draft-ietf-v6ops-3gpp-cases-03.txt		rfc3574.txt
	Internet Draft J. Soininen (ed.)		Network Working Group J. Soininen, Ed.
	Document: draft-ietf-v6ops-3gpp-cases-03.txt Nokia		Request for Comments: 3574 Nokia
	Expires: September 2003 March 2003		Category: Informational August 2003
	Transition Scenarios for 3GPP Networks		Transition Scenarios for 3GPP Networks
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is in full conformance with		This memo provides information for the Internet community. It does
	all provisions of Section 10 of RFC2026.		not specify an Internet standard of any kind. Distribution of this
			memo is unlimited.
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	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2003). All Rights Reserved.		Copyright (C) The Internet Society (2003). All Rights Reserved.
	Abstract		Abstract
	This document describes different scenarios in Third Generation		This document describes different scenarios in Third Generation
	Partnership Project (3GPP) defined packet network, i.e. General		Partnership Project (3GPP) defined packet network, i.e., General
	Packet Radio Service (GPRS) that would need IP version 6 and IP		Packet Radio Service (GPRS) that would need IP version 6 and IP
	version 4 transition. The focus of this document is on the scenarios		version 4 transition. The focus of this document is on the scenarios
	where the User Equipment (UE) connects to nodes in other networks,		where the User Equipment (UE) connects to nodes in other networks,
	e.g. in the Internet. GPRS network internal transition scenarios,		e.g., in the Internet. GPRS network internal transition scenarios,
	i.e. between different GPRS elements in the network, are out of		i.e., between different GPRS elements in the network, are out of
	scope.		scope. The purpose of the document is to list the scenarios for
			further discussion and study.
	The purpose of the document is to list the scenarios for further
	discussion and study.
	Table of Contents		Table of Contents
	1. Introduction...................................................2		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
	2. Scope of the Document..........................................2		2. Scope of the Document. . . . . . . . . . . . . . . . . . . . . 2
	3. Brief Description of the 3GPP Network Environment..............3		3. Brief Description of the 3GPP Network Environment. . . . . . . 2
	3.1 GPRS Architecture Basics...................................3		3.1 GPRS Architecture Basics . . . . . . . . . . . . . . . . . 3
	3.2 IP Multimedia Core Network Subsystem (IMS).................4		3.2 IP Multimedia Core Network Subsystem (IMS) . . . . . . . . 3
	4. Transition Scenarios...........................................5		4. Transition Scenarios . . . . . . . . . . . . . . . . . . . . . 5
	4.1 GPRS Scenarios.............................................5		4.1 GPRS Scenarios . . . . . . . . . . . . . . . . . . . . . . 5
	4.2 IMS Scenarios..............................................8		4.2 IMS Scenarios . . . . . . . . . . . . . . . . . . . . . . 8
	5. Security Considerations........................................9		5. Security Considerations. . . . . . . . . . . . . . . . . . . . 9
	Authors..........................................................10		6. Contributing Authors . . . . . . . . . . . . . . . . . . . . . 10
	Normative References.............................................11		7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
	Informative references...........................................11		8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
	Editor's Address.................................................11		8.1. Normative References . . . . . . . . . . . . . . . . . . 10
			8.2. Informative References . . . . . . . . . . . . . . . . . 11
	Copyright		9. Editor's Address . . . . . . . . . . . . . . . . . . . . . . . 11
			10. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 12
	(C) The Internet Society (2003). All Rights Reserved.
	1. Introduction		1. Introduction
	This document describes the transition scenarios in 3GPP packet data		This document describes the transition scenarios in 3GPP packet data
	networks that might come up in the deployment phase of IPv6. The		networks that might come up in the deployment phase of IPv6. The
	main purpose of this document is to identify and to document those		main purpose of this document is to identify and to document those
	scenarios for further discussion and study them in the v6ops working		scenarios for further discussion and study them in the v6ops working
	group.		group.
