Internet Engineering Task Force (IETF) J. Korhonen, Ed.
Request for Comments: 6459 Nokia Siemens Networks
Category: Informational J. Soininen
ISSN: 2070-1721 Renesas Mobile
B. Patil
T. Savolainen
G. Bajko
Nokia
K. Iisakkila
Renesas Mobile
January 2012
Internet Engineering Task Force (IETF) J. Korhonen, Ed.
Request for Comments: 6459 Nokia Siemens Networks
Category: Informational J. Soininen
ISSN: 2070-1721 Renesas Mobile
B. Patil
T. Savolainen
G. Bajko
Nokia
K. Iisakkila
Renesas Mobile
January 2012
IPv6 in 3rd Generation Partnership Project (3GPP) Evolved Packet System (EPS)
第三代合作伙伴计划（3GPP）演进包系统（EPS）中的IPv6
Abstract
摘要
The use of cellular broadband for accessing the Internet and other data services via smartphones, tablets, and notebook/netbook computers has increased rapidly as a result of high-speed packet data networks such as HSPA, HSPA+, and now Long-Term Evolution (LTE) being deployed. Operators that have deployed networks based on 3rd Generation Partnership Project (3GPP) network architectures are facing IPv4 address shortages at the Internet registries and are feeling pressure to migrate to IPv6. This document describes the support for IPv6 in 3GPP network architectures.
由于HSPA、HSPA+等高速分组数据网络以及现在正在部署的长期演进（LTE），通过智能手机、平板电脑和笔记本/上网本计算机访问互联网和其他数据服务的蜂窝宽带的使用迅速增加。已部署基于第三代合作伙伴关系项目（3GPP）网络体系结构的网络的运营商在互联网注册处面临IPv4地址短缺的问题，并感受到迁移到IPv6的压力。本文档描述了3GPP网络体系结构中对IPv6的支持。
Status of This Memo
关于下段备忘
This document is not an Internet Standards Track specification; it is published for informational purposes.
本文件不是互联网标准跟踪规范；它是为了提供信息而发布的。
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 5741.
本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。并非IESG批准的所有文件都适用于任何级别的互联网标准；见RFC 5741第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc6459.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问http://www.rfc-editor.org/info/rfc6459.
Copyright Notice
版权公告
Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2012 IETF信托基金和确定为文件作者的人员。版权所有。
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Introduction ....................................................4
2. 3GPP Terminology and Concepts ...................................5
2.1. Terminology ................................................5
2.2. The Concept of APN ........................................10
3. IP over 3GPP GPRS ..............................................11
3.1. Introduction to 3GPP GPRS .................................11
3.2. PDP Context ...............................................12
4. IP over 3GPP EPS ...............................................13
4.1. Introduction to 3GPP EPS ..................................13
4.2. PDN Connection ............................................14
4.3. EPS Bearer Model ..........................................15
5. Address Management .............................................16
5.1. IPv4 Address Configuration ................................16
5.2. IPv6 Address Configuration ................................16
5.3. Prefix Delegation .........................................17
5.4. IPv6 Neighbor Discovery Considerations ....................18
6. 3GPP Dual-Stack Approach to IPv6 ...............................18
6.1. 3GPP Networks Prior to Release-8 ..........................18
6.2. 3GPP Release-8 and -9 Networks ............................20
6.3. PDN Connection Establishment Process ......................21
6.4. Mobility of 3GPP IPv4v6 Bearers ...........................23
7. Dual-Stack Approach to IPv6 Transition in 3GPP Networks ........24
8. Deployment Issues ..............................................25
8.1. Overlapping IPv4 Addresses ................................25
8.2. IPv6 for Transport ........................................26
8.3. Operational Aspects of Running Dual-Stack Networks ........26
8.4. Operational Aspects of Running a Network with
IPv6-Only Bearers .........................................27
8.5. Restricting Outbound IPv6 Roaming .........................28
8.6. Inter-RAT Handovers and IP Versions .......................29
8.7. Provisioning of IPv6 Subscribers and Various
Combinations during Initial Network Attachment ............29
9. Security Considerations ........................................31
10. Summary and Conclusions .......................................32
11. Acknowledgements ..............................................32
12. Informative References ........................................33
1. Introduction ....................................................4
2. 3GPP Terminology and Concepts ...................................5
2.1. Terminology ................................................5
2.2. The Concept of APN ........................................10
3. IP over 3GPP GPRS ..............................................11
3.1. Introduction to 3GPP GPRS .................................11
3.2. PDP Context ...............................................12
4. IP over 3GPP EPS ...............................................13
4.1. Introduction to 3GPP EPS ..................................13
4.2. PDN Connection ............................................14
4.3. EPS Bearer Model ..........................................15
5. Address Management .............................................16
5.1. IPv4 Address Configuration ................................16
5.2. IPv6 Address Configuration ................................16
5.3. Prefix Delegation .........................................17
5.4. IPv6 Neighbor Discovery Considerations ....................18
6. 3GPP Dual-Stack Approach to IPv6 ...............................18
6.1. 3GPP Networks Prior to Release-8 ..........................18
6.2. 3GPP Release-8 and -9 Networks ............................20
6.3. PDN Connection Establishment Process ......................21
6.4. Mobility of 3GPP IPv4v6 Bearers ...........................23
7. Dual-Stack Approach to IPv6 Transition in 3GPP Networks ........24
8. Deployment Issues ..............................................25
8.1. Overlapping IPv4 Addresses ................................25
8.2. IPv6 for Transport ........................................26
8.3. Operational Aspects of Running Dual-Stack Networks ........26
8.4. Operational Aspects of Running a Network with
IPv6-Only Bearers .........................................27
8.5. Restricting Outbound IPv6 Roaming .........................28
8.6. Inter-RAT Handovers and IP Versions .......................29
8.7. Provisioning of IPv6 Subscribers and Various
Combinations during Initial Network Attachment ............29
9. Security Considerations ........................................31
10. Summary and Conclusions .......................................32
11. Acknowledgements ..............................................32
12. Informative References ........................................33
IPv6 support has been part of the 3rd Generation Partnership Project (3GPP) standards since the first release of the specifications (Release 99). This support extends to all radio access and packet-based system variants of the 3GPP architecture family. In addition, a lot of work has been invested by the industry to investigate different transition and deployment scenarios over the years. However, IPv6 deployment in commercial networks remains low. There are many factors that can be attributed to this lack of deployment. The most relevant factor is essentially the same as the reason for IPv6 not being deployed in other networks either, i.e., the lack of business and commercial incentives for deployment.
自规范第一次发布（版本99）以来，IPv6支持一直是第三代合作伙伴关系项目（3GPP）标准的一部分。这种支持扩展到3GPP体系结构系列的所有无线接入和基于分组的系统变体。此外，多年来，业界投入了大量工作来调查不同的过渡和部署场景。然而，IPv6在商业网络中的部署仍然很低。有许多因素可归因于缺乏部署。最相关的因素本质上与IPv6未部署在其他网络中的原因相同，即部署缺乏商业和商业激励。
3GPP network architectures have continued to evolve in the time since Release 99, which was finalized in early 2000. The most recent version of the 3GPP architecture, the Evolved Packet System (EPS) -- commonly referred to as System Architecture Evolution (SAE), Long-Term Evolution (LTE), or Release-8 -- is a packet-centric architecture. In addition, the number of subscribers and devices using the 3GPP networks for Internet connectivity and data services has also increased phenomenally -- the number of mobile broadband subscribers has increased exponentially over the last couple of years.
3GPP网络架构自发布99（于2000年初最终确定）以来一直在不断发展。3GPP架构的最新版本，演进分组系统（EPS）——通常称为系统架构演进（SAE）、长期演进（LTE）或版本8——是以分组为中心的架构。此外，使用3GPP网络进行互联网连接和数据服务的用户和设备数量也显著增加——移动宽带用户数量在过去几年中呈指数级增长。
With subscriber growth projected to increase even further, and with recent depletion of available IPv4 address space by IANA, 3GPP operators and vendors are now in the process of identifying the scenarios and solutions needed to deploy IPv6.
随着订户增长预计将进一步增加，以及IANA最近耗尽了可用IPv4地址空间，3GPP运营商和供应商现在正在确定部署IPv6所需的场景和解决方案。
This document describes the establishment of IP connectivity in 3GPP network architectures, specifically in the context of IP bearers for 3G General Packet Radio Service (GPRS) and for EPS. It provides an overview of how IPv6 is supported as per the current set of 3GPP specifications. Some of the issues and concerns with respect to deployment and shortage of private IPv4 addresses within a single network domain are also discussed.
本文档描述了3GPP网络体系结构中IP连接的建立，特别是在3G通用分组无线业务（GPRS）和EPS的IP承载环境中。它概述了如何根据当前的3GPP规范支持IPv6。还讨论了在单个网络域中部署和缺少专用IPv4地址的一些问题和顾虑。
The IETF has specified a set of tools and mechanisms that can be utilized for transitioning to IPv6. In addition to operating dual-stack networks during the transition from IPv4 to IPv6, the two alternative categories for the transition are encapsulation and translation. The IETF continues to specify additional solutions for enabling the transition based on the deployment scenarios and
IETF指定了一组可用于过渡到IPv6的工具和机制。除了在从IPv4过渡到IPv6的过程中运行双栈网络外，过渡的两个可选类别是封装和转换。IETF继续根据部署场景和需求，为实现过渡指定其他解决方案
operator/ISP requirements. There is no single approach for transition to IPv6 that can meet the needs for all deployments and models. The 3GPP scenarios for transition, described in [TR.23975], can be addressed using transition mechanisms that are already available in the toolbox. The objective of transition to IPv6 in 3GPP networks is to ensure that:
运营商/ISP要求。没有一种过渡到IPv6的方法可以满足所有部署和型号的需要。[TR.23975]中描述的3GPP过渡场景可以使用工具箱中已有的过渡机制来解决。在3GPP网络中过渡到IPv6的目标是确保：
1. Legacy devices and hosts that have an IPv4-only stack will continue to be provided with IP connectivity to the Internet and services.
1. 具有仅IPv4协议栈的旧设备和主机将继续提供到Internet和服务的IP连接。
2. Devices that are dual-stack can access the Internet either via IPv6 or IPv4. The choice of using IPv6 or IPv4 depends on the capability of:
2. 双栈设备可以通过IPv6或IPv4访问Internet。使用IPv6或IPv4的选择取决于以下功能：
A. the application on the host,
A.主机上的应用程序，
B. the support for IPv4 and IPv6 bearers by the network, and/or
B.网络对IPv4和IPv6承载的支持，和/或
C. the server(s) and other end points.
C.服务器和其他端点。
3GPP networks are capable of providing a host with IPv4 and IPv6 connectivity today, albeit in many cases with upgrades to network elements such as the Serving GPRS Support Node (SGSN) and the Gateway GPRS Support Node (GGSN).
目前，3GPP网络能够为主机提供IPv4和IPv6连接，尽管在许多情况下需要升级网络元素，如服务GPRS支持节点（SGSN）和网关GPRS支持节点（GGSN）。
Access Point Name
接入点名称
The Access Point Name (APN) is a Fully Qualified Domain Name (FQDN) and resolves to a set of gateways in an operator's network. The APNs are piggybacked on the administration of the DNS namespace.
接入点名称（APN）是一个完全限定的域名（FQDN），可解析为运营商网络中的一组网关。APN依靠DNS名称空间的管理。
Dual Address PDN/PDP Type
双地址PDN/PDP类型
The dual address Packet Data Network/Packet Data Protocol (PDN/ PDP) Type (IPv4v6) is used in 3GPP context in many cases as a synonym for dual-stack, i.e., a connection type capable of serving both IPv4 and IPv6 simultaneously.
双地址分组数据网络/分组数据协议（PDN/PDP）类型（IPv4v6）在许多情况下在3GPP上下文中用作双栈的同义词，即，能够同时服务于IPv4和IPv6的连接类型。
Evolved Packet Core
进化包核
The Evolved Packet Core (EPC) is an evolution of the 3GPP GPRS system characterized by a higher-data-rate, lower-latency, packet-optimized system. The EPC comprises subcomponents such as the Mobility Management Entity (MME), Serving Gateway (SGW), Packet Data Network Gateway (PDN-GW), and Home Subscriber Server (HSS).
演进分组核心（EPC）是3GPP GPRS系统的演进，其特点是具有更高的数据速率、更低的延迟和分组优化系统。EPC包括子组件，例如移动性管理实体（MME）、服务网关（SGW）、分组数据网络网关（PDN-GW）和家庭用户服务器（HSS）。
Evolved Packet System
进化包系统
The Evolved Packet System (EPS) is an evolution of the 3GPP GPRS system characterized by a higher-data-rate, lower-latency, packet-optimized system that supports multiple Radio Access Technologies (RATs). The EPS comprises the EPC together with the Evolved Universal Terrestrial Radio Access (E-UTRA) and the Evolved Universal Terrestrial Radio Access Network (E-UTRAN).
演进分组系统（EPS）是3GPP GPRS系统的演进，其特点是具有更高的数据速率、更低的延迟、支持多种无线接入技术（RAT）的分组优化系统。EPS包括EPC以及演进的通用地面无线电接入（E-UTRA）和演进的通用地面无线电接入网络（E-UTRAN）。
Evolved UTRAN
进化乌特兰
The Evolved UTRAN (E-UTRAN) is a communications network, sometimes referred to as 4G, and consists of eNodeBs (4G base stations), which make up the E-UTRAN. The E-UTRAN allows connectivity between the User Equipment and the core network.
演进UTRAN（E-UTRAN）是通信网络，有时被称为4G，并且由enodeb（4G基站）组成，其构成E-UTRAN。E-UTRAN允许用户设备与核心网络之间的连接。
GPRS Tunnelling Protocol
GPRS隧道协议
The GPRS Tunnelling Protocol (GTP) [TS.29060] [TS.29274] [TS.29281] is a tunnelling protocol defined by 3GPP. It is a network-based mobility protocol and is similar to Proxy Mobile IPv6 (PMIPv6) [RFC5213]. However, GTP also provides functionality beyond mobility, such as in-band signaling related to Quality of Service (QoS) and charging, among others.
