Case of enabling NAT44 and stateless XLATE on CLAT . . 9
	7.5. IPv6 Prefix Handling . . . . . . . . . . . . . . . . . . . 11		7.3. IPv6 Prefix Handling . . . . . . . . . . . . . . . . . . . 11
	7.6. Relationship between CLAT and NAT44 . . . . . . . . . . . 11		7.3.1. Case of enabling only stateless XLATE on CLAT . . . . 11
	7.7. CLAT in a Gateway . . . . . . . . . . . . . . . . . . . . 11		7.3.2. Case of enabling NAT44 and stateless XLATE on CLAT . . 11
	7.8. CLAT to CLAT communications . . . . . . . . . . . . . . . 12		7.4. Traffic Treatment Scenarios . . . . . . . . . . . . . . . 12
	8. Deployment Considerations . . . . . . . . . . . . . . . . . . 12		7.5. DNS Proxy Implementation . . . . . . . . . . . . . . . . . 12
	9. Security Considerations . . . . . . . . . . . . . . . . . . . 12		7.6. CLAT in a Gateway . . . . . . . . . . . . . . . . . . . . 12
			7.7. CLAT to CLAT communications . . . . . . . . . . . . . . . 12
			8. Deployment Considerations . . . . . . . . . . . . . . . . . . 13
			9. Security Considerations . . . . . . . . . . . . . . . . . . . 13
	10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13		10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
	11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 13		11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
	12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13		12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
	12.1. Normative References . . . . . . . . . . . . . . . . . . . 13		12.1. Normative References . . . . . . . . . . . . . . . . . . . 14
	12.2. Informative References . . . . . . . . . . . . . . . . . . 13		12.2. Informative References . . . . . . . . . . . . . . . . . . 14
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14		Appendix A. Examples of IPv4/IPv6 Address Translation . . . . . . 15
			Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
	1. Introduction		1. Introduction
	The IANA unallocated IPv4 address pool was exhausted on February 3,		The IANA unallocated IPv4 address pool was exhausted on February 3,
	2011. Each RIR's unallocated IPv4 address pool will exhaust in the		2011. Each RIR's unallocated IPv4 address pool will exhaust in the
	near future. It will be difficult for many networks to assign IPv4		near future. It will be difficult for many networks to assign IPv4
	addresses to end users, despite substantial IP connectivity growth		addresses to end users, despite substantial IP connectivity growth
	required for mobile devices, smart-grid, and cloud nodes.		required for fast growing edge networks.
	This document describes an IPv4 over IPv6 solution as one of the		This document describes an IPv4 over IPv6 solution as one of the
	techniques for IPv4 service extension and encouragement of IPv6		techniques for IPv4 service extension and encouragement of IPv6
	deployment. 464XLAT is not a one for one replacement of full IPv4		deployment. 464XLAT is not a one for one replacement of full IPv4
	functionality. The 464XLAT IPv4 service is limited to application		functionality. The 464XLAT architecture only supports IPv4 in the
	that function in a client server model and is not fit for IPv4 peer-		client server model, where the server has global IPv4 address. This
	to-peer communication or inbound IPv4 connections.		means it is not fit for IPv4 peer-to-peer communication or inbound
			IPv4 connections. 464XLAT builds on IPv6 transport and includes full
			any to any IPv6 communication.
	The 464XLAT architecture described in this document uses IPv4/IPv6		The 464XLAT architecture described in this document uses IPv4/IPv6
	translation standardized in [RFC6145] and [RFC6146]. It does not		translation standardized in [RFC6145] and [RFC6146]. It does not
	require DNS64 [RFC6147] since a host may simply send IPv4 packets,		require DNS64 [RFC6147] since an IPv4 host may simply send IPv4
	including packets to an IPv4 DNS server, which will be translated on		packets, including packets to an IPv4 DNS server, which will be
	the CLAT to IPv6 and back to IPv4 on the PLAT. 464XLAT networks may		translated on the CLAT to IPv6 and back to IPv4 on the PLAT. 464XLAT
	use DNS64 to enable single stateful translation [RFC6146] instead of		networks may use DNS64 [RFC6147] to enable single stateful
	464XLAT double translation where possible. It is also possible to		translation [RFC6146] instead of 464XLAT double translation where
	provide single IPv4/IPv6 translation service, which will be needed in		possible. The 464XLAT architecture encourages IPv6 transition by
	the future case of IPv6-only servers and peers to be reached from		making IPv4 services reachable across IPv6-only networks and
	legacy IPv4-only hosts. The 464XLAT architecture encourages IPv6		providing IPv6 and IPv4 connectivity to single-stack IPv4 or IPv6
	transition by making IPv4 services reachable across IPv6-only		servers and peers.
	networks and providing IPv6 and IPv4 connectivity to single-stack
	IPv4 or IPv6 servers and peers.
	Running a single-stack IPv6-only network has several operational		By combining 464XLAT with BIH [RFC6535], it is also possible to
	benefits in terms of increasing scalability and decreasing		provide single IPv4 to IPv6 translation service, which will be needed
	operational complexity. Unfortunately, there are important cases		in the future case of IPv6-only servers and peers to be reached from
	where IPv6-only networks fail to meet subscriber expectations, as		legacy IPv4-only hosts across IPv6-only networks.
	described in [RFC6586]. The 464XLAT overcomes the issues described
	in [RFC6586] to provide subscribers the full IPv6 and limited IPv4
	functionality while providing the network operator the benefits of a
	simple yet highly scalable single-stack IPv6 network.
	2. Requirements Language		2. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in [RFC2119].		document are to be interpreted as described in [RFC2119].
	3. Terminology		3. Terminology
	PLAT: PLAT is Provider side translator(XLAT) that complies with		PLAT: PLAT is Provider side translator(XLAT) that complies with
	[RFC6146]. It translates N:1 global IPv6 packets to global		[RFC6146]. It translates N:1 global IPv6 packets to global
	IPv4 packets, and vice versa.		IPv4 packets, and vice versa.