	Just a brief overview of the 3GPP packet data network, GPRS, is given		Just a brief overview of the 3GPP packet data network, GPRS, is given
	skipping to change at page 2, line 47		skipping to change at page 2, line 27
	2. Scope of the Document		2. Scope of the Document
	The scope is to describe the possible transition scenarios in the		The scope is to describe the possible transition scenarios in the
	3GPP defined GPRS network where a UE connects to, or is contacted		3GPP defined GPRS network where a UE connects to, or is contacted
	from, the Internet or another UE. The document describes scenarios		from, the Internet or another UE. The document describes scenarios
	with and without the usage of the SIP-based (Session Initiation		with and without the usage of the SIP-based (Session Initiation
	Protocol [5]) IP Multimedia Core Network Subsystem (IMS). The 3GPP		Protocol [5]) IP Multimedia Core Network Subsystem (IMS). The 3GPP
	releases 1999, 4, and 5 are considered as the basis.		releases 1999, 4, and 5 are considered as the basis.
	Out of scope are scenarios inside the GPRS network, i.e. on the		Out of scope are scenarios inside the GPRS network, i.e., on the
	different interfaces of the GPRS network. This document neither		different interfaces of the GPRS network. This document neither
	changes 3GPP specifications, nor proposes changes to the current		changes 3GPP specifications, nor proposes changes to the current
	specifications.		specifications.
	In addition, the possible transition scenarios are described. The		In addition, the possible transition scenarios are described. The
	solutions will be documented in a separate document.		solutions will be documented in a separate document.
	All the possible scenarios are listed here. Further analysis may show		All the possible scenarios are listed here. Further analysis may
	that some of the scenarios are not actually relevant in this context.		show that some of the scenarios are not actually relevant in this
			context.
	3. Brief Description of the 3GPP Network Environment		3. Brief Description of the 3GPP Network Environment
	This section describes the most important concepts of the 3GPP		This section describes the most important concepts of the 3GPP
	environment for understanding the transition scenarios. The first		environment for understanding the transition scenarios. The first
	part of the description gives a brief overview to the GPRS network as		part of the description gives a brief overview to the GPRS network as
	such. The second part concentrates on the IP Multimedia Core Network		such. The second part concentrates on the IP Multimedia Core Network
	Subsystem (IMS).		Subsystem (IMS).
	3.1 GPRS Architecture Basics		3.1. GPRS Architecture Basics
	This section gives an overview to the most important concepts of the		This section gives an overview to the most important concepts of the
	3GPP packet architecture. For more detailed description, please see		3GPP packet architecture. For more detailed description, please see
	[1].		[1].
	From the point of view of this document, the most relevant 3GPP		From the point of view of this document, the most relevant 3GPP
	architectural elements are the User Equipment (UE), and the Gateway		architectural elements are the User Equipment (UE), and the Gateway
	GPRS Support Node (GGSN). A simplified picture of the architecture is		GPRS Support Node (GGSN). A simplified picture of the architecture
	shown in Figure 1.		is shown in Figure 1.
	The UE is the mobile phone. It can either be an integrated device		The UE is the mobile phone. It can either be an integrated device
	comprising a combined GPRS part, and the IP stack, or it might be a		comprising a combined GPRS part, and the IP stack, or it might be a
	separate GPRS device, and separate equipment with the IP stack, e.g.		separate GPRS device, and separate equipment with the IP stack, e.g.,
	a laptop.		a laptop.
	The GGSN serves as an anchor-point for the GPRS mobility management.		The GGSN serves as an anchor-point for the GPRS mobility management.
	It also serves as the default router for the UE.		It also serves as the default router for the UE.
	The Peer node mentioned in the picture refers to a node with which		The Peer node mentioned in the picture refers to a node with which
	the UE is communicating.		the UE is communicating.
	-- ---- ************ ---------		-- ---- ************ ---------
	|UE|- ... -|GGSN|--+--* IPv4/v6 NW *--+--|Peer node|		|UE|- ... -|GGSN|--+--* IPv4/v6 NW *--+--|Peer node|
	skipping to change at page 3, line 44		skipping to change at page 3, line 30
	The GGSN serves as an anchor-point for the GPRS mobility management.		The GGSN serves as an anchor-point for the GPRS mobility management.
	It also serves as the default router for the UE.		It also serves as the default router for the UE.