GPRS隧道协议（GTP）[TS.29060][TS.29274][TS.29281]是由3GPP定义的隧道协议。它是一种基于网络的移动协议，类似于代理移动IPv6（PMIPv6）[RFC5213]。然而，GTP还提供移动性以外的功能，例如与服务质量（QoS）和收费等相关的带内信令。
GSM EDGE Radio Access Network
GSM边缘无线接入网
The Global System for Mobile Communications (GSM) EDGE Radio Access Network (GERAN) is a communications network, commonly referred to as 2G or 2.5G, and consists of base stations and Base Station Controllers (BSCs), which make up the GSM EDGE radio access network. The GERAN allows connectivity between the User Equipment and the core network.
全球移动通信系统（GSM）边缘无线电接入网（GERAN）是一种通信网络，通常称为2G或2.5G，由基站和基站控制器（BSC）组成，它们构成GSM边缘无线电接入网。GERAN允许用户设备和核心网络之间的连接。
Gateway GPRS Support Node
网关GPRS支持节点
The Gateway GPRS Support Node (GGSN) is a gateway function in the GPRS that provides connectivity to the Internet or other PDNs. The host attaches to a GGSN identified by an APN assigned to it by an operator. The GGSN also serves as the topological anchor for addresses/prefixes assigned to the User Equipment.
网关GPRS支持节点（GGSN）是GPRS中的网关功能，可提供到Internet或其他PDN的连接。主机连接到由操作员分配给它的APN标识的GGSN。GGSN还充当分配给用户设备的地址/前缀的拓扑锚。
General Packet Radio Service
通用分组无线业务
The General Packet Radio Service (GPRS) is a packet-oriented mobile data service available to users of the 2G and 3G cellular communication systems -- the GSM -- specified by 3GPP.
通用分组无线业务（GPRS）是一种面向分组的移动数据业务，可供3GPP指定的2G和3G蜂窝通信系统（GSM）的用户使用。
High-Speed Packet Access
高速分组接入
The High-Speed Packet Access (HSPA) and HSPA+ are enhanced versions of the Wideband Code Division Multiple Access (WCDMA) and UTRAN, thus providing more data throughput and lower latencies.
高速分组接入（HSPA）和HSPA+是宽带码分多址（WCDMA）和UTRAN的增强版本，因此提供了更多的数据吞吐量和更低的延迟。
Home Location Register
本地位置寄存器
The Home Location Register (HLR) is a pre-Release-5 database (but is also used in Release-5 and later networks in real deployments) that contains subscriber data and information related to call routing. All subscribers of an operator, and the subscribers' enabled services, are provisioned in the HLR.
归属位置寄存器（HLR）是Release-5之前的数据库（但在实际部署中也用于Release-5和更高版本的网络），其中包含与呼叫路由相关的订户数据和信息。运营商的所有订户以及订户启用的服务都在HLR中提供。
Home Subscriber Server
家庭订户服务器
The Home Subscriber Server (HSS) is a database for a given subscriber and was introduced in 3GPP Release-5. It is the entity containing the subscription-related information to support the network entities actually handling calls/sessions.
归属订户服务器（HSS）是给定订户的数据库，在3GPP版本5中引入。它是包含订阅相关信息的实体，用于支持实际处理呼叫/会话的网络实体。
Mobility Management Entity
移动管理实体
The Mobility Management Entity (MME) is a network element that is responsible for control-plane functionalities, including authentication, authorization, bearer management, layer-2 mobility, etc. The MME is essentially the control-plane part of the SGSN in the GPRS. The user-plane traffic bypasses the MME.
移动管理实体（MME）是负责控制平面功能的网元，包括身份验证、授权、承载管理、第二层移动等。MME基本上是GPRS中SGSN的控制平面部分。用户平面业务绕过MME。
Mobile Terminal
移动终端
The Mobile Terminal (MT) is the modem and the radio part of the Mobile Station (MS).
移动终端（MT）是移动台（MS）的调制解调器和无线电部分。
Public Land Mobile Network
公共陆地移动网络
The Public Land Mobile Network (PLMN) is a network that is operated by a single administration. A PLMN (and therefore also an operator) is identified by the Mobile Country Code (MCC) and the Mobile Network Code (MNC). Each (telecommunications) operator providing mobile services has its own PLMN.
公共陆地移动网络（PLMN）是由单一管理机构运营的网络。PLMN（因此也是运营商）由移动国家代码（MCC）和移动网络代码（MNC）标识。提供移动服务的每个（电信）运营商都有自己的PLMN。
Policy and Charging Control
政策及收费管制
The Policy and Charging Control (PCC) framework is used for QoS policy and charging control. It has two main functions: flow-based charging, including online credit control; and policy control (e.g., gating control, QoS control, and QoS signaling). It is optional to 3GPP EPS but needed if dynamic policy and charging control by means of PCC rules based on user and services are desired.
策略和计费控制（PCC）框架用于QoS策略和计费控制。它有两个主要功能：基于流量的收费，包括在线信用控制；和策略控制（例如，选通控制、QoS控制和QoS信令）。它对于3GPP EPS是可选的，但如果需要基于用户和服务的动态策略和通过PCC规则进行的收费控制，则需要它。
Packet Data Network
分组数据网络
The Packet Data Network (PDN) is a packet-based network that either belongs to the operator or is an external network such as the Internet or a corporate intranet. The user eventually accesses services in one or more PDNs. The operator's packet core networks are separated from packet data networks either by GGSNs or PDN Gateways (PDN-GWs).
分组数据网络（PDN）是基于分组的网络，属于运营商或是外部网络，例如因特网或公司内部网。用户最终访问一个或多个PDN中的服务。运营商的分组核心网络通过GGSNs或PDN网关（PDN GWs）与分组数据网络分离。
Packet Data Network Gateway
分组数据网络网关
The Packet Data Network Gateway (PDN-GW) is a gateway function in the Evolved Packet System (EPS), which provides connectivity to the Internet or other PDNs. The host attaches to a PDN-GW identified by an APN assigned to it by an operator. The PDN-GW also serves as the topological anchor for addresses/prefixes assigned to the User Equipment.
分组数据网络网关（PDN-GW）是演进分组系统（EPS）中的网关功能，它提供到Internet或其他PDN的连接。主机连接到由操作员分配给它的APN标识的PDN-GW。PDN-GW还充当分配给用户设备的地址/前缀的拓扑锚。
Packet Data Protocol Context
分组数据协议上下文
A Packet Data Protocol (PDP) context is the equivalent of a virtual connection between the User Equipment (UE) and a PDN using a specific gateway.
分组数据协议（PDP）上下文相当于用户设备（UE）和使用特定网关的PDN之间的虚拟连接。
Packet Data Protocol Type
分组数据协议类型
A Packet Data Protocol Type (PDP Type) identifies the used/allowed protocols within the PDP context. Examples are IPv4, IPv6, and IPv4v6 (dual-stack).
分组数据协议类型（PDP类型）标识PDP上下文中使用/允许的协议。例如IPv4、IPv6和IPv4v6（双堆栈）。
S4 Serving GPRS Support Node
S4服务GPRS支持节点
The S4 Serving GPRS Support Node (S4-SGSN) is compliant with a Release-8 (and onwards) SGSN that connects 2G/3G radio access networks to the EPC via new Release-8 interfaces like S3, S4, and S6d.
服务于S4的GPRS支持节点（S4-SGSN）符合第8版（及更高版本）的SGSN，该SGSN通过新的第8版接口（如S3、S4和S6d）将2G/3G无线接入网络连接到EPC。
Serving Gateway
服务网关
The Serving Gateway (SGW) is a gateway function in the EPS, which terminates the interface towards the E-UTRAN. The SGW is the Mobility Anchor point for layer-2 mobility (inter-eNodeB handovers). For each UE connected with the EPS, at any given point in time, there is only one SGW. The SGW is essentially the user-plane part of the GPRS's SGSN.
服务网关（SGW）是EPS中的网关功能，其终止朝向E-UTRAN的接口。SGW是第2层移动性（eNodeB间切换）的移动性锚点。对于与EPS连接的每个UE，在任何给定的时间点，只有一个SGW。SGW本质上是GPRS的SGSN的用户平面部分。
Serving GPRS Support Node
服务GPRS支持节点
The Serving GPRS Support Node (SGSN) is a network element that is located between the radio access network (RAN) and the gateway (GGSN). A per-UE point-to-point (p2p) tunnel between the GGSN and SGSN transports the packets between the UE and the gateway.
服务GPRS支持节点（SGSN）是位于无线接入网络（RAN）和网关（GGSN）之间的网元。GGSN和SGSN之间的每UE点对点（p2p）隧道在UE和网关之间传输分组。
Terminal Equipment
终端设备
The Terminal Equipment (TE) is any device/host connected to the Mobile Terminal (MT) offering services to the user. A TE may communicate to an MT, for example, over the Point to Point Protocol (PPP).
终端设备（TE）是连接到向用户提供服务的移动终端（MT）的任何设备/主机。TE可以例如通过点对点协议（PPP）与MT通信。
UE, MS, MN, and Mobile
UE、MS、MN和移动设备
The terms UE (User Equipment), MS (Mobile Station), MN (Mobile Node), and mobile refer to the devices that are hosts with the ability to obtain Internet connectivity via a 3GPP network. A MS is comprised of the Terminal Equipment (TE) and a Mobile Terminal (MT). The terms UE, MS, MN, and mobile are used interchangeably within this document.
术语UE（用户设备）、MS（移动站）、MN（移动节点）和移动设备指的是作为能够经由3GPP网络获得因特网连接的主机的设备。MS由终端设备（TE）和移动终端（MT）组成。术语UE、MS、MN和mobile在本文档中互换使用。
UMTS Terrestrial Radio Access Network
陆地无线接入网
The Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (UTRAN) is a communications network, commonly referred to as 3G, and consists of NodeBs (3G base stations) and Radio Network Controllers (RNCs), which make up the UMTS radio access network. The UTRAN allows connectivity between the UE and the core network. The UTRAN is comprised of WCDMA, HSPA, and HSPA+ radio technologies.
通用移动通信系统（UMTS）地面无线接入网（UTRAN）是一种通信网络，通常被称为3G，由节点B（3G基站）和无线网络控制器（RNC）组成，它们构成了UMTS无线接入网。UTRAN允许UE和核心网络之间的连接。UTRAN由WCDMA、HSPA和HSPA+无线电技术组成。
User Plane
用户平面
The user plane refers to data traffic and the required bearers for the data traffic. In practice, IP is the only data traffic protocol used in the user plane.
用户平面指的是数据业务和数据业务所需的承载。实际上，IP是用户平面中使用的唯一数据通信协议。
Wideband Code Division Multiple Access
宽带码分多址
The Wideband Code Division Multiple Access (WCDMA) is the radio interface used in UMTS networks.
宽带码分多址（WCDMA）是UMTS网络中使用的无线电接口。
eNodeB
基站
The eNodeB is a base station entity that supports the Long-Term Evolution (LTE) air interface.
eNodeB是支持长期演进（LTE）空中接口的基站实体。
The Access Point Name (APN) essentially refers to a gateway in the 3GPP network. The 'complete' APN is expressed in a form of a Fully Qualified Domain Name (FQDN) and also piggybacked on the administration of the DNS namespace, thus effectively allowing the discovery of gateways using the DNS. The UE can choose to attach to a specific gateway in the packet core. The gateway provides connectivity to the Packet Data Network (PDN), such as the Internet. An operator may also include gateways that do not provide Internet connectivity but rather provide connectivity to a closed network providing a set of the operator's own services. A UE can be attached to one or more gateways simultaneously. The gateway in a 3GPP network is the GGSN or PDN-GW. Figure 1 illustrates the APN-based network connectivity concept.
接入点名称（APN）基本上是指3GPP网络中的网关。“完整”APN以完全限定的域名（FQDN）的形式表示，并且还依赖于DNS命名空间的管理，因此有效地允许使用DNS发现网关。UE可以选择连接到分组核心中的特定网关。网关提供与分组数据网络（PDN）的连接，如互联网。运营商还可以包括不提供互联网连接而是提供到提供运营商自己的一组服务的封闭网络的连接的网关。UE可以同时连接到一个或多个网关。3GPP网络中的网关是GGSN或PDN-GW。图1说明了基于APN的网络连接概念。
.--.
_(. `)
.--. +------------+ _( PDN `)_
_(Core`. |GW1 |====( Internet `)
+---+ ( NW )------|APN=internet| ( ` . ) )
[UE]~~~~|RAN|----( ` . ) )--+ +------------+ `--(_______)---'
^ +---+ `--(___.-' |
| | .--.
| | +----------+ _(.PDN`)
| +--|GW2 | _(Operator`)_
| |APN=OpServ|====( Services `)
UE is attached +----------+ ( ` . ) )
to GW1 and GW2 `--(_______)---'
simultaneously
.--.
_(. `)
.--. +------------+ _( PDN `)_
_(Core`. |GW1 |====( Internet `)
+---+ ( NW )------|APN=internet| ( ` . ) )
[UE]~~~~|RAN|----( ` . ) )--+ +------------+ `--(_______)---'
^ +---+ `--(___.-' |
| | .--.
| | +----------+ _(.PDN`)
| +--|GW2 | _(Operator`)_
| |APN=OpServ|====( Services `)
UE is attached +----------+ ( ` . ) )
to GW1 and GW2 `--(_______)---'
simultaneously
Figure 1: User Equipment Attached to Multiple APNs Simultaneously
图1：同时连接到多个APN的用户设备
A simplified 2G/3G GPRS architecture is illustrated in Figure 2. This architecture basically covers the GPRS core network from R99 to Release-7, and radio access technologies such as GSM (2G), EDGE (2G, often referred to as 2.5G), WCDMA (3G), and HSPA(+) (3G, often referred to as 3.5G). The architecture shares obvious similarities with the Evolved Packet System (EPS), as will be seen in Section 4. Based on Gn/Gp interfaces, the GPRS core network functionality is logically implemented on two network nodes -- the SGSN and the GGSN.