	CLAT: CLAT is Customer side translator(XLAT) that complies with		CLAT: CLAT is Customer side translator(XLAT) that complies with
	[RFC6145]. It algorithmically translates 1:1 private IPv4		[RFC6145]. It algorithmically translates 1:1 private IPv4
	packets to global IPv6 packets, and vice versa. The CLAT		packets to global IPv6 packets, and vice versa. The CLAT
	function is applicable to a router or an end-node such as a		function is applicable to a router or an end-node such as a
	mobile phone. CLAT SHOULD perform router function to		mobile phone. CLAT SHOULD perform router function to
	facilitate packets forwarding through the stateless		facilitate packets forwarding through the stateless
	skipping to change at page 4, line 17		skipping to change at page 4, line 14
	PLAT: PLAT is Provider side translator(XLAT) that complies with		PLAT: PLAT is Provider side translator(XLAT) that complies with
	[RFC6146]. It translates N:1 global IPv6 packets to global		[RFC6146]. It translates N:1 global IPv6 packets to global
	IPv4 packets, and vice versa.		IPv4 packets, and vice versa.
	CLAT: CLAT is Customer side translator(XLAT) that complies with		CLAT: CLAT is Customer side translator(XLAT) that complies with
	[RFC6145]. It algorithmically translates 1:1 private IPv4		[RFC6145]. It algorithmically translates 1:1 private IPv4
	packets to global IPv6 packets, and vice versa. The CLAT		packets to global IPv6 packets, and vice versa. The CLAT
	function is applicable to a router or an end-node such as a		function is applicable to a router or an end-node such as a
	mobile phone. CLAT SHOULD perform router function to		mobile phone. CLAT SHOULD perform router function to
	facilitate packets forwarding through the stateless		facilitate packets forwarding through the stateless
	translation even if it is an end-node. In addition to		translation even if it is an end-node. In the case where the
	stateless translation, the CLAT as a common home router or 3G		access network does not allow for a dedicated IPv6 prefix for
	router is expected to perform gateway functions such as DHCP		translation, a NAT44 SHOULD be used between the router
	server and DNS proxy for local clients.		function and the stateless translator function. The CLAT as
			a common home router or 3G router is expected to perform
	UE: The 3GPP term for user equipment. The most common type of UE		gateway functions such as DHCP server and DNS proxy for local
	is a mobile phone.		clients. The CLAT does not comply with the sentence "Both
			IPv4-translatable IPv6 addresses and IPv4-converted IPv6
	PDP: A Packet Data Protocol (PDP) Context is the equivalent of a		addresses SHOULD use the same prefix." that is described on
	virtual connection between the host and a gateway.		Section 3.3 in [RFC6052] due to using different IPv6 prefixes
			for CLAT-side and PLAT-side IPv4 addresses.
	4. Motivation and Uniqueness of 464XLAT		4. Motivation and Uniqueness of 464XLAT
	1. Minimal IPv4 resource requirements, maximum IPv4 efficiency		1. Minimal IPv4 resource requirements, maximum IPv4 efficiency
			through statistical multiplexing
	464XLAT has low barriers to entry since only a small amount of
	IPv4 addresses are needed to support the stateful translation
	[RFC6146] function in the PLAT. With port-overloading, one IPv4
	address can support millions of simultaneous translations.
	Given that network operators are deploying IPv6-only access
	networks because IPv4 resources are scarce, solutions that
	require dual-stack (no IPv4 multiplexing) or stateless address
	sharing (bounded static address multiplexing) are simply not
	IPv4-efficient enough to solve the two-pronged challenge of
	increasing IPv4 address scarcity and continued exponential
	network edge growth for network operators.
	2. No new protocols required, quick deployment		2. No new protocols required, quick deployment
	464XLAT can be deployed today, it uses existing RFCs ([RFC6145]		3. IPv6-only networks are simpler and therefore less expensive to
	and [RFC6146]), and there exists implementations for both		operate
	wireline networks (CLAT in the home router) and wireless 3GPP
	networks (CLAT in the UE). The ability to quickly deploy 464XLAT
	is a critical feature given the urgency of IPv4 exhaustion and
	brisk pace of internet growth.
	3. Cost-effective transition to IPv6
	When combined with DNS64 [RFC6147], the 464XLAT architecture only
	requires double translation in the case of IPv4-referrals or
	IPv4-only socket calls. Consequently, the network traffic in the
	ISP backbone network is predominately IPv6 end-to-end or single
	translation. This is especially cost-effective in wireless 3GPP
	GSM and UMTS networks that would otherwise require two separate
	PDP connections to support IPv4 and IPv6.
	While translation on the CLAT is not always used, the CLAT
	function is crucial for enabling the IPv4-only applications. All
	IPv6-native flows pass end-to-end without any translation. This
	is a beneficial solution for end-users, content providers, and
	network operators that scale best with end-to-end IPv6
	communication.
	In summary, the 464XLAT architecture works today for service
	providers that require large-scale strategic IPv6 deployments to
	overcome the challenges of IPv4 address scarcity. Since 464XLAT is
	stateful, there is no tight coupling or IPv4 address coordination
	between the PLAT and the CLAT. Unlike other transition architectures
	associated with tunneling or
	[I-D.mdt-softwire-mapping-address-and-port], 464XLAT assumes that
	IPv4 is scarce and IPv6 must work with today's existing systems as
	much as possible. In the case of tunneling, the tunneling solutions
	like Dual-Stack Lite [RFC6333] are known to break existing network
	based deep packet inspection solutions like 3GPP standardized Policy
	and Charging Control (PCC). 464XLAT does not require much IPv4
	address space to enable the stateful translation [RFC6146] function
	in the PLAT while providing global IPv4 and IPv6 reachability to
	IPv6-only wireline and wireless subscribers.