	The Peer node mentioned in the picture refers to a node with which		The Peer node mentioned in the picture refers to a node with which
	the UE is communicating.		the UE is communicating.
	-- ---- ************ ---------		-- ---- ************ ---------
	|UE|- ... -|GGSN|--+--* IPv4/v6 NW *--+--|Peer node|		|UE|- ... -|GGSN|--+--* IPv4/v6 NW *--+--|Peer node|
	-- ---- ************ ---------		-- ---- ************ ---------
	Figure 1: Simplified GPRS Architecture		Figure 1: Simplified GPRS Architecture
	There is a dedicated link between the UE and the GGSN called the		There is a dedicated link between the UE and the GGSN called the
	Packet Data Protocol (PDP) Context. This link is created through the		Packet Data Protocol (PDP) Context. This link is created through the
	PDP Context activation process. During the activation the UE is		PDP Context activation process. During the activation the UE is
	configured with its IP address and other information needed to		configured with its IP address and other information needed to
	maintain IP access, e.g. DNS server address. There are three		maintain IP access, e.g., DNS server address. There are three
	different types of PDP Contexts: IPv4, IPv6, and Point-to-Point		different types of PDP Contexts: IPv4, IPv6, and Point-to-Point
	Protocol (PPP).		Protocol (PPP).
	A UE can have one or more simultaneous PDP Contexts open to the same		A UE can have one or more simultaneous PDP Contexts open to the same
	or to different GGSNs. The PDP Context can be either of the same or		or to different GGSNs. The PDP Context can be either of the same or
	different types.		different types.
	3.2 IP Multimedia Core Network Subsystem (IMS)		3.2. IP Multimedia Core Network Subsystem (IMS)
	IP Multimedia Core Network Subsystem (IMS) is an architecture for		IP Multimedia Core Network Subsystem (IMS) is an architecture for
	supporting multimedia services via a SIP infrastructure. It is		supporting multimedia services via a SIP infrastructure. It is
	specified in 3GPP Release 5. This section provides an overview of the		specified in 3GPP Release 5. This section provides an overview of
	3GPP IMS and is not intended to be comprehensive. A more detailed		the 3GPP IMS and is not intended to be comprehensive. A more
	description can be found in [2], [3] and [4].		detailed description can be found in [2], [3] and [4].
	The IMS comprises a set of SIP proxies, servers, and registrars. In		The IMS comprises a set of SIP proxies, servers, and registrars. In
	addition, there are Media Gateways (MGWs) that offer connections to		addition, there are Media Gateways (MGWs) that offer connections to
	non-IP networks such as the Public Switched Telephony Network (PSTN).		non-IP networks such as the Public Switched Telephony Network (PSTN).
	A simplified overview of the IMS is depicted in figure 2.		A simplified overview of the IMS is depicted in figure 2.
	+-------------+ +-------------------------------------+		+-------------+ +-------------------------------------+
	| | | +------+ |		| | | +------+ |
	| | | |S-CSCF|---		| | | |S-CSCF|---
	| | | | +------+ |		| | | | +------+ |
	skipping to change at page 4, line 52		skipping to change at page 4, line 41
	- I-CSCF (Interrogating-CSCF) is the contact point within an		- I-CSCF (Interrogating-CSCF) is the contact point within an
	operator's network for all connections destined to a subscriber		operator's network for all connections destined to a subscriber
	of that network operator, or a roaming subscriber currently		of that network operator, or a roaming subscriber currently
	located within that network operator's service area.		located within that network operator's service area.
	- S-CSCF (Serving-CSCF) performs the session control services for		- S-CSCF (Serving-CSCF) performs the session control services for
	the subscriber. It also acts as a SIP Registrar.		the subscriber. It also acts as a SIP Registrar.
	IMS capable UEs utilize the GPRS network as an access network for		IMS capable UEs utilize the GPRS network as an access network for
	accessing the IMS. Thus, a UE has to have an activated PDP Context to		accessing the IMS. Thus, a UE has to have an activated PDP Context
	the IMS before it can proceed to use the IMS services. The PDP		to the IMS before it can proceed to use the IMS services. The PDP
	Context activation is explained briefly in section 3.1.		Context activation is explained briefly in section 3.1.