简化的2G/3G GPRS架构如图2所示。该架构基本上涵盖了从R99到Release-7的GPRS核心网络，以及GSM（2G）、EDGE（2G，通常称为2.5G）、WCDMA（3G）和HSPA（+）（3G，通常称为3.5G）等无线接入技术。该体系结构与进化包系统（EPS）有明显的相似性，如第4节所示。基于Gn/Gp接口，GPRS核心网络功能在两个网络节点——SGSN和GGSN上逻辑实现。
3G
.--. .--.
Uu _( `. Iu +----+ +----+ _( `.
[UE]~~|~~~( UTRAN )--|---|SGSN|--|---|GGSN|--|----( PDN )
( ` . ) ) +----+ Gn +----+ Gi ( ` . ) )
`--(___.-' / | `--(___.-'
/ |
2G Gb-- |
.--. / |
_( `. / --Gp
[UE]~~|~~~( PDN )__/ |
Um ( ` . ) ) .--.
`--(___.-' _(. `)
_( [GGSN] `)_
( other `)
( ` . PLMN ) )
`--(_______)---'
3G
.--. .--.
Uu _( `. Iu +----+ +----+ _( `.
[UE]~~|~~~( UTRAN )--|---|SGSN|--|---|GGSN|--|----( PDN )
( ` . ) ) +----+ Gn +----+ Gi ( ` . ) )
`--(___.-' / | `--(___.-'
/ |
2G Gb-- |
.--. / |
_( `. / --Gp
[UE]~~|~~~( PDN )__/ |
Um ( ` . ) ) .--.
`--(___.-' _(. `)
_( [GGSN] `)_
( other `)
( ` . PLMN ) )
`--(_______)---'
Figure 2: Overview of the 2G/3G GPRS Logical Architecture
图2:2G/3G GPRS逻辑架构概述
Gn/Gp: Interfaces that provide a network-based mobility service for a UE and are used between an SGSN and a GGSN. The Gn interface is used when the GGSN and SGSN are located inside one operator (i.e., a PLMN). The Gp-interface is used if the GGSN and the SGSN are located in different operator domains (i.e., a different PLMN). GTP is defined for the Gn/Gp interfaces (both GTP-C for the control plane and GTP-U for the user plane).
Gn/Gp：为UE提供基于网络的移动服务并在SGSN和GGSN之间使用的接口。当GGSN和SGSN位于一个运营商（即PLMN）内部时，使用Gn接口。如果GGSN和SGSN位于不同的运营商域（即，不同的PLMN），则使用Gp接口。GTP是为Gn/Gp接口定义的（GTP-C用于控制平面，GTP-U用于用户平面）。
Gb: The Base Station System (BSS)-to-SGSN interface, which is used to carry information concerning packet data transmission and layer-2 mobility management. The Gb-interface is based on either Frame Relay or IP.
Gb：基站系统（BSS）-到SGSN的接口，用于承载有关分组数据传输和第二层移动性管理的信息。Gb接口基于帧中继或IP。
Iu: The Radio Network System (RNS)-to-SGSN interface, which is used to carry information concerning packet data transmission and layer-2 mobility management. The user-plane part of the Iu-interface (actually the Iu-PS) is based on GTP-U. The control-plane part of the Iu-interface is based on the Radio Access Network Application Protocol (RANAP).
Iu：无线网络系统（RNS）-到SGSN的接口，用于承载有关分组数据传输和第二层移动性管理的信息。Iu接口的用户平面部分（实际上是Iu PS）基于GTP-U。Iu接口的控制平面部分基于无线接入网络应用协议（RANAP）。
Gi: The interface between the GGSN and a PDN. The PDN may be an operator's external public or private packet data network, or an intra-operator packet data network.
Gi：GGSN和PDN之间的接口。PDN可以是运营商的外部公共或私有分组数据网络，或者是运营商内部分组数据网络。
Uu/Um: 2G or 3G radio interfaces between a UE and a respective radio access network.
Uu/Um:UE和相应无线接入网络之间的2G或3G无线接口。
The SGSN is responsible for the delivery of data packets from and to the UE within its geographical service area when a direct tunnel option is not used. If the direct tunnel is used, then the user plane goes directly between the RNC (in the RNS) and the GGSN. The control-plane traffic always goes through the SGSN. For each UE connected with the GPRS, at any given point in time, there is only one SGSN.
当不使用直接隧道选项时，SGSN负责在其地理服务区域内从UE和向UE递送数据分组。如果使用直接隧道，则用户平面直接位于RNC（在RNS中）和GGSN之间。控制飞机流量始终通过SGSN。对于与GPRS连接的每个UE，在任何给定的时间点，只有一个SGSN。
A PDP (Packet Data Protocol) context is an association between a UE represented by one IPv4 address and/or one /64 IPv6 prefix, and a PDN represented by an APN. Each PDN can be accessed via a gateway (typically a GGSN or PDN-GW). On the UE, a PDP context is equivalent to a network interface. A UE may hence be attached to one or more gateways via separate connections, i.e., PDP contexts. 3GPP GPRS supports PDP Types IPv4, IPv6, and since Release-9, PDP Type IPv4v6 (dual-stack) as well.
PDP（分组数据协议）上下文是由一个IPv4地址和/或一个/64 IPv6前缀表示的UE与由APN表示的PDN之间的关联。可以通过网关（通常是GGSN或PDN-GW）访问每个PDN。在UE上，PDP上下文相当于网络接口。因此，UE可以经由单独的连接（即，PDP上下文）连接到一个或多个网关。3GPP GPRS支持PDP类型IPv4、IPv6以及自发布9以来的PDP类型IPv4v6（双栈）。
Each primary PDP context has its own IPv4 address and/or one /64 IPv6 prefix assigned to it by the PDN and anchored in the corresponding gateway. The GGSN or PDN-GW is the first-hop router for the UE. Applications on the UE use the appropriate network interface (PDP context) for connectivity to a specific PDN. Figure 3 represents a high-level view of what a PDP context implies in 3GPP networks.
每个主PDP上下文都有自己的IPv4地址和/或PDN分配给它的一个/64 IPv6前缀，并锚定在相应的网关中。GGSN或PDN-GW是UE的第一跳路由器。UE上的应用程序使用适当的网络接口（PDP上下文）来连接到特定PDN。图3显示了3GPP网络中PDP上下文含义的高级视图。
Y
| +---------+ .--.
|--+ __________________________ | APNx in | _( `.
| |O______PDPc1_______________)| GGSN / |----(Internet)
| | | PDN-GW | ( ` . ) )
|UE| +---------+ `--(___.-'
| | _______________________ +---------+ .--.
| |O______PDPc2____________)| APNy in | _(Priv`.
+--+ | GGSN / |-------(Network )
| PDN-GW | ( ` . ) )
+---------+ `--(___.-'
Y
| +---------+ .--.
|--+ __________________________ | APNx in | _( `.
| |O______PDPc1_______________)| GGSN / |----(Internet)
| | | PDN-GW | ( ` . ) )
|UE| +---------+ `--(___.-'
| | _______________________ +---------+ .--.
| |O______PDPc2____________)| APNy in | _(Priv`.
+--+ | GGSN / |-------(Network )
| PDN-GW | ( ` . ) )
+---------+ `--(___.-'
Figure 3: PDP Contexts between the MS/UE and Gateway
图3:MS/UE和网关之间的PDP上下文
In the above figure, there are two PDP contexts at the MS/UE: the 'PDPc1' PDP context, which is connected to APNx, provides Internet connectivity, and the 'PDPc2' PDP context provides connectivity to a private IP network via APNy (as an example, this network may include operator-specific services, such as the MMS (Multimedia Messaging Service)). An application on the host, such as a web browser, would use the PDP context that provides Internet connectivity for accessing services on the Internet. An application such as a MMS would use APNy in the figure above, because the service is provided through the private network.
在上图中，MS/UE处存在两个PDP上下文：“PDPc1”PDP上下文（连接到APNx）提供互联网连接，“PDPc2”PDP上下文通过APNy提供到私有IP网络的连接（例如，该网络可以包括特定于运营商的服务，例如MMS（多媒体消息服务））。主机上的应用程序（如web浏览器）将使用PDP上下文，该上下文提供Internet连接以访问Internet上的服务。MMS等应用程序将使用上图中的APNy，因为服务是通过专用网络提供的。
In its most basic form, the EPS architecture consists of only two nodes on the user plane: a base station and a core network Gateway (GW). The basic EPS architecture is illustrated in Figure 4. The functional split of gateways allows operators to choose optimized topological locations of nodes within the network and enables various deployment models, including the sharing of radio networks between different operators. This also allows independent scaling, growth of traffic throughput, and control-signal processing.
在其最基本的形式中，EPS架构仅由用户平面上的两个节点组成：一个基站和一个核心网络网关（GW）。基本的EPS架构如图4所示。网关的功能划分允许运营商选择网络内节点的优化拓扑位置，并支持各种部署模型，包括不同运营商之间的无线网络共享。这还允许独立扩展、流量增长和控制信号处理。
+--------+
| IP |
S1-MME +-------+ S11 |Services|
+----|----| MME |----|----+ +--------+
| | | | |SGi
| +-------+ | S5/ |
+----+ LTE-Uu +-------+ S1-U +-------+ S8 +-------+
|UE |----|---|eNodeB |---|-----------------| SGW |--|---|PDN-GW |
| |========|=======|=====================|=======|======| |
+----+ +-------+Dual-Stack EPS Bearer+-------+ +-------+
+--------+
| IP |
S1-MME +-------+ S11 |Services|
+----|----| MME |----|----+ +--------+
| | | | |SGi
| +-------+ | S5/ |
+----+ LTE-Uu +-------+ S1-U +-------+ S8 +-------+
|UE |----|---|eNodeB |---|-----------------| SGW |--|---|PDN-GW |
| |========|=======|=====================|=======|======| |
+----+ +-------+Dual-Stack EPS Bearer+-------+ +-------+
Figure 4: EPS Architecture for 3GPP Access
图4:3GPP接入的EPS架构
S5/S8: Provides user-plane tunnelling and tunnel management between the SGW and PDN-GW, using GTP (both GTP-U and GTP-C) or PMIPv6 [RFC5213] [TS.23402] as the network-based mobility management protocol. The S5 interface is used when the PDN-GW and SGW are located inside one operator (i.e., a PLMN). The S8-interface is used if the PDN-GW and the SGW are located in different operator domains (i.e., a different PLMN).
S5/S8：使用GTP（GTP-U和GTP-C）或PMIPv6[RFC5213][TS.23402]作为基于网络的移动性管理协议，在SGW和PDN-GW之间提供用户平面隧道和隧道管理。当PDN-GW和SGW位于一个操作员（即PLMN）内时，使用S5接口。如果PDN-GW和SGW位于不同的运营商域（即，不同的PLMN），则使用S8接口。
S11: Reference point for the control-plane protocol between the MME and SGW, based on GTP-C (GTP control plane) and used, for example, during the establishment or modification of the default bearer.
S11：MME和SGW之间的控制平面协议的参考点，基于GTP-C（GTP控制平面），例如在默认承载的建立或修改期间使用。
S1-U: Provides user-plane tunnelling and inter-eNodeB path switching during handover between the eNodeB and SGW, using GTP-U (GTP user plane).
S1-U：使用GTP-U（GTP用户平面），在eNodeB和SGW之间的切换期间提供用户平面隧道和eNodeB间路径切换。
S1-MME: Reference point for the control-plane protocol between the eNodeB and MME.
S1-MME：eNodeB和MME之间控制平面协议的参考点。
SGi: The interface between the PDN-GW and the PDN. The PDN may be an operator-external public or private packet data network or an intra-operator packet data network.
SGi：PDN-GW和PDN之间的接口。PDN可以是运营商外部公共或私有分组数据网络或运营商内部分组数据网络。
A PDN connection is an association between a UE represented by one IPv4 address and/or one /64 IPv6 prefix, and a PDN represented by an APN. The PDN connection is the EPC equivalent of the GPRS PDP context. Each PDN can be accessed via a gateway (a PDN-GW). The PDN is responsible for the IP address/prefix allocation to the UE. On the UE, a PDN connection is equivalent to a network interface. A UE may hence be attached to one or more gateways via separate
PDN连接是由一个IPv4地址和/或一个/64 IPv6前缀表示的UE与由APN表示的PDN之间的关联。PDN连接等同于GPRS PDP上下文。每个PDN都可以通过网关（PDN-GW）访问。PDN负责向UE分配IP地址/前缀。在UE上，PDN连接相当于网络接口。因此，UE可以经由单独的网关连接到一个或多个网关
connections, i.e., PDN connections. 3GPP EPS supports PDN Types IPv4, IPv6, and IPv4v6 (dual-stack) since the beginning of EPS, i.e., since Release-8.
连接，即PDN连接。3GPP EPS从EPS开始，即从Release-8开始，就支持PDN类型IPv4、IPv6和IPv4v6（双栈）。
Each PDN connection has its own IP address/prefix assigned to it by the PDN and anchored in the corresponding gateway. In the case of the GTP-based S5/S8 interface, the PDN-GW is the first-hop router for the UE, and in the case of PMIPv6-based S5/S8, the SGW is the first-hop router. Applications on the UE use the appropriate network interface (PDN connection) for connectivity.
每个PDN连接都有自己的IP地址/前缀，由PDN分配给它，并锚定在相应的网关中。在基于GTP的S5/S8接口的情况下，PDN-GW是UE的第一跳路由器，并且在基于PMIPv6的S5/S8的情况下，SGW是第一跳路由器。UE上的应用程序使用适当的网络接口（PDN连接）进行连接。
The logical concept of a bearer has been defined to be an aggregate of one or more IP flows related to one or more services. An EPS bearer exists between the UE and the PDN-GW and is used to provide the same level of packet-forwarding treatment to the aggregated IP flows constituting the bearer. Services with IP flows requiring different packet-forwarding treatment would therefore require more than one EPS bearer. The UE performs the binding of the uplink IP flows to the bearer, while the PDN-GW performs this function for the downlink packets.