	5. Network Architecture		5. Network Architecture
	464XLAT architecture is shown in the following figure.		464XLAT architecture is shown in the following figure.
	5.1. Wireline Network Architecture		5.1. Wireline Network Architecture
			The private IPv4 host on this diagram can reach global IPv4 hosts via
			translation on both CLAT and PLAT. On the other hand, the IPv6 host
			can reach other IPv6 hosts on the Internet directly without
			translation. This means that the CPE can not only have the function
			of CLAT but also the function of IPv6 native router for IPv6 native
			traffic.
	----		----
	| v6 |		| v6 |
	----		----
	|		|
	---- | .---+---. .------.		---- | .---+---. .------.
	| v6 |-----+ / \ / \		| v6 |-----+ / \ / \
	---- | ------ / IPv6 \ ------ / IPv4 \		---- | ------ / IPv6 \ ------ / IPv4 \
	+---| CLAT |---+ Internet +---| PLAT |---+ Internet |		+---| CLAT |---+ Internet +---| PLAT |---+ Internet |
	------- | ------ \ / ------ \ /		------- | ------ \ / ------ \ /
	|v4p/v6 |--+ `---------' `----+----'		|v4p/v6 |--+ `---------' `----+----'
	skipping to change at page 7, line 7		skipping to change at page 5, line 30
	<- v4p -> XLAT <--------- v6 --------> XLAT <- v4g ->		<- v4p -> XLAT <--------- v6 --------> XLAT <- v4g ->
	v6 : Global IPv6		v6 : Global IPv6
	v4p : Private IPv4		v4p : Private IPv4
	v4g : Global IPv4		v4g : Global IPv4
	Figure 1: Wireline Network Topology		Figure 1: Wireline Network Topology
	5.2. Wireless 3GPP Network Architecture		5.2. Wireless 3GPP Network Architecture
			The CLAT function on the UE provides an [RFC1918] address and IPv4
			default route. The applications on the UE can use the private IPv4
			address for reaching global IPv4 hosts via translation on both CLAT
			and PLAT. On the other hand, reaching IPv6 hosts (including host
			presented via DNS64 [RFC6147]) does not require the CLAT function on
			the UE.
	----		----
	| v6 |		| v6 |
	----		----
	|		|
	.---+---.		.---+---.
	/ \		/ \
	/ IPv6 \		/ IPv6 \
	| Internet |		| Internet |
	\ /		\ /
	UE / Mobile Phone `---------'		UE / Mobile Phone `---------'
	+----------------------+ |		+----------------------+ |
	| ---- | | .---+---. .------.		| ---- | | .---+---. .------.
	| | v6 |----+ | / \ / \		| | v6 |----+ | / \ / \
	| ---- | ------| / IPv6 PDP \ ------ / IPv4 \		| ---- | ------| / IPv6 PDP \ ------ / IPv4 \
	| +---| CLAT |---+ Mobile Core +---| PLAT |--+ Internet |		| +---| CLAT |---+ Mobile Core +---| PLAT |--+ Internet |
	| | ------| \ GGSN / ------ \ /		| | ------| \ GGSN / ------ \ /
	| | | \ ' `----+---'		| | | \ ' `----+---'
	| ------ | | `-------' |		| ------ | | `-------' |
	| | v4p |---+ | -----		| | v4p |---+ | -----
	| ------ | | | v4g |		| ------ | | | v4g |
	skipping to change at page 7, line 41		skipping to change at page 6, line 39
	v6 : Global IPv6		v6 : Global IPv6
	v4p : Private IPv4		v4p : Private IPv4
	v4g : Global IPv4		v4g : Global IPv4
	Figure 2: Wireless 3GPP Network Topology		Figure 2: Wireless 3GPP Network Topology
	6. Applicability		6. Applicability
	6.1. Wireline Network Applicability		6.1. Wireline Network Applicability
	When an ISP has IPv6 access network infrastructure and 464XLAT, the		When an ISP has IPv6 464XLAT, the ISP can provide outgoing IPv4
	ISP can provide IPv4 service to end users across an IPv6 access		service to end users across an IPv6 access network. The result is
	network. The result is that edge network growth is no longer tightly		that edge network growth is no longer tightly coupled to the
	coupled to the availability of scarce IPv4 addresses.		availability of scarce IPv4 addresses.
	If the IXP or another provider operates the PLAT, the ISP is only		If the IXP or another provider operates the PLAT, the edge ISP is
	required to deploy an IPv6 access network. All ISPs do not need IPv4		only required to deploy an IPv6 access network. All ISPs do not need
	access networks. They can migrate their access network to a simple		IPv4 access networks. They can migrate their access network to a
	and highly scalable IPv6-only environment. Incidentally, Japan		simple and highly scalable IPv6-only environment.
	Internet Exchange(JPIX) is providing 464XLAT trial service since July
	2010. In addition to this, the effectiveness of 464XLAT was
	confirmed in the WIDE camp Spring 2012. The result is described in
	[I-D.hazeyama-widecamp-ipv6-only-experience].
	6.2. Wireless 3GPP Network Applicability		Incidentally, the effectiveness of 464XLAT was confirmed in the WIDE
			camp Spring 2012. The result is described in
	The vast majority of mobile wireless networks are compliant to Pre-		[I-D.hazeyama-widecamp-ipv6-only-experience].
	Release 9 3GPP standards. In Pre-Release 9 3GPP networks, GSM and
	UMTS networks must signal and support both IPv4 and IPv6 PDP
	attachments to access IPv4 and IPv6 network destinations. Since
	there are 2 PDPs required to support 2 address families, this is
	double the number of PDPs required to support the status quo of 1
	address family, which is IPv4. Doubling the PDP count to support
	IPv4 and IPv6 is generally not operationally viable since a large
	portion of the network cost is derived from the number of PDP
	attachments, both in terms of licenses from the network hardware
	vendors and in terms of actual hardware resources required to support
	and maintain the PDP signaling and mobility events. Doubling the
	number of PDP attachments has been one of the major barriers to
	introducing IPv6 in mobile networks. Dual-stack IPv4 and IPv6 simply
	costs more from the network provider perspective and does not result
	in any new revenues. In 3GPP Release 9 and forward, 2 PDPs are no
	longer required but the scarcity of IPv4 addresses remain.