	The IMS is exclusively IPv6. Thus, the activated PDP Context is of		The IMS is exclusively IPv6. Thus, the activated PDP Context is of
	PDP Type IPv6. This means that a 3GPP IP Multimedia terminal uses		PDP Type IPv6. This means that a 3GPP IP Multimedia terminal uses
	exclusively IPv6 to access the IMS, and the IMS SIP server and proxy		exclusively IPv6 to access the IMS, and the IMS SIP server and proxy
	support exclusively IPv6. Hence, all the traffic going to the IMS is		support exclusively IPv6. Hence, all the traffic going to the IMS is
	IPv6, even if the UE is dual stack capable - this comprises both		IPv6, even if the UE is dual stack capable - this comprises both
	signaling and user traffic.		signaling and user traffic.
	This, of course, does not prevent the usage of other unrelated		This, of course, does not prevent the usage of other unrelated
	services (e.g. corporate access) on IPv4.		services (e.g., corporate access) on IPv4.
	4. Transition Scenarios		4. Transition Scenarios
	This section is divided into two main parts - GPRS scenarios, and		This section is divided into two main parts - GPRS scenarios, and
	scenarios with the IP Multimedia Subsystem (IMS). The first part -		scenarios with the IP Multimedia Subsystem (IMS). The first part -
	GPRS scenarios - concentrates on scenarios with a User Equipment (UE)		GPRS scenarios - concentrates on scenarios with a User Equipment (UE)
	connecting to services in the Internet, e.g. mail, web. The second		connecting to services in the Internet, e.g., mail, web. The second
	part - IMS scenarios - then describes how an IMS capable UE can		part - IMS scenarios - then describes how an IMS capable UE can
	connect to other SIP-capable nodes in the Internet using the IMS		connect to other SIP-capable nodes in the Internet using the IMS
	services.		services.
	4.1 GPRS Scenarios		4.1. GPRS Scenarios
	This section describes the scenarios that might occur when a GPRS UE		This section describes the scenarios that might occur when a GPRS UE
	contacts services, or nodes outside the GPRS network, e.g. web-server		contacts services, or nodes outside the GPRS network, e.g., web-
	in the Internet.		server in the Internet.
	Transition scenarios of the GPRS internal interfaces are outside of		Transition scenarios of the GPRS internal interfaces are outside of
	the scope of this document.		the scope of this document.
	The following scenarios are described here. In all of the scenarios,		The following scenarios are described here. In all of the scenarios,
	the UE is part of a network where there is at least one router of the		the UE is part of a network where there is at least one router of the
	same IP version, i.e. GGSN, and it is connecting to a node in a		same IP version, i.e., GGSN, and it is connecting to a node in a
	different network.		different network.
	The scenarios here apply also for PDP Context type Point-to-Point		The scenarios here apply also for PDP Context type Point-to-Point
	Protocol (PPP) where PPP is terminated at the GGSN. On the other		Protocol (PPP) where PPP is terminated at the GGSN. On the other
	hand, where the PPP PDP Context is terminated e.g. at an external		hand, where the PPP PDP Context is terminated e.g., at an external
	ISP, the environment is the same as for general ISP cases.		ISP, the environment is the same as for general ISP cases.
	1) Dual Stack UE connecting to IPv4 and IPv6 nodes		1) Dual Stack UE connecting to IPv4 and IPv6 nodes
	2) IPv6 UE connecting to an IPv6 node through an IPv4 network		2) IPv6 UE connecting to an IPv6 node through an IPv4 network
	3) IPv4 UE connecting to an IPv4 node through an IPv6 network		3) IPv4 UE connecting to an IPv4 node through an IPv6 network
	4) IPv6 UE connecting to an IPv4 node		4) IPv6 UE connecting to an IPv4 node
	5) IPv4 UE connecting to an IPv6 node		5) IPv4 UE connecting to an IPv6 node
	1) Dual Stack UE connecting to IPv4 and IPv6 nodes		1) Dual Stack UE connecting to IPv4 and IPv6 nodes
	The GPRS system has been designed in a manner that there is the		The GPRS system has been designed in a manner that there is the
	possibility to have simultaneous IPv4, and IPv6 PDP Contexts open.		possibility to have simultaneous IPv4, and IPv6 PDP Contexts open.