承载的逻辑概念被定义为与一个或多个服务相关的一个或多个IP流的集合。EPS承载存在于UE和PDN-GW之间，并且用于向构成该承载的聚合IP流提供相同级别的分组转发处理。因此，具有需要不同分组转发处理的IP流的服务将需要多个EPS承载。UE执行上行链路IP流到承载的绑定，而PDN-GW对下行链路分组执行该功能。
In order to always provide low latency on connectivity, a default bearer will be provided at the time of startup, and an IPv4 address and/or IPv6 prefix gets assigned to the UE (this is different from GPRS, where UEs are not automatically connected to a PDN and therefore do not get an IPv4 address and/or IPv6 prefix assigned until they activate their first PDP context). This default bearer will be allowed to carry all traffic that is not associated with a dedicated bearer. Dedicated bearers are used to carry traffic for IP flows that have been identified to require specific packet-forwarding treatment. They may be established at the time of startup -- for example, in the case of services that require always-on connectivity and better QoS than that provided by the default bearer. The default bearer and the dedicated bearer(s) associated to it share the same IP address(es)/prefix.
为了始终提供低连接延迟，将在启动时提供默认承载，并将IPv4地址和/或IPv6前缀分配给UE（这与GPRS不同，在GPRS中，UE不会自动连接到PDN，因此在激活其第一个PDP上下文之前不会获得分配的IPv4地址和/或IPv6前缀）。将允许此默认承载承载与专用承载无关的所有流量。专用承载用于承载已识别为需要特定数据包转发处理的IP流的流量。它们可以在启动时建立，例如，在需要始终打开的服务的情况下连接和QoS比默认承载提供的更好。默认承载和与其关联的专用承载共享相同的IP地址/前缀。
An EPS bearer is referred to as a Guaranteed Bit Rate (GBR) bearer if dedicated network resources related to a GBR value that is associated with the EPS bearer are permanently allocated (e.g., by an admission control function in the eNodeB) at bearer establishment/modification. Otherwise, an EPS bearer is referred to as a non-GBR bearer. The default bearer is always non-GBR, with the resources for the IP flows not guaranteed at the eNodeB, and with no admission control. However, the dedicated bearer can be either GBR or non-GBR. A GBR bearer has a GBR and Maximum Bit Rate (MBR), while more than one non-GBR bearer belonging to the same UE shares an Aggregate MBR
如果与与EPS承载相关联的GBR值相关的专用网络资源在承载建立/修改时被永久分配（例如，通过eNodeB中的接纳控制功能），则EPS承载被称为保证比特率（GBR）承载。否则，EPS承载称为非GBR承载。默认承载始终是非GBR的，在eNodeB上不保证IP流的资源，并且没有准入控制。然而，专用承载可以是GBR或非GBR。GBR承载具有GBR和最大比特率（MBR），而属于同一UE的多个非GBR承载共享聚合MBR
(AMBR). Non-GBR bearers can suffer packet loss under congestion, while GBR bearers are immune to such losses as long as they honor the contracted bit rates.
（AMBR）。非GBR承载在拥塞情况下会遭受数据包丢失，而GBR承载只要遵守约定的比特率，就不会受到此类丢失的影响。
The UE's IPv4 address configuration is always performed during PDP context/EPS bearer setup procedures (on layer 2). DHCPv4-based [RFC2131] address configuration is supported by the 3GPP specifications, but is not used on a wide scale. The UE must always support address configuration as part of the bearer setup signaling, since DHCPv4 is optional for both UEs and networks.
UE的IPv4地址配置始终在PDP上下文/EPS承载设置过程中执行（在第2层上）。3GPP规范支持基于DHCPv4的[RFC2131]地址配置，但未广泛使用。UE必须始终支持地址配置作为承载设置信令的一部分，因为DHCPv4对于UE和网络都是可选的。
The 3GPP standards also specify a 'deferred IPv4 address allocation' on a PMIPv6-based dual-stack IPv4v6 PDN connection at the time of connection establishment, as described in Section 4.7.1 of [TS.23402]. This has the advantage of a single PDN connection for IPv6 and IPv4, along with deferring IPv4 address allocation until an application needs it. The deferred address allocation is based on the use of DHCPv4 as well as appropriate UE-side implementation-dependent triggers to invoke the protocol.
3GPP标准还规定了在建立连接时基于PMIPv6的双栈IPv4v6 PDN连接上的“延迟IPv4地址分配”，如[TS.23402]第4.7.1节所述。这具有IPv6和IPv4的单个PDN连接的优势，同时将IPv4地址分配推迟到应用程序需要时。延迟地址分配基于使用DHCPv4以及适当的UE端实现相关触发器来调用协议。
IPv6 Stateless Address Autoconfiguration (SLAAC), as specified in [RFC4861] and [RFC4862], is the only supported address configuration mechanism. Stateful DHCPv6-based address configuration [RFC3315] is not supported by 3GPP specifications. On the other hand, stateless DHCPv6 service to obtain other configuration information is supported [RFC3736]. This implies that the M-bit is always zero and that the O-bit may be set to one in the Router Advertisement (RA) sent to the UE.
[RFC4861]和[RFC4862]中指定的IPv6无状态地址自动配置（SLAAC）是唯一受支持的地址配置机制。3GPP规范不支持基于状态DHCPv6的地址配置[RFC3315]。另一方面，支持获取其他配置信息的无状态DHCPv6服务[RFC3736]。这意味着M位始终为零，并且在发送到UE的路由器广告（RA）中，O位可以设置为1。
The 3GPP network allocates each default bearer a unique /64 prefix, and uses layer-2 signaling to suggest to the UE an Interface Identifier that is guaranteed not to conflict with the gateway's Interface Identifier. The UE must configure its link-local address using this Interface Identifier. The UE is allowed to use any Interface Identifier it wishes for the other addresses it configures. There is no restriction, for example, on using privacy extensions for SLAAC [RFC4941] or other similar types of mechanisms. However, there are network drivers that fail to pass the Interface Identifier to the stack and instead synthesize their own Interface Identifier (usually a Media Access Control (MAC) address equivalent). If the UE skips the Duplicate Address Detection (DAD) and also has other issues with the Neighbor Discovery protocol (see Section 5.4), then there is a
3GPP网络为每个默认承载分配唯一/64前缀，并使用第2层信令向UE建议保证不与网关的接口标识符冲突的接口标识符。UE必须使用此接口标识符配置其链路本地地址。允许UE对其配置的其他地址使用其希望的任何接口标识符。例如，对SLAAC[RFC4941]或其他类似类型的机制使用隐私扩展没有任何限制。但是，有些网络驱动程序无法将接口标识符传递给堆栈，而是合成自己的接口标识符（通常是媒体访问控制（MAC）地址等效物）。如果UE跳过重复地址检测（DAD），并且邻居发现协议也存在其他问题（参见第5.4节），则存在
small theoretical chance that the UE will configure exactly the same link-local address as the GGSN/PDN-GW. The address collision may then cause issues in IP connectivity -- for instance, the UE not being able to forward any packets to the uplink.
UE将配置与GGSN/PDN-GW完全相同的链路本地地址的理论可能性很小。然后，地址冲突可能会导致IP连接出现问题——例如，UE无法将任何数据包转发到上行链路。
In the 3GPP link model, the /64 prefix assigned to the UE cannot be used for on-link determination (because the L-bit in the Prefix Information Option (PIO) in the RA must always be set to zero). If the advertised prefix is used for SLAAC, then the A-bit in the PIO must be set to one. Details of the 3GPP link-model and address configuration are provided in Section 11.2.1.3.2a of [TS.29061]. More specifically, the GGSN/PDN-GW guarantees that the /64 prefix is unique for the UE. Therefore, there is no need to perform any DAD on addresses the UE creates (i.e., the 'DupAddrDetectTransmits' variable in the UE could be zero). The GGSN/PDN-GW is not allowed to generate any globally unique IPv6 addresses for itself using the /64 prefix assigned to the UE in the RA.
在3GPP链路模型中，分配给UE的/64前缀不能用于链路上确定（因为RA中的前缀信息选项（PIO）中的L位必须始终设置为零）。如果播发前缀用于SLAAC，则PIO中的A位必须设置为1。[TS.29061]第11.2.1.3.2a节提供了3GPP链路型号和地址配置的详细信息。更具体地说，GGSN/PDN-GW保证/64前缀对于UE是唯一的。因此，不需要对UE创建的地址执行任何DAD（即，UE中的“DupAddrDetectTransmists”变量可以为零）。不允许GGSN/PDN-GW使用分配给RA中的UE的/64前缀为自己生成任何全局唯一的IPv6地址。
The current 3GPP architecture limits the number of prefixes in each bearer to a single /64 prefix. If the UE finds more than one prefix in the RA, it only considers the first one and silently discards the others [TS.29061]. Therefore, multi-homing within a single bearer is not possible. Renumbering without closing the layer-2 connection is also not possible. The lifetime of the /64 prefix is bound to the lifetime of the layer-2 connection even if the advertised prefix lifetime is longer than the layer-2 connection lifetime.
当前3GPP架构将每个承载中的前缀数量限制为单个/64前缀。如果UE在RA中找到多个前缀，则它只考虑第一个前缀，并默默地丢弃其他前缀[TS.29061]。因此，不可能在单个承载内实现多主。在不关闭第2层连接的情况下重新编号也是不可能的。/64前缀的生存期绑定到第二层连接的生存期，即使播发的前缀生存期长于第二层连接的生存期。
IPv6 prefix delegation is a part of Release-10 and is not covered by any earlier releases. However, the /64 prefix allocated for each default bearer (and to the UE) may be shared to the local area network by the UE implementing Neighbor Discovery proxy (ND proxy) [RFC4389] functionality.
IPv6前缀委派是Release-10的一部分，任何早期版本都不包括。然而，为每个默认承载（和UE）分配的/64前缀可以由实现邻居发现代理（ND-proxy）[RFC4389]功能的UE共享到局域网。
The Release-10 prefix delegation uses the DHCPv6-based prefix delegation [RFC3633]. The model defined for Release-10 requires aggregatable prefixes, which means the /64 prefix allocated for the default bearer (and to the UE) must be part of the shorter delegated prefix. DHCPv6 prefix delegation has an explicit limitation, described in Section 12.1 of [RFC3633], that a prefix delegated to a requesting router cannot be used by the delegating router (i.e., the PDN-GW in this case). This implies that the shorter 'delegated prefix' cannot be given to the requesting router (i.e., the UE) as such but has to be delivered by the delegating router (i.e., the PDN-GW) in such a way that the /64 prefix allocated to the default bearer is not part of the 'delegated prefix'. An option to exclude a prefix from delegation [PD-EXCLUDE] prevents this problem.
Release-10前缀委派使用基于DHCPv6的前缀委派[RFC3633]。为Release-10定义的模型需要可聚合前缀，这意味着分配给默认承载（和UE）的/64前缀必须是较短的委托前缀的一部分。DHCPv6前缀委派有一个明确的限制，如[RFC3633]第12.1节所述，即委派路由器（即本例中的PDN-GW）不能使用委派给请求路由器的前缀。这意味着不能将较短的“委派前缀”给予请求路由器（即，UE），而是必须由委派路由器（即，PDN-GW）以这样的方式递送，即分配给默认承载的/64前缀不是“委派前缀”的一部分。从委派中排除前缀的选项[PD-exclude]可防止此问题。
The 3GPP link between the UE and the next-hop router (e.g., the GGSN) resembles a point-to-point (p2p) link, which has no link-layer addresses [RFC3316], and this has not changed from the 2G/3G GPRS to the EPS. The UE IP stack has to take this into consideration. When the 3GPP PDP context appears as a PPP interface/link to the UE, the IP stack is usually prepared to handle the Neighbor Discovery protocol and the related Neighbor Cache state machine transitions in an appropriate way, even though Neighbor Discovery protocol messages contain no link-layer address information. However, some operating systems discard Router Advertisements on their PPP interface/link as a default setting. This causes SLAAC to fail when the 3GPP PDP context gets established, thus stalling all IPv6 traffic.
UE和下一跳路由器（例如，GGSN）之间的3GPP链路类似于点对点（p2p）链路，其没有链路层地址[RFC3316]，并且这没有从2G/3G GPRS改变到EPS。UE IP堆栈必须考虑到这一点。当3GPP PDP上下文显示为到UE的PPP接口/链路时，IP堆栈通常准备以适当的方式处理邻居发现协议和相关的邻居缓存状态机转换，即使邻居发现协议消息不包含链路层地址信息。但是，一些操作系统将其PPP接口/链路上的路由器广告作为默认设置丢弃。这会导致SLAAC在3GPP PDP上下文建立时失败，从而暂停所有IPv6通信。
Currently, several operating systems and their network drivers can make the 3GPP PDP context appear as an IEEE 802 interface/link to the IP stack. This has a few known issues, especially when the IP stack is made to believe that the underlying link has link-layer addresses. First, the Neighbor Advertisement sent by a GGSN as a response to a Neighbor Solicitation triggered by address resolution might not contain a Target Link-Layer Address option (see Section 4.4 of [RFC4861]). It is then possible that the address resolution never completes when the UE tries to resolve the link-layer address of the GGSN, thus stalling all IPv6 traffic.
目前，一些操作系统及其网络驱动程序可以使3GPP PDP上下文显示为IP堆栈的IEEE 802接口/链路。这有一些已知的问题，特别是当IP堆栈认为底层链路具有链路层地址时。首先，GGSN发送的邻居公告作为对地址解析触发的邻居请求的响应，可能不包含目标链路层地址选项（参见[RFC4861]第4.4节）。然后，当UE尝试解析GGSN的链路层地址时，地址解析可能永远不会完成，从而暂停所有IPv6通信。
Second, the GGSN may simply discard all Neighbor Solicitation messages triggered by address resolution (as Section 2.4.1 of [RFC3316] is sometimes misinterpreted as saying that responding to address resolution and next-hop determination is not needed). As a result, the address resolution never completes when the UE tries to resolve the link-layer address of the GGSN, thus stalling all IPv6 traffic. There is little that can be done about this in the GGSN, assuming the neighbor-discovery implementation already does the right thing. But the UE stacks must be able to handle address resolution in the manner that they have chosen to represent the interface. In other words, if they emulate IEEE 802 interfaces, they also need to process Neighbor Discovery messages correctly.