	Now that both global and private IPv4 addresses are scarce to the		6.2. Wireless 3GPP Network Applicability
	extent that it is a substantial business risk and limiting growth in
	many areas, the mobile network providers must support IPv6 to solve
	the IP address scarcity issue. It is not feasible to simply turn on
	additional IPv6 PDP network attachments since that does not solve the
	near-term IPv4 scarcity issues and it increases cost in most cases.
	The most logical path forward is to replace IPv4 with IPv6 and
	replace the common NAT44 with stateful translation [RFC6146] and
	DNS64 [RFC6147]. Extensive live network testing with hundreds of
	friendly-users has shown that IPv6-only network attachments for
	mobile devices supports over 85% of the common applications on the
	Android mobile operating systems. The remaining 15% of applications
	do not work because the application requires an IPv4 socket or the
	application does an IPv4-referral. These findings are consistent
	with the mobile IPv6-only user experience in [RFC6586].
	464XLAT in combination with stateful translation [RFC6146] and DNS64		464XLAT in combination with stateful translation [RFC6146] and DNS64
	[RFC6147] allows 85% of the Android applications to continue to work		[RFC6147] allows 85% of the Android applications to continue to work
	with single translation or native IPv6 access. For the remaining 15%		with single translation or native IPv6 access. For the remaining 15%
	of applications that require IPv4 connectivity, the CLAT function on		of applications that require IPv4 connectivity, the CLAT function on
	the UE provides a private IPv4 address and IPv4 default-route on the		the UE provides a private IPv4 address and IPv4 default-route on the
	host for the applications to reference and bind to. Connections		host for the applications to reference and bind to. Connections
	sourced from the IPv4 interface are immediately routed to the CLAT		sourced from the IPv4 interface are immediately routed to the CLAT
	function and passed to the IPv6-only mobile network, destine to the		function and passed to the IPv6-only mobile network, destine to the
	PLAT. In summary, the UE has the CLAT function that does a stateless		PLAT. In summary, the UE has the CLAT function that does a stateless
	skipping to change at page 9, line 18		skipping to change at page 7, line 30
	7. Implementation Considerations		7. Implementation Considerations
	7.1. IPv6 Address Format		7.1. IPv6 Address Format
	IPv6 address format in 464XLAT is defined in Section 2.2 of		IPv6 address format in 464XLAT is defined in Section 2.2 of
	[RFC6052].		[RFC6052].
	7.2. IPv4/IPv6 Address Translation Chart		7.2. IPv4/IPv6 Address Translation Chart
	IPv4/IPv6 address translation chart is shown in the following figure.		7.2.1. Case of enabling only stateless XLATE on CLAT
			This case should be used when a prefix delegation mechanism such as
			DHCPv6-PD [RFC3633] is available to assign a dedicated translation
			prefix to the CLAT.
	Source IPv4 address		Source IPv4 address
	+----------------------------+		+----------------------------+
	| Global IPv4 address |		| Global IPv4 address |
	| assigned to IPv4 pool@PLAT |		| assigned to IPv4 pool@PLAT |
	+--------+ +----------------------------+		+--------+ +----------------------------+
	| IPv4 | Destination IPv4 address		| IPv4 | Destination IPv4 address
	| server | +----------------------------+		| server | +----------------------------+
	+--------+ | Global IPv4 address |		+--------+ | Global IPv4 address |
	^ | assigned to IPv4 server |		^ | assigned to IPv4 server |
	skipping to change at page 9, line 48		skipping to change at page 8, line 33
	| defined in Section 2.2 of RFC6052 |		| defined in Section 2.2 of RFC6052 |
	+--------------------------------------------------------------+		+--------------------------------------------------------------+
	Destination IPv6 address		Destination IPv6 address
	+--------------------------------------------------------------+		+--------------------------------------------------------------+
	| IPv4-Embedded IPv6 address |		| IPv4-Embedded IPv6 address |
	| defined in Section 2.2 of RFC6052 |		| defined in Section 2.2 of RFC6052 |
	+--------------------------------------------------------------+		+--------------------------------------------------------------+
	(IPv6 cloud)		(IPv6 cloud)
	^		^
	|		|
			+--------+
			| | In the case CLAT has a
			| | dedicated IPv6 prefix for
			| CLAT | translation, the CLAT behaves
			| | with only Stateless XLATE
			| | (IPv4:IPv6=1:1).
			+--------+
			^ Source IPv4 address
			| +----------------------------+
			+--------+ | Private IPv4 address |
			| IPv4 | | assigned to IPv4 client |
			| client | +----------------------------+
			+--------+ Destination IPv4 address
			+----------------------------+
			| Global IPv4 address |
			| assigned to IPv4 server |
			+----------------------------+
			Case of enabling only stateless XLATE on CLAT
			7.2.2. Case of enabling NAT44 and stateless XLATE on CLAT
			This case should be used when a prefix delegation mechanism is not
			available to assign a dedicated translation prefix to the CLAT. In
			this case, NAT44 SHOULD be used so that all IPv4 source addresses are
			mapped to a single IPv6 address.