	Thus, in cases where the UE is dual stack capable, and in the network		Thus, in cases where the UE is dual stack capable, and in the
	there is a GGSN (or separate GGSNs) that supports both connections to		network there is a GGSN (or separate GGSNs) that supports both
	IPv4 and IPv6 networks, it is possible to connect to both at the same		connections to IPv4 and IPv6 networks, it is possible to connect
	time. Figure 3 depicts this scenario.		to both at the same time. Figure 3 depicts this scenario.
	+-------------+		+-------------+
	| |		| |
	| UE | +------+		| UE | +------+
	| | | IPv4 |		| | | IPv4 |
	| | /| |		| | /| |
	|------|------+ / +------+		|------|------+ / +------+
	| IPv6 | IPv4 | +--------+ /		| IPv6 | IPv4 | +--------+ /
	+-------------+ IPv4 | | /		+-------------+ IPv4 | | /
	| |------------------------| |/		| |------------------------| |/
	| | |		| | |
	| IPv6 | GGSN |\		| IPv6 | GGSN |\
	|-------------------------------| | \		|-------------------------------| | \
	+-----------+ | | \ +------+		+-----------+ | | \ +------+
	| GPRS Core | | | \ | IPv6 |		| GPRS Core | | | \ | IPv6 |
	+-----------+ +--------+ | |		+-----------+ +--------+ \| |
	+------+		+------+
	Figure 3: Dual-Stack Case		Figure 3: Dual-Stack Case
	However, the IPv4 addresses may be a scarce resource for the mobile		However, the IPv4 addresses may be a scarce resource for the
	operator or an ISP. In that case, it might not be possible for the UE		mobile operator or an ISP. In that case, it might not be possible
	to have a globally unique IPv4 address allocated all the time. Hence,		for the UE to have a globally unique IPv4 address allocated all
	the UE could either activate the IPv4 PDP Context only when needed,		the time. Hence, the UE could either activate the IPv4 PDP
	or be allocated an IPv4 address from a private address space.		Context only when needed, or be allocated an IPv4 address from a
			private address space.
	2) IPv6 UE connecting to an IPv6 node through an IPv4 network		2) IPv6 UE connecting to an IPv6 node through an IPv4 network
	Especially in the initial stages of IPv6 deployment, there are cases		Especially in the initial stages of IPv6 deployment, there are
	where an IPv6 node would need to connect to the IPv6 Internet through		cases where an IPv6 node would need to connect to the IPv6
	a network that is IPv4. For instance, this can be seen in current		Internet through a network that is IPv4. For instance, this can
	fixed networks, where the access is provided via IPv4 only, but there		be seen in current fixed networks, where the access is provided
	is an IPv6 network deeper in the Internet. This scenario is shown in		via IPv4 only, but there is an IPv6 network deeper in the
	Figure 4.		Internet. This scenario is shown in Figure 4.
	+------+ +------+		+------+ +------+
	| | | | +------+		| | | | +------+
	| UE |------------------| |-----------------| |		| UE |------------------| |-----------------| |
	| | +-----------+ | GGSN | +---------+ | IPv6 |		| | +-----------+ | GGSN | +---------+ | IPv6 |
	| IPv6 | | GPRS Core | | | | IPv4 Net| | |		| IPv6 | | GPRS Core | | | | IPv4 Net| | |
	+------+ +-----------+ +------+ +---------+ +------+		+------+ +-----------+ +------+ +---------+ +------+
	Figure 4: IPv6 nodes communicating over IPv4		Figure 4: IPv6 nodes communicating over IPv4
	In this case, in the GPRS system, the UE would be IPv6 capable, and		In this case, in the GPRS system, the UE would be IPv6 capable,
	the GPRS network would provide an IPv6 capable GGSN in the network.		and the GPRS network would provide an IPv6 capable GGSN in the
	However, there is an IPv4 network between the GGSN, and the peer		network. However, there is an IPv4 network between the GGSN, and
	node.		the peer node.