其次，GGSN可以简单地丢弃由地址解析触发的所有邻居请求消息（如[RFC3316]第2.4.1节有时被误解为不需要响应地址解析和下一跳确定）。因此，当UE尝试解析GGSN的链路层地址时，地址解析永远不会完成，从而暂停所有IPv6通信。假设邻居发现实现已经做了正确的事情，那么在GGSN中可以做的很少。但是UE堆栈必须能够以它们选择的表示接口的方式处理地址解析。换句话说，如果他们模拟IEEE 802接口，他们还需要正确处理邻居发现消息。
3GPP standards prior to Release-8 provide IPv6 access for cellular devices with PDP contexts of type IPv6 [TS.23060]. For dual-stack access, a PDP context of type IPv6 is established in parallel to the PDP context of type IPv4, as shown in Figures 5 and 6. For IPv4-only service, connections are created over the PDP context of type IPv4,
第8版之前的3GPP标准为具有IPv6类型PDP上下文的蜂窝设备提供IPv6访问[TS.23060]。对于双栈访问，IPv6类型的PDP上下文与IPv4类型的PDP上下文并行建立，如图5和图6所示。对于仅IPv4服务，通过IPv4类型的PDP上下文创建连接，
and for IPv6-only service, connections are created over the PDP context of type IPv6. The two PDP contexts of different type may use the same APN (and the gateway); however, this aspect is not explicitly defined in standards. Therefore, cellular device and gateway implementations from different vendors may have varying support for this functionality.
对于仅限IPv6的服务，将通过IPv6类型的PDP上下文创建连接。不同类型的两个PDP上下文可以使用相同的APN（和网关）；但是，标准中没有明确定义这一方面。因此，来自不同供应商的蜂窝设备和网关实现可能对该功能有不同的支持。
Y .--.
| _(IPv4`.
|---+ +---+ +---+ ( PDN )
| D |~~~~~~~//-----| |====| |====( ` . ) )
| S | IPv4 context | S | | G | `--(___.-'
| | | G | | G | .--.
| U | | S | | S | _(IPv6`.
| E | IPv6 context | N | | N | ( PDN )
|///|~~~~~~~//-----| |====|(s)|====( ` . ) )
+---+ +---+ +---+ `--(___.-'
Y .--.
| _(IPv4`.
|---+ +---+ +---+ ( PDN )
| D |~~~~~~~//-----| |====| |====( ` . ) )
| S | IPv4 context | S | | G | `--(___.-'
| | | G | | G | .--.
| U | | S | | S | _(IPv6`.
| E | IPv6 context | N | | N | ( PDN )
|///|~~~~~~~//-----| |====|(s)|====( ` . ) )
+---+ +---+ +---+ `--(___.-'
Figure 5: Dual-Stack (DS) User Equipment Connecting to Both IPv4 and IPv6 Internet Using Parallel IPv4-Only and IPv6-Only PDP Contexts
图5：使用仅限IPv4和仅限IPv6的并行PDP上下文连接到IPv4和IPv6 Internet的双堆栈（DS）用户设备
Y
|
|---+ +---+ +---+
| D |~~~~~~~//-----| |====| | .--.
| S | IPv4 context | S | | G | _( DS `.
| | | G | | G | ( PDN )
| U | | S | | S |====( ` . ) )
| E | IPv6 context | N | | N | `--(___.-'
|///|~~~~~~~//-----| |====| |
+---+ +---+ +---+
Y
|
|---+ +---+ +---+
| D |~~~~~~~//-----| |====| | .--.
| S | IPv4 context | S | | G | _( DS `.
| | | G | | G | ( PDN )
| U | | S | | S |====( ` . ) )
| E | IPv6 context | N | | N | `--(___.-'
|///|~~~~~~~//-----| |====| |
+---+ +---+ +---+
Figure 6: Dual-Stack User Equipment Connecting to Dual-Stack Internet Using Parallel IPv4-Only and IPv6-Only PDP Contexts
图6：使用仅限IPv4和仅限IPv6的并行PDP上下文连接到双栈Internet的双栈用户设备
The approach of having parallel IPv4 and IPv6 types of PDP contexts open is not optimal, because two PDP contexts require double the signaling and consume more network resources than a single PDP context. In Figure 6, the IPv4 and IPv6 PDP contexts are attached to the same GGSN. While this is possible, the dual-stack MS may be attached to different GGSNs in the scenario where one GGSN supports IPv4 PDN connectivity while another GGSN provides IPv6 PDN connectivity.
开放并行IPv4和IPv6类型的PDP上下文的方法不是最优的，因为两个PDP上下文需要双倍的信令，并且比单个PDP上下文消耗更多的网络资源。在图6中，IPv4和IPv6 PDP上下文连接到相同的GGSN。虽然这是可能的，但在一个GGSN支持IPv4 PDN连接而另一个GGSN提供IPv6 PDN连接的情况下，双栈MS可以连接到不同的GGSN。
Since 3GPP Release-8, the powerful concept of a dual-stack type of PDN connection and EPS bearer has been introduced [TS.23401]. This enables parallel use of both IPv4 and IPv6 on a single bearer (IPv4v6), as illustrated in Figure 7, and makes dual stack simpler than in earlier 3GPP releases. As of Release-9, GPRS network nodes also support dual-stack (IPv4v6) PDP contexts.
自3GPP Release-8以来，引入了双栈型PDN连接和EPS承载的强大概念[TS.23401]。这使得IPv4和IPv6能够在单个承载（IPv4v6）上并行使用，如图7所示，并使双栈比早期的3GPP版本更简单。从第9版开始，GPRS网络节点还支持双栈（IPv4v6）PDP上下文。
Y
|
|---+ +---+ +---+
| D | | | | P | .--.
| S | | | | D | _( DS `.
| | IPv4v6 (DS) | S | | N | ( PDN )
| U |~~~~~~~//-----| G |====| - |====( ` . ) )
| E | bearer | W | | G | `--(___.-'
|///| | | | W |
+---+ +---+ +---+
Y
|
|---+ +---+ +---+
| D | | | | P | .--.
| S | | | | D | _( DS `.
| | IPv4v6 (DS) | S | | N | ( PDN )
| U |~~~~~~~//-----| G |====| - |====( ` . ) )
| E | bearer | W | | G | `--(___.-'
|///| | | | W |
+---+ +---+ +---+
Figure 7: Dual-Stack User Equipment Connecting to Dual-Stack Internet Using a Single IPv4v6 PDN Connection
图7：使用单个IPv4v6 PDN连接连接到双栈Internet的双栈用户设备
The following is a description of the various PDP contexts/PDN bearer types that are specified by 3GPP:
以下是由3GPP指定的各种PDP上下文/PDN承载类型的描述：
1. For 2G/3G access to the GPRS core (SGSN/GGSN) pre-Release-9, there are two IP PDP Types: IPv4 and IPv6. Two PDP contexts are needed to get dual-stack connectivity.
1. 对于对GPRS核心（SGSN/GGSN）预发布9的2G/3G访问，有两种IP PDP类型：IPv4和IPv6。需要两个PDP上下文来获得双堆栈连接。
2. For 2G/3G access to the GPRS core (SGSN/GGSN), starting with Release-9, there are three IP PDP Types: IPv4, IPv6, and IPv4v6. A minimum of one PDP context is needed to get dual-stack connectivity.
2. 对于GPRS核心（SGSN/GGSN）的2G/3G访问，从第9版开始，有三种IP PDP类型：IPv4、IPv6和IPv4v6。至少需要一个PDP上下文才能获得双堆栈连接。
3. For 2G/3G access to the EPC (PDN-GW via S4-SGSN), starting with Release-8, there are three IP PDP Types: IPv4, IPv6, and IPv4v6 (which gets mapped to the PDN connection type). A minimum of one PDP context is needed to get dual-stack connectivity.
3. 对于EPC的2G/3G访问（通过S4-SGSN的PDN-GW），从第8版开始，有三种IP PDP类型：IPv4、IPv6和IPv4v6（映射到PDN连接类型）。至少需要一个PDP上下文才能获得双堆栈连接。
4. For LTE (E-UTRAN) access to the EPC, starting with Release-8, there are three IP PDN Types: IPv4, IPv6, and IPv4v6. A minimum of one PDN connection is needed to get dual-stack connectivity.
4. 对于对EPC的LTE（E-UTRAN）访问，从第8版开始，有三种IP PDN类型：IPv4、IPv6和IPv4v6。至少需要一个PDN连接才能获得双堆栈连接。
The PDN connection establishment process is specified in detail in 3GPP specifications. Figure 8 illustrates the high-level process and signaling involved in the establishment of a PDN connection.
3GPP规范中详细规定了PDN连接建立过程。图8说明了建立PDN连接所涉及的高级过程和信令。
UE eNodeB/ MME SGW PDN-GW HSS/
| BS | | | AAA
| | | | | |
|---------->|(1) | | | |
| |---------->|(1) | | |
| | | | | |
|/---------------------------------------------------------\|
| Authentication and Authorization |(2)
|\---------------------------------------------------------/|
| | | | | |
| | |---------->|(3) | |
| | | |---------->|(3) |
| | | | | |
| | | |<----------|(4) |
| | |<----------|(4) | |
| |<----------|(5) | | |
|/---------\| | | | |
| RB setup |(6) | | | |
|\---------/| | | | |
| |---------->|(7) | | |
|---------->|(8) | | | |
| |---------->|(9) | | |
| | | | | |
|============= Uplink Data =========>==========>|(10) |
| | | | | |
| | |---------->|(11) | |
| | | | | |
| | |<----------|(12) | |
| | | | | |
|<============ Downlink Data =======<===========|(13) |
| | | | | |
UE eNodeB/ MME SGW PDN-GW HSS/
| BS | | | AAA
| | | | | |
|---------->|(1) | | | |
| |---------->|(1) | | |
| | | | | |
|/---------------------------------------------------------\|
| Authentication and Authorization |(2)
|\---------------------------------------------------------/|
| | | | | |
| | |---------->|(3) | |
| | | |---------->|(3) |
| | | | | |
| | | |<----------|(4) |
| | |<----------|(4) | |
| |<----------|(5) | | |
|/---------\| | | | |
| RB setup |(6) | | | |
|\---------/| | | | |
| |---------->|(7) | | |
|---------->|(8) | | | |
| |---------->|(9) | | |
| | | | | |
|============= Uplink Data =========>==========>|(10) |
| | | | | |
| | |---------->|(11) | |
| | | | | |
| | |<----------|(12) | |
| | | | | |
|<============ Downlink Data =======<===========|(13) |
| | | | | |
Figure 8: Simplified PDN Connection Setup Procedure in Release-8
图8:Release-8中简化的PDN连接设置程序
1. The UE (i.e., the MS) requires a data connection and hence decides to establish a PDN connection with a PDN-GW. The UE sends an "Attach" request (layer-2) to the base station (BS). The BS forwards this Attach request to the MME.
1. UE（即，MS）需要数据连接，因此决定与PDN-GW建立PDN连接。UE向基站（BS）发送“附加”请求（第2层）。BS将该连接请求转发给MME。
2. Authentication of the UE with the Authentication, Authorization, and Accounting (AAA) server/HSS follows. If the UE is authorized to establish a data connection, the process continues with the following steps:
2. 使用身份验证、授权和计费（AAA）服务器/HSS对UE进行身份验证。如果UE被授权建立数据连接，则该过程继续执行以下步骤：
3. The MME sends a "Create Session" request message to the SGW. The SGW forwards the Create Session request to the PDN-GW. The SGW knows the address of the PDN-GW to which it forwards the Create Session request as a result of this information having been obtained by the MME during the authentication/authorization phase.
3. MME向SGW发送“创建会话”请求消息。SGW将创建会话请求转发给PDN-GW。SGW知道PDN-GW的地址，由于MME在认证/授权阶段期间获得了该信息，SGW将创建会话请求转发到该PDN-GW。
The UE IPv4 address and/or IPv6 prefix gets assigned during this step. If a subscribed IPv4 address and/or IPv6 prefix is statically allocated for the UE for this APN, then the MME passes this previously allocated address information to the SGW and eventually to the PDN-GW in the Create Session request message. Otherwise, the PDN-GW manages the address assignment to the UE (there is another variation to this step where IPv4 address allocation is delayed until the UE initiates a DHCPv4 exchange, but this is not discussed here).
在此步骤中分配UE IPv4地址和/或IPv6前缀。如果为该APN的UE静态分配了订阅的IPv4地址和/或IPv6前缀，则MME将该先前分配的地址信息传递给SGW，并最终在创建会话请求消息中传递给PDN-GW。否则，PDN-GW管理到UE的地址分配（该步骤还有另一个变体，其中IPv4地址分配延迟到UE发起DHCPv4交换，但这里不讨论）。
4. The PDN-GW creates a PDN connection for the UE and sends a Create Session response message to the SGW from which the session request message was received. The SGW forwards the response to the corresponding MME that originated the request.
4. PDN-GW为UE创建PDN连接，并将创建会话响应消息发送到从其接收会话请求消息的SGW。SGW将响应转发给发起请求的相应MME。
5. The MME sends the "Attach Accept/Initial Context Setup" request message to the eNodeB/BS.
5. MME向eNodeB/BS发送“附加接受/初始上下文设置”请求消息。
6. The radio bearer (RB) between the UE and the eNodeB is reconfigured based on the parameters received from the MME. (See Note 1 below.)