			Source IPv4 address
			+----------------------------+
			| Global IPv4 address |
			| assigned to IPv4 pool@PLAT |
			+--------+ +----------------------------+
			| IPv4 | Destination IPv4 address
			| server | +----------------------------+
			+--------+ | Global IPv4 address |
			^ | assigned to IPv4 server |
			| +----------------------------+
			+--------+
			| PLAT | Stateful XLATE(IPv4:IPv6=1:n)
			+--------+
			^
	|		|
			Source IPv6 address (IPv6 cloud)
			+--------------------------------------------------------------+
			| IPv4-Embedded IPv6 address |
			| defined in Section 2.2 of RFC6052 |
			+--------------------------------------------------------------+
			Destination IPv6 address
			+--------------------------------------------------------------+
			| IPv4-Embedded IPv6 address |
			| defined in Section 2.2 of RFC6052 |
			+--------------------------------------------------------------+
			(IPv6 cloud)
			^
	|		|
	+--------+		+--------+
	| | Case 1: CLAT will have a		| | In the case CLAT does not have
	| | dedicated IPv6 prefix		| | a dedicated IPv6 prefix for
	| | -> Stateless XLATE		| CLAT | translation, the CLAT behaves
	| | (IPv4:IPv6=1:1)		| | with NAT44 and Stateless XLATE
	| CLAT |		| | (IPv4:IPv6=1:1).
	| | Case 2: CLAT will not have a
	| | dedicated IPv6 prefix
	| | -> NAT44 -> Stateless XLATE
	| | (IPv4:IPv6=1:1)
	+--------+		+--------+
	^ Source IPv4 address		^ Source IPv4 address
	| +----------------------------+		| +----------------------------+
	+--------+ | Private IPv4 address |		+--------+ | Private IPv4 address |
	| IPv4 | | assigned to IPv4 client |		| IPv4 | | assigned to IPv4 client |
	| client | +----------------------------+		| client | +----------------------------+
	+--------+ Destination IPv4 address		+--------+ Destination IPv4 address
	+----------------------------+		+----------------------------+
	| Global IPv4 address |		| Global IPv4 address |
	| assigned to IPv4 server |		| assigned to IPv4 server |
	+----------------------------+		+----------------------------+
	IPv4/IPv6 Address Translation Chart		Case of enabling NAT44 and stateless XLATE on CLAT
	7.3. Traffic Treatment Scenarios		7.3. IPv6 Prefix Handling
			7.3.1. Case of enabling only stateless XLATE on CLAT
			From the delegated DHCPv6 [RFC3633] prefix, a /64 is dedicated to
			source and receive IPv6 packets associated with the stateless
			translation [RFC6145].
			The CLAT MAY discover the Pref64::/n of the PLAT via some method such
			as DHCPv6 option, TR-069, DNS APL RR [RFC3123] or
			[I-D.ietf-behave-nat64-discovery-heuristic].
			7.3.2. Case of enabling NAT44 and stateless XLATE on CLAT
			In the case that DHCPv6-PD [RFC3633] is not available, the CLAT does
			not have dedicated IPv6 prefix for translation. If the CLAT does not
			have a dedicated IPv6 prefix for translation, the CLAT performs with
			NAT44 and stateless translation [RFC6145].
			Incoming source IPv4 packets from the LAN of [RFC1918] addresses are
			NAT44 to the CLAT IPv4 host address. Then, the CLAT will do a
			stateless translation [RFC6145] so that the IPv4 packets from the
			CLAT IPv4 host address are translated to the CLAT WAN IPv6 address as
			described in [RFC6052].
			Its subnet prefix is made of the delegated prefix, completed if
			needed to a /64 by a subnet ID = 0. Its interface ID is the 464XLAT
			interface ID (Section 10).
			The CLAT MAY discover the Pref64::/n of the PLAT via some method such
			as TR-069, DNS APL RR [RFC3123] or
			[I-D.ietf-behave-nat64-discovery-heuristic].
			7.4. Traffic Treatment Scenarios
	+--------+-------------+-----------------------+-------------+		+--------+-------------+-----------------------+-------------+
	| Server | Application | Traffic Treatment | Location of |		| Server | Application | Traffic Treatment | Location of |
	| | and Host | | Translation |		| | and Host | | Translation |
	+--------+-------------+-----------------------+-------------+		+--------+-------------+-----------------------+-------------+
	| IPv6 | IPv6 | End-to-end IPv6 | None |		| IPv6 | IPv6 | End-to-end IPv6 | None |
	+--------+-------------+-----------------------+-------------+		+--------+-------------+-----------------------+-------------+
	| IPv4 | IPv6 | Stateful Translation | PLAT |		| IPv4 | IPv6 | Stateful Translation | PLAT |
	+--------+-------------+-----------------------+-------------+		+--------+-------------+-----------------------+-------------+
	| IPv4 | IPv4 | 464XLAT | PLAT/CLAT |		| IPv4 | IPv4 | 464XLAT | PLAT/CLAT |
	+--------+-------------+-----------------------+-------------+		+--------+-------------+-----------------------+-------------+
	| IPv6 | IPv4 | Stateless Translation | CLAT |		| IPv6 | IPv4 | Stateless Translation | CLAT |
	+--------+-------------+-----------------------+-------------+		+--------+-------------+-----------------------+-------------+
	Traffic Treatment Scenarios		Traffic Treatment Scenarios
	The above chart shows most common traffic types and traffic		The above chart shows most common traffic types and traffic
	treatment.		treatment.
	7.4. DNS Proxy Implementation		7.5. DNS Proxy Implementation
	The CLAT SHOULD implement a DNS proxy as defined in [RFC5625]. The		The CLAT SHOULD implement a DNS proxy as defined in [RFC5625]. The
	case of an IPv4-only node behind CLAT querying an IPv4 DNS server is		case of an IPv4-only node behind CLAT querying an IPv4 DNS server is
	undesirable since it requires both stateful and stateless translation		undesirable since it requires both stateful and stateless translation
	for each DNS lookup. The CLAT SHOULD set itself as the DNS server		for each DNS lookup. The CLAT SHOULD set itself as the DNS server
	via DHCP or other means and proxy DNS queries for IPv4 and IPv6		via DHCP or other means and proxy DNS queries for IPv4 and IPv6
	clients. Using the CLAT enabled home router or UE as a DNS proxy is		clients. Using the CLAT enabled home router or UE as a DNS proxy is
	a normal consume gateway function and simplifies the traffic flow so		a normal consume gateway function and simplifies the traffic flow so
	that only IPv6 native queries are made across the access network.		that only IPv6 native queries are made across the access network.