	3) IPv4 UE connecting to an IPv4 node through an IPv6 network		3) IPv4 UE connecting to an IPv4 node through an IPv6 network
	Further in the future, there are cases where the legacy UEs are still		Further in the future, there are cases where the legacy UEs are
	IPv4 only, capable of connecting only to the legacy IPv4 Internet.		still IPv4 only, capable of connecting only to the legacy IPv4
	However, the GPRS operator network has already been upgraded to IPv6.		Internet. However, the GPRS operator network has already been
	Figure 5 represents this scenario.		upgraded to IPv6. Figure 5 represents this scenario.
	+------+ +------+		+------+ +------+
	| | | | +------+		| | | | +------+
	| UE |------------------| |-----------------| |		| UE |------------------| |-----------------| |
	| | +-----------+ | GGSN | +---------+ | IPv4 |		| | +-----------+ | GGSN | +---------+ | IPv4 |
	| IPv4 | | GPRS Core | | | | IPv6 Net| | |		| IPv4 | | GPRS Core | | | | IPv6 Net| | |
	+------+ +-----------+ +------+ +---------+ +------+		+------+ +-----------+ +------+ +---------+ +------+
	Figure 5: IPv4 nodes communicating over IPv6		Figure 5: IPv4 nodes communicating over IPv6
	In this case, the operator would still provide an IPv4 capable GGSN,		In this case, the operator would still provide an IPv4 capable
	and a connection through the IPv6 network to the IPv4 Internet.		GGSN, and a connection through the IPv6 network to the IPv4
			Internet.
	4) IPv6 UE connecting to an IPv4 node		4) IPv6 UE connecting to an IPv4 node
	In this scenario, an IPv6 UE connects to an IPv4 node in the IPv4		In this scenario, an IPv6 UE connects to an IPv4 node in the IPv4
	Internet. As an example, an IPv6 UE connects to an IPv4 web server in		Internet. As an example, an IPv6 UE connects to an IPv4 web
	the legacy Internet. In the figure 6, this kind of possible		server in the legacy Internet. In the figure 6, this kind of
	installation is described.		possible installation is described.
	+------+ +------+		+------+ +------+
	| | | | +---+ +------+		| | | | +---+ +------+
	| UE |------------------| |-----| |----| |		| UE |------------------| |-----| |----| |
	| | +-----------+ | GGSN | | ? | | IPv4 |		| | +-----------+ | GGSN | | ? | | IPv4 |
	| IPv6 | | GPRS Core | | | | | | |		| IPv6 | | GPRS Core | | | | | | |
	+------+ +-----------+ +------+ +---+ +------+		+------+ +-----------+ +------+ +---+ +------+
	Figure 6: IPv6 node communicating with IPv4 node		Figure 6: IPv6 node communicating with IPv4 node
	5) IPv4 UE connecting to an IPv6 node		5) IPv4 UE connecting to an IPv6 node
	This is similar to the case above, but in the opposite direction.		This is similar to the case above, but in the opposite direction.
	Here an IPv4 UE connects to an IPv6 node in the IPv6 Internet. As an		Here an IPv4 UE connects to an IPv6 node in the IPv6 Internet. As
	example, a legacy IPv4 UE is connected to an IPv6 server in the IPv6		an example, a legacy IPv4 UE is connected to an IPv6 server in the
	Internet. Figure 7 depicts this configuration.		IPv6 Internet. Figure 7 depicts this configuration.
	+------+ +------+		+------+ +------+
	| | | | +---+ +------+		| | | | +---+ +------+
	| UE |------------------| |-----| |----| |		| UE |------------------| |-----| |----| |
	| | +-----------+ | GGSN | | ? | | IPv6 |		| | +-----------+ | GGSN | | ? | | IPv6 |
	| IPv4 | | GPRS Core | | | | | | |		| IPv4 | | GPRS Core | | | | | | |
	+------+ +-----------+ +------+ +---+ +------+		+------+ +-----------+ +------+ +---+ +------+
	Figure 7: IPv4 node communicating with IPv6 node		Figure 7: IPv4 node communicating with IPv6 node
	4.2 IMS Scenarios		4.2. IMS Scenarios
	As described in section 3.2, IMS is exclusively IPv6. Thus, the		As described in section 3.2, IMS is exclusively IPv6. Thus, the
	number of possible transition scenarios is reduced dramatically. In		number of possible transition scenarios is reduced dramatically. In
	the following, the possible transition scenarios are listed.		the following, the possible transition scenarios are listed.