6. 基于从MME接收的参数重新配置UE和eNodeB之间的无线电承载（RB）（参见下面的注释1）
7. The eNodeB sends an "Initial Context" response message to the MME.
7. eNodeB向MME发送“初始上下文”响应消息。
8. The UE sends a "Direct Transfer" message, which includes the "Attach Complete" signal, to the eNodeB.
8. UE向eNodeB发送包括“附加完成”信号的“直接传输”消息。
9. The eNodeB forwards the Attach Complete message to the MME.
9. eNodeB将附加完整消息转发给MME。
10. The UE can now start sending uplink packets to the PDN GW.
10. UE现在可以开始向PDN-GW发送上行链路分组。
11. The MME sends a "Modify Bearer" request message to the SGW.
11. MME向SGW发送“修改承载”请求消息。
12. The SGW responds with a Modify Bearer response message. At this time, the downlink connection is also ready.
12. SGW使用修改承载响应消息进行响应。此时，下行链路连接也准备就绪。
13. The UE can now start receiving downlink packets, including possible SLAAC-related IPv6 packets.
13. UE现在可以开始接收下行链路分组，包括可能的与SLAAC相关的IPv6分组。
The type of PDN connection established between the UE and the PDN-GW can be any of the types described in the previous section. The dual-stack PDN connection, i.e., the one that supports both IPv4 and IPv6 packets, is the default connection that will be established if no specific PDN connection type is specified by the UE in Release-8 networks.
在UE和PDN-GW之间建立的PDN连接的类型可以是前面部分中描述的任何类型。如果UE在Release-8网络中未指定特定的PDN连接类型，则将建立的默认连接是双栈PDN连接，即同时支持IPv4和IPv6数据包的连接。
Note 1: The UE receives the PDN Address Information Element [TS.24301] at the end of radio bearer setup messaging. This information element contains only the Interface Identifier of the IPv6 address. In the case of the GPRS, the PDP Address Information Element [TS.24008] would contain a complete IPv6 address. However, the UE must ignore the IPv6 prefix if it receives one in the message (see Section 11.2.1.3.2a of [TS.29061]).
注1：UE在无线承载设置消息传送结束时接收PDN地址信息元素[TS.24301]。此信息元素仅包含IPv6地址的接口标识符。对于GPRS，PDP地址信息元素[TS.24008]将包含完整的IPv6地址。但是，如果UE在消息中收到IPv6前缀，则必须忽略该前缀（参见[TS.29061]第11.2.1.3.2a节）。
3GPP discussed at length various approaches to support mobility between a Release-8 LTE network and a pre-Release-9 2G/3G network without an S4-SGSN for the new dual-stack bearers. The chosen approach for mobility is as follows, in short: if a UE is allowed to do handovers between a Release-8 LTE network and a pre-Release-9 2G/3G network without an S4-SGSN while having open PDN connections, only single-stack bearers are used. Essentially, this indicates the following deployment options:
3GPP详细讨论了支持Release-8 LTE网络和pre-Release-9 2G/3G网络之间的移动性的各种方法，其中不包括用于新的双栈承载的S4-SGSN。简言之，所选择的移动性方法如下：如果允许UE在具有开放PDN连接的情况下，在没有S4-SGSN的情况下在Release-8 LTE网络和pre-Release-9 2G/3G网络之间进行切换，则仅使用单栈承载。本质上，这表示以下部署选项：
1. If a network knows a UE may do handovers between a Release-8 LTE network and a pre-Release-9 2G/3G network without an S4-SGSN, then the network is configured to provide only single-stack bearers, even if the UE requests dual-stack bearers.
1. 如果网络知道UE可以在没有S4-SGSN的版本8 LTE网络和版本9之前的2G/3G网络之间进行切换，则网络被配置为仅提供单栈承载，即使UE请求双栈承载。
2. If the network knows the UE does handovers only between a Release-8 LTE network and a Release-9 2G/3G network or a pre-Release-9 network with an S4-SGSN, then the network is configured to provide the UE with dual-stack bearers on request. The same also applies for LTE-only deployments.
2. 如果网络知道UE仅在Release-8 LTE网络和Release-9 2G/3G网络或具有S4-SGSN的pre-Release-9网络之间进行切换，则该网络被配置为根据请求向UE提供双栈承载。这同样适用于仅LTE部署。
When a network operator and their roaming partners have upgraded their networks to Release-8, it is possible to use the new IPv4v6 dual-stack bearers. A Release-8 UE always requests a dual-stack bearer, but accepts what is assigned by the network.
当网络运营商及其漫游合作伙伴将其网络升级到Release-8时，可以使用新的IPv4v6双堆栈承载。Release-8 UE始终请求双栈承载，但接受网络分配的内容。
3GPP networks can natively transport IPv4 and IPv6 packets between the UE and the gateway (GGSN or PDN-GW) as a result of establishing either a dual-stack PDP context or parallel IPv4 and IPv6 PDP contexts.
3GPP网络可以在UE和网关（GGSN或PDN-GW）之间本地传输IPv4和IPv6分组，这是建立双栈PDP上下文或并行IPv4和IPv6 PDP上下文的结果。
Current deployments of 3GPP networks primarily support IPv4 only. These networks can be upgraded to also support IPv6 PDP contexts. By doing so, devices and applications that are IPv6 capable can start utilizing IPv6 connectivity. This will also ensure that legacy devices and applications continue to work with no impact. As newer devices start using IPv6 connectivity, the demand for actively used IPv4 connections is expected to slowly decrease, helping operators with a transition to IPv6. With a dual-stack approach, there is always the potential to fall back to IPv4. A device that may be roaming in a network wherein IPv6 is not supported by the visited network could fall back to using IPv4 PDP contexts, and hence the end user would at least get some connectivity. Unfortunately, the dual-stack approach as such does not lower the number of used IPv4 addresses. Every dual-stack bearer still needs to be given an IPv4 address, private or public. This is a major concern with dual-stack bearers concerning IPv6 transition. However, if the majority of active IP communication has moved over to IPv6, then in the case of Network Address Translation from IPv4 to IPv4 (NAT44), the number of active NAT44-translated IPv4 connections can still be expected to gradually decrease and thus give some level of relief regarding NAT44 function scalability.
目前3GPP网络的部署主要只支持IPv4。这些网络可以升级以支持IPv6 PDP上下文。通过这样做，支持IPv6的设备和应用程序可以开始利用IPv6连接。这还将确保遗留设备和应用程序继续工作而不受影响。随着新设备开始使用IPv6连接，对积极使用的IPv4连接的需求预计将缓慢减少，这有助于运营商过渡到IPv6。使用双栈方法，总是有可能退回到IPv4。在访问的网络不支持IPv6的网络中漫游的设备可能会退回到使用IPv4 PDP上下文，因此最终用户至少会获得一些连接。不幸的是，双栈方法本身并没有减少使用的IPv4地址的数量。每个双栈承载仍然需要提供一个IPv4地址，私有或公共。这是有关IPv6转换的双堆栈承载的主要问题。但是，如果大多数主动IP通信已转移到IPv6，则在从IPv4到IPv4的网络地址转换（NAT44）的情况下，主动NAT44转换的IPv4连接的数量仍将逐渐减少，从而在一定程度上缓解NAT44功能的可伸缩性。
As the networks evolve to support Release-8 EPS architecture and the dual-stack PDP contexts, newer devices will be able to leverage such capability and have a single bearer that supports both IPv4 and IPv6. Since IPv4 and IPv6 packets are carried as payload within GTP between the MS and the gateway (GGSN/PDN-GW), the transport-network capability in terms of whether it supports IPv4 or IPv6 on the interfaces between the eNodeB and SGW or between the SGW and PDN-GW is immaterial.
随着网络发展到支持Release-8 EPS体系结构和双栈PDP上下文，较新的设备将能够利用这种能力，并具有支持IPv4和IPv6的单一承载。由于IPv4和IPv6数据包作为有效负载在MS和网关（GGSN/PDN-GW）之间的GTP内进行传输，因此传输网络的能力在eNodeB和SGW之间或SGW和PDN-GW之间的接口上是否支持IPv4或IPv6是无关紧要的。
Given the shortage of globally routable public IPv4 addresses, operators tend to assign private IPv4 addresses [RFC1918] to UEs when they establish an IPv4-only PDP context or an IPv4v6 PDN context. About 16 million UEs can be assigned a private IPv4 address that is unique within a domain. However, for many operators, the number of subscribers is greater than 16 million. The issue can be dealt with by assigning overlapping RFC 1918 IPv4 addresses to UEs. As a result, the IPv4 address assigned to a UE within the context of a single operator realm would no longer be unique. This has the obvious and known issues of NATed IP connections in the Internet. Direct UE-to-UE connectivity becomes complicated; unless the UEs are within the same private address range pool and/or anchored to the same gateway, referrals using IP addresses will have issues, and so forth. These are generic issues and not only a concern of the EPS. However, 3GPP as such does not have any mandatory language concerning NAT44 functionality in the EPC. Obvious deployment choices apply also to the EPC:
由于缺少全局可路由的公共IPv4地址，运营商在建立仅IPv4 PDP上下文或IPv4v6 PDN上下文时，往往会将专用IPv4地址[RFC1918]分配给UE。可以为大约1600万个UE分配一个域内唯一的专用IPv4地址。然而，对于许多运营商来说，用户数量超过1600万。这个问题可以通过向ue分配重叠的RFC 1918 IPv4地址来解决。因此，在单个运营商领域的上下文中分配给UE的IPv4地址将不再是唯一的。这就存在着明显的和已知的互联网IP连接问题。直接UE到UE的连接变得复杂；除非ue在同一私有地址范围池内和/或锚定到同一网关，否则使用IP地址的转介将有问题，等等。这些是一般性问题，而不仅仅是EPS关注的问题。然而，3GPP本身没有关于EPC中的NAT44功能的任何强制性语言。明显的部署选择也适用于EPC：
1. Very large network deployments are partitioned, for example, based on geographical areas. This partitioning allows overlapping IPv4 address ranges to be assigned to UEs that are in different areas. Each area has its own pool of gateways that are dedicated to a certain overlapping IPv4 address range (also referred to as a zone). Standard NAT44 functionality allows for communication from the [RFC1918] private zone to the Internet. Communication between zones requires special arrangement, such as using intermediate gateways (e.g., a Back-to-Back User Agent (B2BUA) in the case of SIP).
1. 例如，非常大的网络部署是基于地理区域进行分区的。此分区允许将重叠的IPv4地址范围分配给位于不同区域的UE。每个区域都有自己的网关池，专用于某个重叠的IPv4地址范围（也称为区域）。标准NAT44功能允许从[RFC1918]专用区域到Internet的通信。区域之间的通信需要特殊安排，例如使用中间网关（例如，在SIP的情况下使用背靠背用户代理（B2BUA））。
2. A UE attaches to a gateway as part of the Attach process. The number of UEs that a gateway supports is on the order of 1 to 10 million. Hence, all of the UEs assigned to a single gateway can be assigned private IPv4 addresses. Operators with large subscriber bases have multiple gateways, and hence the same [RFC1918] IPv4 address space can be reused across gateways. The IPv4 address assigned to a UE is unique within the scope of a single gateway.
2. UE作为连接过程的一部分连接到网关。网关支持的UE数量大约为100万到1000万。因此，可以为分配给单个网关的所有ue分配专用IPv4地址。用户基数较大的运营商有多个网关，因此相同的[RFC1918]IPv4地址空间可以跨网关重用。分配给UE的IPv4地址在单个网关的范围内是唯一的。
3. New services requiring direct connectivity between UEs should be built on IPv6. Possible existing IPv4-only services and applications requiring direct connectivity can be ported to IPv6.
3. 需要UE之间直接连接的新服务应构建在IPv6上。可能存在的仅IPv4服务和需要直接连接的应用程序可以移植到IPv6。
The various reference points of the 3GPP architecture, such as S1-U, S5, and S8, are based on either GTP or PMIPv6. The underlying transport for these reference points can be IPv4 or IPv6. GTP has been able to operate over IPv6 transport (optionally) since R99, and PMIPv6 has supported IPv6 transport since its introduction in Release-8. The user-plane traffic between the UE and the gateway can use either IPv4 or IPv6. These packets are essentially treated as payload by GTP/PMIPv6 and transported accordingly, with no real attention paid (at least from a routing perspective) to the information contained in the IPv4 or IPv6 headers. The transport links between the eNodeB and the SGW, and the link between the SGW and PDN-GW, can be migrated to IPv6 without any direct implications to the architecture.
3GPP架构的各种参考点，例如S1-U、S5和S8，基于GTP或PMIPv6。这些参考点的底层传输可以是IPv4或IPv6。自R99以来，GTP已经能够通过IPv6传输（可选）运行，而PMIPv6自其在第8版中引入以来就支持IPv6传输。UE和网关之间的用户平面流量可以使用IPv4或IPv6。这些数据包基本上被GTP/PMIPv6视为有效负载，并相应地进行传输，而没有真正关注（至少从路由角度来看）IPv4或IPv6报头中包含的信息。eNodeB和SGW之间的传输链路以及SGW和PDN-GW之间的链路可以迁移到IPv6，而不会对体系结构产生任何直接影响。
Currently, the inter-operator (for 3GPP technology) roaming networks are all IPv4 only (see Inter-PLMN Backbone Guidelines [GSMA.IR.34]). Eventually, these roaming networks will also get migrated to IPv6, if there is a business reason for that. The migration period can be prolonged considerably, because the 3GPP protocols always tunnel user-plane traffic in the core network, and as described earlier, the transport-network IP version is not in any way tied to the user-plane IP version. Furthermore, the design of the inter-operator roaming networks is such that the user-plane and transport-network IP addressing schemes are completely separated from each other. The inter-operator roaming network itself is also completely separated from the Internet. Only those core network nodes that must be connected to the inter-operator roaming networks are actually visible there, and are able to send and receive (tunneled) traffic within the inter-operator roaming networks. Obviously, in order for the roaming to work properly, the operators have to agree on supported protocol versions so that the visited network does not, for example, unnecessarily drop user-plane IPv6 traffic.