	The CLAT SHOULD allow for a client to query any DNS server of its		The CLAT SHOULD allow for a client to query any DNS server of its
	choice and bypass the proxy.		choice and bypass the proxy.
	7.5. IPv6 Prefix Handling		7.6. CLAT in a Gateway
	From the delegated DHCPv6 [RFC3633] prefix, a /64 is dedicated to
	source and receive IPv6 packets associated with the stateless
	translation [RFC6145].
	In another cases where the access network does not allow for a
	dedicated translation prefix, the CLAT will do NAT44 such that all
	private IPv4 sourced LAN packets appears from one private IPv4
	address which is statelessly translated to one IPv6 address.
	The CLAT MAY discover the Pref64::/n of the PLAT via some method such
	as DHCPv6 option, TR-069, DNS APL RR [RFC3123] or
	[I-D.ietf-behave-nat64-discovery-heuristic].
	7.6. Relationship between CLAT and NAT44
	If the CLAT does not have dedicated IPv6 prefix for translation, the
	CLAT does NAT44 as an internal function which never appears on the
	wire.
	Incoming source IPv4 packets from the LAN of [RFC1918] addresses are
	NAT44 to the CLAT host address on the LAN of one [RFC1918] address.
	Then, the CLAT will do a stateless translation [RFC6145] so that the
	IPv4 packets from one [RFC1918] address are translated to the CLAT
	LAN IPv6 address as described in [RFC6052].
	7.7. CLAT in a Gateway
	The CLAT is a stateless translation feature which can be implemented		The CLAT is a stateless translation feature which can be implemented
	in a common home router or mobile phone that has a mobile router		in a common home router or mobile phone that has a mobile router
	feature. The router with CLAT function SHOULD provide common router		feature. The router with CLAT function SHOULD provide common router
	services such as DHCP of [RFC1918] addresses, DHCPv6, and DNS		services such as DHCP of [RFC1918] addresses, DHCPv6, and DNS
	service. The router SHOULD set itself as the DNS server advertised		service. The router SHOULD set itself as the DNS server advertised
	via DHCP or other means to the clients so that it may implement the		via DHCP or other means to the clients so that it may implement the
	DNS proxy function to avoid double translation of DNS request.		DNS proxy function to avoid double translation of DNS request.
	7.8. CLAT to CLAT communications		7.7. CLAT to CLAT communications
	While CLAT to CLAT IPv4 communication may work when the client IPv4		While CLAT to CLAT IPv4 communication may work when the client IPv4
	subnets do not overlap, this traffic flow is out of scope. 464XLAT is		subnets do not overlap, this traffic flow is out of scope. 464XLAT is
	a hub and spoke architecture focused on enabling IPv4-only services		a hub and spoke architecture focused on enabling IPv4-only services
	over IPv6-only access networks.		over IPv6-only access networks.
	8. Deployment Considerations		8. Deployment Considerations
	Even if the Internet access provider for consumers is different from		Even if the Internet access provider for consumers is different from
	the PLAT provider (another Internet access provider or Internet		the PLAT provider (e.g. another internet access provider), it can
	exchange provider, etc.), it can implement traffic engineering		implement traffic engineering independently from the PLAT provider.
	independently from the PLAT provider. Detailed reasons are below:		Detailed reasons are below:
	1. The Internet access provider for consumers can figure out IPv4		1. The Internet access provider for consumers can figure out IPv4
	source address and IPv4 destination address from translated IPv6		destination address from translated IPv6 packet header, so it can
	packet header, so it can implement traffic engineering based on		implement traffic engineering based on IPv4 destination address
	IPv4 source address and IPv4 destination address (e.g. traffic		(e.g. traffic monitoring for each IPv4 destination address,
	monitoring for each IPv4 destination address, packet filtering		packet filtering for each IPv4 destination address, etc.). The
	for each IPv4 destination address, etc.). The tunneling methods		tunneling methods do not have such a advantage, without any deep
	do not have such a advantage, without any deep packet inspection		packet inspection for processing the inner IPv4 packet of the
	for processing the inner IPv4 packet of the tunnel packet.		tunnel packet.
	2. If the Internet access provider for consumers can assign IPv6		2. If the Internet access provider for consumers can assign IPv6
	prefix greater than /64 for each subscriber, this 464XLAT		prefix greater than /64 for each subscriber, this 464XLAT
	architecture can separate IPv6 prefix for native IPv6 packets and		architecture can separate IPv6 prefix for native IPv6 packets and
	XLAT prefix for IPv4/IPv6 translation packets. Accordingly, it		XLAT prefix for IPv4/IPv6 translation packets. Accordingly, it
	can identify the type of packets ("native IPv6 packets" and		can identify the type of packets ("native IPv6 packets" and
	"IPv4/IPv6 translation packets"), and implement traffic		"IPv4/IPv6 translation packets"), and implement traffic
	engineering based on IPv6 prefix.		engineering based on IPv6 prefix.
	This 464XLAT architecture has two capabilities. One is a IPv4 ->		This 464XLAT architecture has two capabilities. One is a IPv4 ->
	IPv6 -> IPv4 translation for sharing global IPv4 addresses, another		IPv6 -> IPv4 translation for sharing global IPv4 addresses, another,
	is a IPv4 -> IPv6 translation for reaching IPv6-only servers from		if combined with BIH [RFC6535], is a IPv4 -> IPv6 translation for
	IPv4-only clients that can not support IPv6. IPv4-only clients must		reaching IPv6-only servers from IPv4-only clients that can not
	be support through the long period of global transition to IPv6.		support IPv6. IPv4-only clients must be support through the long
			period of global transition to IPv6.