	1) UE connecting to a node in an IPv4 network through IMS		1) UE connecting to a node in an IPv4 network through IMS
	2) Two IPv6 IMS connected via an IPv4 network		2) Two IPv6 IMS connected via an IPv4 network
	1) UE connecting to a node in an IPv4 network through IMS		1) UE connecting to a node in an IPv4 network through IMS
	This scenario occurs when an IMS UE (IPv6) connects to a node in the		This scenario occurs when an IMS UE (IPv6) connects to a node in
	IPv4 Internet through the IMS, or vice versa. This happens when the		the IPv4 Internet through the IMS, or vice versa. This happens
	other node is a part of a different system than 3GPP, e.g. a fixed		when the other node is a part of a different system than 3GPP,
	PC, with only IPv4 capabilities. This scenario is shown in the Figure		e.g., a fixed PC, with only IPv4 capabilities. This scenario is
	8.		shown in the Figure 8.
	+------+ +------+ +-----+		+------+ +------+ +-----+
	| | | | | | +---+ +------+		| | | | | | +---+ +------+
	| UE |-...-| |-----| IMS |--| |--| |		| UE |-...-| |-----| IMS |--| |--| |
	| | | GGSN | | | | ? | | IPv4 |		| | | GGSN | | | | ? | | IPv4 |
	| IPv6 | | | | | | | | |		| IPv6 | | | | | | | | |
	+------+ +------+ +-----+ +---+ +------+		+------+ +------+ +-----+ +---+ +------+
	Figure 8: IMS UE connecting to an IPv4 node		Figure 8: IMS UE connecting to an IPv4 node
	2) Two IPv6 IMS connected via an IPv4 network		2) Two IPv6 IMS connected via an IPv4 network
	At the early stages of IMS deployment, there may be cases where two		At the early stages of IMS deployment, there may be cases where
	IMS islands are only connected via an IPv4 network such as the legacy		two IMS islands are only connected via an IPv4 network such as the
	Internet. See Figure 9 for illustration.		legacy Internet. See Figure 9 for illustration.
	+------+ +------+ +-----+ +-----+		+------+ +------+ +-----+ +-----+
	| | | | | | | |		| | | | | | | |
	| UE |-...-| |-----| IMS |----------| |		| UE |-...-| |-----| IMS |----------| |
	| | | GGSN | | | +------+ | IMS |		| | | GGSN | | | +------+ | IMS |
	| IPv6 | | | | | | IPv4 | | |		| IPv6 | | | | | | IPv4 | | |
	+------+ +------+ +-----+ +------+ +-----+		+------+ +------+ +-----+ +------+ +-----+
	Figure 9: Two IMS islands connected over IPv4		Figure 9: Two IMS islands connected over IPv4
	5. Security Considerations		5. Security Considerations
	This document describes possible transition scenarios for 3GPP		This document describes possible transition scenarios for 3GPP
	networks for future study. Solutions and mechanism are explored in		networks for future study. Solutions and mechanism are explored in
	other documents: The description of the 3GPP network scenarios does		other documents. The description of the 3GPP network scenarios does
	not have any security considerations.		not have any security issues.
	Authors		6. Contributing Authors
	This document is a result of a joint effort of a design team. The		This document is a result of a joint effort of a design team. The
	members of the design team are listed in the following.		members of the design team are listed in the following.