目前，运营商间（对于3GPP技术）漫游网络都是仅IPv4的（请参阅PLMN间主干网指南[GSMA.IR.34]）。最终，如果有商业原因的话，这些漫游网络也将迁移到IPv6。迁移周期可以显著延长，因为3GPP协议总是在核心网络中隧道用户平面业务，并且如前所述，传输网络IP版本以任何方式都不与用户平面IP版本绑定。此外，运营商间漫游网络的设计使得用户平面和传输网络IP寻址方案彼此完全分离。运营商间漫游网络本身也与互联网完全分离。只有那些必须连接到运营商间漫游网络的核心网络节点才在那里实际可见，并且能够在运营商间漫游网络内发送和接收（隧道）流量。显然，为了使漫游正常工作，运营商必须就支持的协议版本达成一致，以便访问的网络不会（例如）不必要地丢弃用户平面IPv6流量。
Operating dual-stack networks does imply cost and complexity to a certain extent. However, these factors are mitigated by the assurance that legacy devices and services are unaffected, and there is always a fallback to IPv4 in case of issues with the IPv6 deployment or network elements. The model also enables operators to develop operational experience and expertise in an incremental manner.
操作双栈网络在一定程度上意味着成本和复杂性。但是，通过保证遗留设备和服务不受影响，这些因素得到了缓解，并且在IPv6部署或网络元素出现问题时，总是会退回到IPv4。该模型还使运营商能够以增量方式发展运营经验和专业知识。
Running dual-stack networks requires the management of multiple IP address spaces. Tracking of UEs needs to be expanded, since it can be identified by either an IPv4 address or an IPv6 prefix. Network elements will also need to be dual-stack capable in order to support the dual-stack deployment model.
运行双栈网络需要管理多个IP地址空间。UE的跟踪需要扩展，因为它可以通过IPv4地址或IPv6前缀来识别。为了支持双栈部署模型，网元还需要具有双栈能力。
Deployment and migration cases (see Section 6.1) for providing dual-stack capability may mean doubled resource usage in an operator's network. This is a major concern against providing dual-stack connectivity using techniques discussed in Section 6.1. Also, handovers between networks with different capabilities in terms of whether or not networks are capable of dual-stack service may prove difficult for users to comprehend and for applications/services to cope with. These facts may add other than just technical concerns for operators when planning to roll out dual-stack service offerings.
提供双堆栈功能的部署和迁移案例（见第6.1节）可能意味着运营商网络中的资源使用率翻倍。这是使用第6.1节中讨论的技术提供双堆栈连接的主要问题。此外，就网络是否能够提供双栈服务而言，具有不同能力的网络之间的切换对于用户和应用程序/服务来说可能难以理解。当运营商计划推出双栈服务时，这些事实可能会增加除技术问题以外的其他问题。
It is possible to allocate IPv6-only bearers to UEs in 3GPP networks. The IPv6-only bearer has been part of the 3GPP specification since the beginning. In 3GPP Release-8 (and later), it was defined that a dual-stack UE (or when the radio equipment has no knowledge of the UE IP stack's capabilities) must first attempt to establish a dual-stack bearer and then possibly fall back to a single-stack bearer. A Release-8 (or later) UE with an IPv6-only stack can directly attempt to establish an IPv6-only bearer. The IPv6-only behavior is up to subscription provisioning or PDN-GW configuration, and the fallback scenarios do not necessarily cause additional signaling.
在3GPP网络中，可以将仅IPv6承载分配给ue。仅IPv6承载从一开始就是3GPP规范的一部分。在3GPP版本8（及更高版本）中，定义了双栈UE（或当无线电设备不知道UE IP栈的能力时）必须首先尝试建立双栈承载，然后可能退回到单栈承载。具有仅IPv6堆栈的8版（或更高版本）UE可以直接尝试建立仅IPv6承载。仅IPv6的行为取决于订阅供应或PDN-GW配置，回退方案不一定会导致额外的信令。
Although the bullets below introduce IPv6-to-IPv4 address translation and specifically discuss NAT64 technology [RFC6144], the current 3GPP Release-8 architecture does not describe the use of address translation or NAT64. It is up to a specific deployment whether address translation is part of the network or not. The following are some operational aspects to consider for running a network with IPv6-only bearers:
尽管下面的项目介绍了IPv6到IPv4的地址转换，并专门讨论了NAT64技术[RFC6144]，但当前的3GPP Release-8体系结构并未描述地址转换或NAT64的使用。地址转换是否是网络的一部分取决于具体的部署。下面是运行IPv6唯一承载网络的一些操作方面的考虑：
o The UE must have an IPv6-capable stack and a radio interface capable of establishing an IPv6 PDP context or PDN connection.
o UE必须具有支持IPv6的堆栈和能够建立IPv6 PDP上下文或PDN连接的无线电接口。
o The GGSN/PDN-GW must be IPv6 capable in order to support IPv6 bearers. Furthermore, the SGSN/MME must allow the creation of a PDP Type or PDN Type of IPv6.
o GGSN/PDN-GW必须支持IPv6，以支持IPv6承载。此外，SGSN/MME必须允许创建IPv6的PDP类型或PDN类型。
o Many of the common applications are IP version agnostic and hence would work using an IPv6 bearer. However, applications that are IPv4 specific would not work.
o 许多常见的应用程序与IP版本无关，因此可以使用IPv6承载。但是，特定于IPv4的应用程序将无法工作。
o Inter-operator roaming is another aspect that causes issues, at least during the ramp-up phase of the IPv6 deployment. If the visited network to which outbound roamers attach does not support PDP/PDN Type IPv6, then there needs to be a fallback option. The fallback option in this specific case is mostly up to the UE to implement. Several cases are discussed in the following sections.
o 运营商间漫游是导致问题的另一个方面，至少在IPv6部署的提升阶段是如此。如果出站漫游者连接到的访问网络不支持PDP/PDN类型的IPv6，则需要有一个回退选项。在这种特定情况下，回退选项主要由UE来实现。下面几节将讨论几个案例。
o If and when a UE using an IPv6-only bearer needs access to the IPv4 Internet/network, some type of translation from IPv6 to IPv4 has to be deployed in the network. NAT64 (or DNS64) is one solution that can be used for this purpose and works for a certain set of protocols (read TCP, UDP, and ICMP, and when applications actually use DNS for resolving names to IP addresses).
o 如果并且当使用仅IPv6承载的UE需要访问IPv4 Internet/网络时，必须在网络中部署某种类型的从IPv6到IPv4的转换。NAT64（或DNS64）是一种可用于此目的的解决方案，适用于特定的协议集（读取TCP、UDP和ICMP，以及应用程序实际使用DNS将名称解析为IP地址）。
Roaming was briefly touched upon in Sections 8.2 and 8.4. While there is interest in offering roaming service for IPv6-enabled UEs and subscriptions, not all visited networks are prepared for IPv6 outbound roamers:
第8.2节和第8.4节简要介绍了漫游。虽然有兴趣为支持IPv6的UE和订阅提供漫游服务，但并非所有访问的网络都为IPv6出站漫游者做好了准备：
o The visited-network SGSN does not support the IPv6 PDP context or IPv4v6 PDP context types. These should mostly concern pre-Release-9 2G/3G networks without an S4-SGSN, but there is no definitive rule, as the deployed feature sets vary depending on implementations and licenses.
o 访问的网络SGSN不支持IPv6 PDP上下文或IPv4v6 PDP上下文类型。这些应该主要关注没有S4-SGSN的预发布9 2G/3G网络，但没有明确的规则，因为部署的功能集因实施和许可证而异。
o The visited network might not be commercially ready for IPv6 outbound roamers, while everything might work technically at the user-plane level. This would lead to "revenue leakage", especially from the visited operator's point of view (note that the use of a visited-network GGSN/PDN-GW does not really exist today in commercial deployments for data roaming).
o 访问的网络可能还没有为IPv6出站漫游者做好商业上的准备，而在技术上，一切都可能在用户层面上起作用。这将导致“收入泄漏”，特别是从到访运营商的角度来看（请注意，在数据漫游的商业部署中，目前还不存在使用到访网络GGSN/PDN-GW）。
It might be in the interest of operators to prohibit roaming selectively within specific visited networks until IPv6 roaming is in place. 3GPP does not specify a mechanism whereby IPv6 roaming is prohibited without also disabling IPv4 access and other packet services. The following options for disabling IPv6 access for roaming subscribers could be available in some network deployments:
在IPv6漫游到位之前，运营商有选择地禁止在特定访问网络内漫游可能符合其利益。3GPP没有指定一种机制，即在不禁用IPv4访问和其他分组服务的情况下禁止IPv6漫游。在某些网络部署中，可以使用以下选项禁用漫游订户的IPv6访问：
o Policy and Charging Control (PCC) [TS.23203] functionality and its rules, for example, could be used to cause bearer authorization to fail when a desired criteria is met. In this case, that would be PDN/PDP Type IPv6/IPv4v6 and a specific visited network. The rules can be provisioned either in the home network or locally in the visited network.
o 例如，策略和计费控制（PCC）[TS.23203]功能及其规则可用于在满足所需标准时导致承载授权失败。在本例中，这将是PDN/PDP类型的IPv6/IPv4v6和特定的访问网络。这些规则可以在家庭网络中设置，也可以在访问的网络中本地设置。
o Some Home Location Register (HLR) and Home Subscriber Server (HSS) subscriber databases allow prohibiting roaming in a specific (visited) network for a specified PDN/PDP Type.
o 某些归属位置寄存器（HLR）和归属订户服务器（HSS）订户数据库允许禁止在指定PDN/PDP类型的特定（已访问）网络中漫游。
The obvious problems are that these solutions are not mandatory, are not unified across networks, and therefore also lack a well-specified fallback mechanism from the UE's point of view.
显而易见的问题是，这些解决方案不是强制性的，不是跨网络统一的，因此从UE的角度来看，还缺乏明确规定的回退机制。
It is obvious that as operators start to incrementally deploy the EPS along with the existing UTRAN/GERAN, handovers between different radio technologies (inter-RAT handovers) become inevitable. In the case of inter-RAT handovers, 3GPP supports the following IP addressing scenarios:
显然，随着运营商开始逐步部署EPS以及现有的UTRAN/GERAN，不同无线技术之间的切换（RAT间切换）变得不可避免。在RAT间切换的情况下，3GPP支持以下IP寻址场景：
o The E-UTRAN IPv4v6 bearer has to map one to one to the UTRAN/GERAN IPv4v6 bearer.
o E-UTRAN IPv4v6承载必须将一对一映射到UTRAN/GERAN IPv4v6承载。
o The E-UTRAN IPv6 bearer has to map one to one to the UTRAN/GERAN IPv6 bearer.
o E-UTRAN IPv6承载必须将一对一映射到UTRAN/GERAN IPv6承载。
o The E-UTRAN IPv4 bearer has to map one to one to the UTRAN/GERAN IPv4 bearer.
o E-UTRAN IPv4承载必须将一对一映射到UTRAN/GERAN IPv4承载。
Other types of configurations are not standardized. The above rules essentially imply that the network migration has to be planned and subscriptions provisioned based on the lowest common denominator, if inter-RAT handovers are desired. For example, if some part of the UTRAN cannot serve anything but IPv4 bearers, then the E-UTRAN is also forced to provide only IPv4 bearers. Various combinations of subscriber provisioning regarding IP versions are discussed further in Section 8.7.
其他类型的配置没有标准化。上述规则本质上意味着，如果需要RAT间切换，则必须根据最低公分母规划网络迁移和提供订阅。例如，如果UTRAN的某个部分只能提供IPv4承载，那么E-UTRAN也被迫只提供IPv4承载。第8.7节将进一步讨论关于IP版本的订户配置的各种组合。
8.7. Provisioning of IPv6 Subscribers and Various Combinations during Initial Network Attachment
8.7. 在初始网络连接期间提供IPv6订户和各种组合
Subscribers' provisioned PDP/PDN Types have multiple configurations. The supported PDP/PDN Type is provisioned per each APN for every subscriber. The following PDN Types are possible in the HSS for a Release-8 subscription [TS.23401]:
订阅者配置的PDP/PDN类型具有多个配置。支持的PDP/PDN类型是为每个订户的每个APN提供的。对于第8版订阅[TS.23401]，HSS中可以使用以下PDN类型：
o IPv4v6 PDN Type (note that the IPv4v6 PDP Type does not exist in an HLR and Mobile Application Part (MAP) [TS.29002] signaling prior to Release-9).
o IPv4v6 PDN类型（请注意，在9版之前的HLR和移动应用程序部件（MAP）[TS.29002]信令中不存在IPv4v6 PDP类型）。
o IPv6-only PDN Type.
o 仅限IPv6 PDN类型。
o IPv4-only PDN Type.
o 仅IPv4 PDN类型。
o IPv4_or_IPv6 PDN Type (note that the IPv4_or_IPv6 PDP Type does not exist in an HLR or MAP signaling. However, an HLR may have multiple APN configurations of different PDN Types; these configurations would effectively achieve the same functionality).
o IPv4_或_IPv6 PDN类型（请注意，HLR或MAP信令中不存在IPv4_或_IPv6 PDP类型。但是，HLR可能具有不同PDN类型的多个APN配置；这些配置将有效地实现相同的功能）。
A Release-8 dual-stack UE must always attempt to establish a PDP/PDN Type IPv4v6 bearer. The same also applies when the modem part of the UE does not have exact knowledge of whether the UE operating system IP stack is dual-stack capable or not. A UE that is IPv6-only capable must attempt to establish a PDP/PDN Type IPv6 bearer. Last, a UE that is IPv4-only capable must attempt to establish a PDN/PDP Type IPv4 bearer.