	9. Security Considerations		9. Security Considerations
	To implement a PLAT, see security considerations presented in Section		To implement a PLAT, see security considerations presented in Section
	5 of [RFC6146].		5 of [RFC6146].
	To implement a CLAT, see security considerations presented in Section		To implement a CLAT, see security considerations presented in Section
	7 of [RFC6145]. The CLAT MAY comply with [RFC6092].		7 of [RFC6145]. The CLAT MAY comply with [RFC6092].
	10. IANA Considerations		10. IANA Considerations
	This document has no actions for IANA.		IANA is requested to reserve a Modified EUI-64 identifier for 464XLAT
			according to section 2.2.2 of [RFC5342]. Its suggested value is 02-
			00-5E-00-00-00-00-00 to 02-00-5E-0F-FF-FF-FF-FF or 02-00-5E-10-00-00-
			00-00 to 02-00-5E-EF-FF-FF-FF-FF, depending on whether it should be
			taken in reserved or available values.
	11. Acknowledgements		11. Acknowledgements
	The authors would like to thank JPIX NOC members, JPIX 464XLAT trial		The authors would like to thank JPIX NOC members, JPIX 464XLAT trial
	service members, Seiichi Kawamura, Dan Drown, Brian Carpenter, Rajiv		service members, Seiichi Kawamura, Dan Drown, Brian Carpenter, Rajiv
	Asati, Washam Fan, Behcet Sarikaya, Jan Zorz, Remi Despres, Tatsuya		Asati, Washam Fan, Behcet Sarikaya, Jan Zorz, Tatsuya Oishi, Lorenzo
	Oishi, Lorenzo Colitti, Erik Kline, Ole Troan, Maoke Chen, and Gang		Colitti, Erik Kline, Ole Troan, Maoke Chen, and Gang Chen for their
	Chen for their helpful comments. We also would like to thank Fred		helpful comments. Special acknowledgments go to Remi Despres for his
	Baker and Joel Jaeggli for their support.		plentiful supports and suggestions, especially about using NAT44 with
			IANA's EUI-64 ID. We also would like to thank Fred Baker and Joel
			Jaeggli for their support.
	12. References		12. References
	12.1. Normative References		12.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.		[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
	Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,		Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
	skipping to change at page 14, line 4		skipping to change at page 15, line 8
	[I-D.hazeyama-widecamp-ipv6-only-experience]		[I-D.hazeyama-widecamp-ipv6-only-experience]
	Hazeyama, H., Hiromi, R., Ishihara, T., and O. Nakamura,		Hazeyama, H., Hiromi, R., Ishihara, T., and O. Nakamura,
	"Experiences from IPv6-Only Networks with Transition		"Experiences from IPv6-Only Networks with Transition
	Technologies in the WIDE Camp Spring 2012",		Technologies in the WIDE Camp Spring 2012",
	draft-hazeyama-widecamp-ipv6-only-experience-01 (work in		draft-hazeyama-widecamp-ipv6-only-experience-01 (work in
	progress), March 2012.		progress), March 2012.
	[I-D.ietf-behave-nat64-discovery-heuristic]		[I-D.ietf-behave-nat64-discovery-heuristic]
	Savolainen, T., Korhonen, J., and D. Wing, "Discovery of		Savolainen, T., Korhonen, J., and D. Wing, "Discovery of
	IPv6 Prefix Used for IPv6 Address Synthesis",		IPv6 Prefix Used for IPv6 Address Synthesis",
	draft-ietf-behave-nat64-discovery-heuristic-07 (work in		draft-ietf-behave-nat64-discovery-heuristic-09 (work in
	progress), March 2012.		progress), May 2012.
	[I-D.mdt-softwire-mapping-address-and-port]
	Bao, C., Troan, O., Matsushima, S., Murakami, T., and X.
	Li, "Mapping of Address and Port (MAP)",
	draft-mdt-softwire-mapping-address-and-port-03 (work in
	progress), January 2012.
	[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and		[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
	E. Lear, "Address Allocation for Private Internets",		E. Lear, "Address Allocation for Private Internets",
	BCP 5, RFC 1918, February 1996.		BCP 5, RFC 1918, February 1996.
	[RFC3123] Koch, P., "A DNS RR Type for Lists of Address Prefixes		[RFC3123] Koch, P., "A DNS RR Type for Lists of Address Prefixes
	(APL RR)", RFC 3123, June 2001.		(APL RR)", RFC 3123, June 2001.
	[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic		[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
	Host Configuration Protocol (DHCP) version 6", RFC 3633,		Host Configuration Protocol (DHCP) version 6", RFC 3633,
	December 2003.		December 2003.
			[RFC5342] Eastlake, D., "IANA Considerations and IETF Protocol Usage
			for IEEE 802 Parameters", BCP 141, RFC 5342,
			September 2008.
	[RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines",		[RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines",
	BCP 152, RFC 5625, August 2009.		BCP 152, RFC 5625, August 2009.
	[RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in		[RFC6092] Woodyatt, J., "Recommended Simple Security Capabilities in
	Customer Premises Equipment (CPE) for Providing		Customer Premises Equipment (CPE) for Providing
	Residential IPv6 Internet Service", RFC 6092,		Residential IPv6 Internet Service", RFC 6092,
	January 2011.		January 2011.
	[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van		[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van
	Beijnum, "DNS64: DNS Extensions for Network Address		Beijnum, "DNS64: DNS Extensions for Network Address
	Translation from IPv6 Clients to IPv4 Servers", RFC 6147,		Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
	April 2011.		April 2011.
	[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
	Stack Lite Broadband Deployments Following IPv4
	Exhaustion", RFC 6333, August 2011.