	Alain Durand, Sun Microsystems		Alain Durand, Sun Microsystems
	<Alain.Durand@sun.com>		<Alain.Durand@sun.com>
	Karim El-Malki, Ericsson Radio Systems		Karim El-Malki, Ericsson Radio Systems
	<Karim.El-Malki@era.ericsson.se>		<Karim.El-Malki@era.ericsson.se>
	skipping to change at page 10, line 34		skipping to change at page 10, line 34
	Hesham Soliman, Ericsson Radio Systems		Hesham Soliman, Ericsson Radio Systems
	<hesham.soliman@era.ericsson.se>		<hesham.soliman@era.ericsson.se>
	Margaret Wasserman, Wind River		Margaret Wasserman, Wind River
	<mrw@windriver.com>		<mrw@windriver.com>
	Juha Wiljakka, Nokia		Juha Wiljakka, Nokia
	<juha.wiljakka@nokia.com>		<juha.wiljakka@nokia.com>
	Acknowledgements		7. Acknowledgements
	The authors would like to thank Basavaraj Patil, Tuomo Sipila, Fred		The authors would like to thank Basavaraj Patil, Tuomo Sipila, Fred
	Templin, Rod Van Meter, Pekka Savola, Francis Dupont, Christine		Templin, Rod Van Meter, Pekka Savola, Francis Dupont, Christine
	Fisher, Alain Baudot, Rod Walsh, and Jens Staack for good input, and		Fisher, Alain Baudot, Rod Walsh, and Jens Staack for good input, and
	comments that helped writing this document.		comments that helped writing this document.
	Normative References		8. References
			8.1. Normative References
	[1] 3GPP TS 23.060 v 5.2.0, "General Packet Radio Service (GPRS);		[1] 3GPP TS 23.060 v 5.2.0, "General Packet Radio Service (GPRS);
	Service description; Stage 2(Release 5)", June 2002.		Service description; Stage 2(Release 5)", June 2002.
	[2] 3GPP TS 23.228 v 5.3.0, " IP Multimedia Subsystem (IMS); Stage		[2] 3GPP TS 23.228 v 5.3.0, " IP Multimedia Subsystem (IMS); Stage
	2(Release 5)", January 2002.		2(Release 5)", January 2002.
	[3] 3GPP TS 24.228 V5.0.0, "Signalling flows for the IP multimedia		[3] 3GPP TS 24.228 V5.0.0, "Signalling flows for the IP multimedia
	call control based on SIP and SDP; Stage 3 (Release 5)", March		call control based on SIP and SDP; Stage 3 (Release 5)", March
	2002.		2002.
	[4] 3GPP TS 24.229 V5.0.0, "IP Multimedia Call Control Protocol		[4] 3GPP TS 24.229 V5.0.0, "IP Multimedia Call Control Protocol based
	based on SIP and SDP; Stage 3 (Release 5)", March 2002.		on SIP and SDP; Stage 3 (Release 5)", March 2002.
	[5] Rosenberg J., Schulzrinne H., Camarillo G., Johnston A.,		[5] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
	Peterson J., Sparks R., Handley M., Schooler E., " SIP: Session		Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP:
	Initiation Protocol", RFC3261, June 2002.		Session Initiation Protocol", RFC 3261, June 2002.
	Informative references		8.2. Informative References
	[6] Wasserman, M., "Recommendations for IPv6 in Third Generation		[6] Wasserman, M., "Recommendations for IPv6 in Third Generation
	Partnership Project (3GPP) Standards", RFC3314, September 2002.		Partnership Project (3GPP) Standards", RFC3314, September 2002.
	Editor's Address		9. Editor's Address
	Jonne Soininen		Jonne Soininen
	Nokia		Nokia
	313 Fairchild Dr. Phone: +1-650-864-6794		313 Fairchild Dr.
	Mountain View, CA, USA Email: jonne.soininen@nokia.com		Mountain View, CA, USA
			Phone: +1-650-864-6794
			EMail: jonne.soininen@nokia.com
			10. Full Copyright Statement
			Copyright (C) The Internet Society (2003). All Rights Reserved.
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			developing Internet standards in which case the procedures for
			copyrights defined in the Internet Standards process must be
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			The limited permissions granted above are perpetual and will not be
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			This document and the information contained herein is provided on an
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			Acknowledgement
			Funding for the RFC Editor function is currently provided by the
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