	[RFC6459] Korhonen, J., Soininen, J., Patil, B., Savolainen, T.,		[RFC6459] Korhonen, J., Soininen, J., Patil, B., Savolainen, T.,
	Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation		Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
	Partnership Project (3GPP) Evolved Packet System (EPS)",		Partnership Project (3GPP) Evolved Packet System (EPS)",
	RFC 6459, January 2012.		RFC 6459, January 2012.
	[RFC6586] Arkko, J. and A. Keranen, "Experiences from an IPv6-Only		[RFC6535] Huang, B., Deng, H., and T. Savolainen, "Dual-Stack Hosts
	Network", RFC 6586, April 2012.		Using "Bump-in-the-Host" (BIH)", RFC 6535, February 2012.
			Appendix A. Examples of IPv4/IPv6 Address Translation
			The following are examples of IPv4/IPv6 Address Translation on the
			464XLAT architecture.
			Example 1. (Case of enabling only stateless XLATE on CLAT)
			In the case that IPv6 prefix greater than /64 is assigned to end
			users by such as DHCPv6-PD [RFC3633], only the function of Stateless
			XLATE should be enabled on CLAT. Because the CLAT can use dedicated
			a /64 from the assigned IPv6 prefix for Stateless XLATE.
			Host & configuration value
			+------------------------------+
			| IPv4 server |
			| [198.51.100.1] | IP packet header
			+------------------------------+ +--------------------------------+
			^ | Source IP address |
			| | [192.0.2.1] |
			| | Destination IP address |
			| | [198.51.100.1] |
			+------------------------------+ +--------------------------------+
			| PLAT | ^
			| IPv4 pool address | |
			| [192.0.2.1 - 192.0.2.100] | |
			| PLAT-side XLATE IPv6 prefix | |
			| [2001:db8:1234::/96] | |
			+------------------------------+ +--------------------------------+
			^ | Source IP address |
			| | [2001:db8:aaaa::192.168.1.2] |
			| | Destination IP address |
			| | [2001:db8:1234::198.51.100.1] |
			+------------------------------+ +--------------------------------+
			| CLAT | ^
			| PLAT-side XLATE IPv6 prefix | |
			| [2001:db8:1234::/96] | |
			| CLAT-side XLATE IPv6 prefix | |
			| [2001:db8:aaaa::/96] | |
			+------------------------------+ +--------------------------------+
			^ | Source IP address |
			| | [192.168.1.2] |
			| | Destination IP address |
			| | [198.51.100.1] |
			+------------------------------+ +--------------------------------+
			| IPv4 client |
			| [192.168.1.2/24] |
			+------------------------------+
			Delegated IPv6 prefix for client: 2001:db8:aaaa::/56
			Example 1. (Case of enabling only stateless XLATE on CLAT)
			Example 2. (Case of enabling NAT44 and stateless XLATE on CLAT)
			In the case that IPv6 prefix /64 is assigned to end users, the
			function of NAT44 and Stateless XLATE should be enabled on CLAT.
			Because the CLAT does not have dedicated IPv6 prefix for translation.
			Host & configuration value
			+-------------------------------+
			| IPv4 server |
			| [198.51.100.1] | IP packet header
			+-------------------------------+ +-------------------------------+
			^ | Source IP address |
			| | [192.0.2.1] |
			| | Destination IP address |
			| | [198.51.100.1] |
			+-------------------------------+ +-------------------------------+
			| PLAT | ^
			| IPv4 pool address | |
			| [192.0.2.1 - 192.0.2.100] | |
			| PLAT-side XLATE IPv6 prefix | |
			| [2001:db8:1234::/96] | |
			+-------------------------------+ +-------------------------------+
			^ | Source IP address |
			| | [2001:db8:aaaa:200:5e10:0:0] |
			| | Destination IP address |
			| | [2001:db8:1234::198.51.100.1] |
			| +-------------------------------+
			+-------------------------------+ ^
			| CLAT Stateless XLATE function | |
			| - - - - - - - - - - - - - - - | |
			| PLAT-side XLATE IPv6 prefix | |
			| [2001:db8:1234::/96] | |
			| CLAT-side XLATE IPv6 prefix | |
			| [2001:db8:aaaa::/64] | |
			| CLAT-side XLATE IPv6 EUI-64 ID| |
			| [02-00-5E-10-00-00-00-00] | |
			+ - - - - - - - - - - - - - - - + +-------------------------------+
			| ^ | | Source IP address |
			| | | | [10.255.255.1] |
			| | | | Destination IP address |
			| | | | [198.51.100.1] |
			+ - - - - - - - - - - - - - - - + +-------------------------------+
			| CLAT NAT44 function | ^
			| - - - - - - - - - - - - - - - | |
			| NAT44 NATed address | |
			| [10.255.255.1/32] | |
			+-------------------------------+ |
			^ +-------------------------------+
			| | Source IP address |
			| | [192.168.1.2] |
			| | Destination IP address |
			| | [198.51.100.1] |
			+-------------------------------+ +-------------------------------+
			| IPv4 client |
			| [192.168.1.2/24] |
			+-------------------------------+
			Delegated IPv6 prefix for client: 2001:db8:aaaa::/64
			Example 2. (Case of enabling NAT44 and stateless XLATE on CLAT)
	Authors' Addresses		Authors' Addresses
	Masataka Mawatari		Masataka Mawatari
	Japan Internet Exchange Co.,Ltd.		Japan Internet Exchange Co.,Ltd.
	KDDI Otemachi Building 19F, 1-8-1 Otemachi,		KDDI Otemachi Building 19F, 1-8-1 Otemachi,
	Chiyoda-ku, Tokyo 100-0004		Chiyoda-ku, Tokyo 100-0004
	JAPAN		JAPAN
	Phone: +81 3 3243 9579		Phone: +81 3 3243 9579
End of changes. 43 change blocks.
	237 lines changed or deleted		338 lines changed or added
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