Release-8双栈UE必须始终尝试建立PDP/PDN类型的IPv4v6承载。当UE的调制解调器部分不确切知道UE操作系统IP堆栈是否具有双堆栈能力时，同样适用。仅支持IPv6的UE必须尝试建立PDP/PDN类型的IPv6承载。最后，仅支持IPv4的UE必须尝试建立PDN/PDP类型的IPv4承载。
In a case where the PDP/PDN Type requested by a UE does not match what has been provisioned for the subscriber in the HSS (or HLR), the UE possibly falls back to a different PDP/PDN Type. The network (i.e., the MME or the S4-SGSN) is able to inform the UE during network attachment signaling as to why it did not get the requested PDP/PDN Type. These response/cause codes are documented in [TS.24008] for requested PDP Types and [TS.24301] for requested PDN Types:
在UE请求的PDP/PDN类型与在HSS（或HLR）中为订户提供的PDP/PDN类型不匹配的情况下，UE可能返回到不同的PDP/PDN类型。网络（即，MME或S4-SGSN）能够在网络连接信令期间通知UE为什么它没有获得请求的PDP/PDN类型。对于请求的PDP类型，这些响应/原因代码记录在[TS.24008]中；对于请求的PDN类型，这些响应/原因代码记录在[TS.24301]中：
o (E)SM cause #50 "PDN/PDP type IPv4 only allowed".
o （E） SM原因#50“仅允许PDN/PDP类型IPv4”。
o (E)SM cause #51 "PDN/PDP type IPv6 only allowed".
o （E） SM原因#51“仅允许PDN/PDP类型IPv6”。
o (E)SM cause #52 "single address bearers only allowed".
o （E） SM原因#52“仅允许单个地址承载”。
The above response/cause codes apply to Release-8 and onwards. In pre-Release-8 networks, the response/cause codes that are used vary, depending on the vendor, unfortunately.
上述响应/原因代码适用于第8版及以后版本。不幸的是，在pre-Release-8网络中，所使用的响应/原因代码因供应商而异。
Possible fallback cases when the network deploys MMEs and/or S4-SGSNs include (as documented in [TS.23401]):
网络部署MME和/或S4 SGSN时可能出现的回退情况包括（如[TS.23401]中所述）：
o Requested and provisioned PDP/PDN Types match => requested.
o 请求的和配置的PDP/PDN类型匹配=>请求的。
o Requested IPv4v6 and provisioned IPv6 => IPv6, and a UE receives an indication that an IPv6-only bearer is allowed.
o 请求的IPv4v6和配置的IPv6=>IPv6，并且UE接收到仅允许IPv6承载的指示。
o Requested IPv4v6 and provisioned IPv4 => IPv4, and the UE receives an indication that an IPv4-only bearer is allowed.
o 请求的IPv4v6和配置的IPv4=>IPv4，并且UE接收到仅允许IPv4承载的指示。
o Requested IPv4v6 and provisioned IPv4_or_IPv6 => IPv4 or IPv6 is selected by the MME/S4-SGSN based on an unspecified criteria. The UE may then attempt to establish, based on the UE implementation, a parallel bearer of a different PDP/PDN Type.
o MME/S4-SGSN根据未指定的标准选择请求的IPv4v6和配置的IPv4\u或\u IPv6=>IPv4或IPv6。然后，UE可以基于UE实现尝试建立不同PDP/PDN类型的并行承载。
o Other combinations cause the bearer establishment to fail.
o 其他组合导致承载建立失败。
In addition to PDP/PDN Types provisioned in the HSS, it is also possible for a PDN-GW (and an MME/S4-SGSN) to affect the final selected PDP/PDN Type:
除HSS中规定的PDP/PDN类型外，PDN-GW（和MME/S4-SGSN）也可能影响最终选择的PDP/PDN类型：
o Requested IPv4v6 and configured IPv4 or IPv6 in the PDN-GW => IPv4 or IPv6. If the MME operator had included the "Dual Address Bearer" flag in the bearer establishment signaling, then the UE would have received an indication that an IPv6-only or IPv4-only bearer is allowed.
o 在PDN-GW=>IPv4或IPv6中请求IPv4v6并配置IPv4或IPv6。如果MME运营商已在承载建立信令中包括“双地址承载”标志，则UE将已接收到仅允许IPv6或仅允许IPv4承载的指示。
o Requested IPv4v6 and configured IPv4 or IPv6 in the PDN-GW => IPv4 or IPv6. If the MME operator had not included the "Dual Address Bearer" flag in the bearer establishment signaling, then the UE may have attempted to establish, based on the UE implementation, a parallel bearer of a different PDP/PDN Type.
o 在PDN-GW=>IPv4或IPv6中请求IPv4v6并配置IPv4或IPv6。如果MME运营商没有在承载建立信令中包括“双地址承载”标志，则UE可能已经尝试基于UE实现建立不同PDP/PDN类型的并行承载。
An SGSN that does not understand the requested PDP Type is supposed to handle the requested PDP Type as IPv4. If for some reason an MME does not understand the requested PDN Type, then the PDN Type is handled as IPv6.
不理解请求的PDP类型的SGSN应将请求的PDP类型作为IPv4处理。如果出于某种原因MME不理解请求的PDN类型，则PDN类型将作为IPv6处理。
This document does not introduce any security-related concerns. Section 5 of [RFC3316] already contains an in-depth discussion of IPv6-related security considerations in 3GPP networks prior to Release-8. This section discusses a few additional security concerns to take into consideration.
本文件不涉及任何与安全相关的问题。[RFC3316]的第5节已经深入讨论了第8版之前3GPP网络中与IPv6相关的安全注意事项。本节讨论一些需要考虑的其他安全问题。
In 3GPP access, the UE and the network always perform a mutual authentication during the network attachment [TS.33102] [TS.33401]. Furthermore, each time a PDP context/PDN connection gets created, a new connection, a modification of an existing connection, and an assignment of an IPv6 prefix or an IP address can be authorized against the PCC infrastructure [TS.23203] and/or PDN's AAA server.
在3GPP接入中，UE和网络总是在网络连接期间执行相互认证[TS.33102][TS.33401]。此外，每次创建PDP上下文/PDN连接时，可以针对PCC基础设施[TS.23203]和/或PDN的AAA服务器授权新连接、修改现有连接以及分配IPv6前缀或IP地址。
The wireless part of the 3GPP link between the UE and the (e)NodeB as well as the signaling messages between the UE and the MME/SGSN can be protected, depending on the regional regulation and the operator's deployment policy. User-plane traffic can be confidentiality protected. The control plane is always at least integrity and replay
根据区域法规和运营商的部署策略，可以保护UE和（e）NodeB之间的3GPP链路的无线部分以及UE和MME/SGSN之间的信令消息。可以对用户平面通信进行保密保护。控制平面始终至少保持完整性和可重放性
protected, and may also be confidentiality protected. The protection within the transmission part of the network depends on the operator's deployment policy [TS.33401].
受保护，也可能受保密保护。网络传输部分内的保护取决于运营商的部署策略[TS.33401]。
Several of the on-link and neighbor-discovery-related attacks can be mitigated due to the nature of the 3GPP point-to-point link model, and the fact that the UE and the first-hop router (PDN-GW/GGSN or SGW) are the only nodes on the link. For off-link IPv6 attacks, the 3GPP EPS is as vulnerable as any IPv6 system.
由于3GPP点到点链路模型的性质，以及UE和第一跳路由器（PDN-GW/GGSN或SGW）是链路上的唯一节点这一事实，可以缓解一些与链路上和邻居发现相关的攻击。对于脱离链路的IPv6攻击，3GPP EPS与任何IPv6系统一样容易受到攻击。
There have also been concerns that the UE IP stack might use permanent subscriber identities, such as an International Mobile Subscriber Identity (IMSI), as the source for the IPv6 address Interface Identifier. This would be a privacy threat and would allow tracking of subscribers. Therefore, the use of an IMSI (or any identity defined by [TS.23003]) as the Interface Identifier is prohibited [TS.23401]. However, there is no standardized method to block such misbehaving UEs.
还存在这样的担忧，即UE IP堆栈可能使用永久用户标识，例如国际移动用户标识（IMSI），作为IPv6地址接口标识符的源。这将对隐私构成威胁，并允许跟踪订阅者。因此，禁止使用IMSI（或[TS.23003]定义的任何标识）作为接口标识符[TS.23401]。然而，没有标准化的方法来阻止这种行为不端的UE。
The 3GPP network architecture and specifications enable the establishment of IPv4 and IPv6 connections through the use of appropriate PDP context types. The current generation of deployed networks can support dual-stack connectivity if the packet core network elements, such as the SGSN and GGSN, have that capability. With Release-8, 3GPP has specified a more optimal PDP context type that enables the transport of IPv4 and IPv6 packets within a single PDP context between the UE and the gateway.
3GPP网络体系结构和规范允许通过使用适当的PDP上下文类型来建立IPv4和IPv6连接。如果分组核心网络元素（例如SGSN和GGSN）具有该能力，则当前一代部署的网络可以支持双栈连接。在Release-8中，3GPP指定了一种更优化的PDP上下文类型，该类型支持在UE和网关之间的单个PDP上下文中传输IPv4和IPv6数据包。
As devices and applications are upgraded to support IPv6, they can start leveraging the IPv6 connectivity provided by the networks while maintaining the ability to fall back to IPv4. Enabling IPv6 connectivity in the 3GPP networks by itself will provide some degree of relief to the IPv4 address space, as many of the applications and services can start to work over IPv6. However, without comprehensive testing of current widely used applications and solutions for their ability to operate over IPv6 PDN connections, an IPv6-only access would cause disruptions.
随着设备和应用程序升级以支持IPv6，它们可以开始利用网络提供的IPv6连接，同时保持退回IPv4的能力。在3GPP网络中启用IPv6连接本身将在一定程度上缓解IPv4地址空间，因为许多应用程序和服务可以开始在IPv6上工作。但是，如果不全面测试当前广泛使用的应用程序和解决方案在IPv6 PDN连接上运行的能力，仅IPv6访问将导致中断。
The authors thank Shabnam Sultana, Sri Gundavelli, Hui Deng, Zhenqiang Li, Mikael Abrahamsson, James Woodyatt, Wes George, Martin Thomson, Russ Mundy, Cameron Byrne, Ales Vizdal, Frank Brockners, Adrian Farrel, Stephen Farrell, Paco Cortes, and Jari Arkko for their reviews and comments on this document.
作者感谢Shabnam Sultana、Sri Gundavelli、Hui Deng、Li Zhenjiang、Mikael Abrahamsson、James Woodyatt、Wes George、Martin Thomson、Russ Mundy、Cameron Byrne、Ales Vizdal、Frank Brockner、Adrian Farrel、Stephen Farrell、Paco Cortes和Jari Arkko对本文件的评论。
[GSMA.IR.34] GSMA, "Inter-PLMN Backbone Guidelines", GSMA PRD IR.34.4.9, March 2010.
[GSMA.IR.34]GSMA，“PLMN间主干指南”，GSMA PRD IR.34.4.92010年3月。
[PD-EXCLUDE] Korhonen, J., Ed., Savolainen, T., Krishnan, S., and O. Troan, "Prefix Exclude Option for DHCPv6-based Prefix Delegation", Work in Progress, December 2011.
[PD-EXCLUDE]Korhonen，J.，Ed.，Savolainen，T.，Krishnan，S.，和O.Troan，“基于DHCPv6前缀委托的前缀排除选项”，正在进行的工作，2011年12月。
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., and E. Lear, "Address Allocation for Private Internets", BCP 5, RFC 1918, February 1996.
[RFC1918]Rekhter，Y.，Moskowitz，B.，Karrenberg，D.，de Groot，G.，和E.Lear，“私人互联网地址分配”，BCP 5，RFC 1918，1996年2月。
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997.
[RFC2131]Droms，R.，“动态主机配置协议”，RFC21311997年3月。
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3315]Droms，R.，Ed.，Bound，J.，Volz，B.，Lemon，T.，Perkins，C.，和M.Carney，“IPv6的动态主机配置协议（DHCPv6）”，RFC3315，2003年7月。
[RFC3316] Arkko, J., Kuijpers, G., Soliman, H., Loughney, J., and J. Wiljakka, "Internet Protocol Version 6 (IPv6) for Some Second and Third Generation Cellular Hosts", RFC 3316, April 2003.
[RFC3316]Arkko，J.，Kuijpers，G.，Soliman，H.，Loughney，J.，和J.Wiljakka，“一些第二代和第三代蜂窝主机的互联网协议版本6（IPv6）”，RFC 3316，2003年4月。
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host Configuration Protocol (DHCP) version 6", RFC 3633, December 2003.
[RFC3633]Troan，O.和R.Droms，“动态主机配置协议（DHCP）版本6的IPv6前缀选项”，RFC 3633，2003年12月。
[RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol (DHCP) Service for IPv6", RFC 3736, April 2004.
[RFC3736]Droms，R.，“IPv6的无状态动态主机配置协议（DHCP）服务”，RFC 3736，2004年4月。
[RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery Proxies (ND Proxy)", RFC 4389, April 2006.
[RFC4389]Thaler，D.，Talwar，M.，和C.Patel，“邻居发现代理（ND代理）”，RFC 4389，2006年4月。
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007.
[RFC4861]Narten，T.，Nordmark，E.，Simpson，W.，和H.Soliman，“IP版本6（IPv6）的邻居发现”，RFC 48612007年9月。
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, September 2007.
[RFC4862]Thomson，S.，Narten，T.，和T.Jinmei，“IPv6无状态地址自动配置”，RFC 48622007年9月。
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 4941, September 2007.
[RFC4941]Narten，T.，Draves，R.，和S.Krishnan，“IPv6中无状态地址自动配置的隐私扩展”，RFC 49412007年9月。
[RFC5213] Gundavelli, S., Ed., Leung, K., Devarapalli, V., Chowdhury, K., and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC5213]Gundavelli，S.，Ed.，Leung，K.，Devarapalli，V.，Chowdhury，K.，和B.Patil，“代理移动IPv6”，RFC 5213，2008年8月。
[RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for IPv4/IPv6 Translation", RFC 6144, April 2011.
[RFC6144]Baker，F.，Li，X.，Bao，C.，和K.Yin，“IPv4/IPv6转换框架”，RFC 61442011年4月。
[TR.23975] 3GPP, "IPv6 Migration Guidelines", 3GPP TR 23.975 11.0.0, June 2011.
[TR.23975]3GPP，“IPv6迁移指南”，3GPP TR 23.975 11.0.012011年6月。
[TS.23003] 3GPP, "Numbering, addressing and identification", 3GPP TS 23.003 10.3.0, September 2011.
[TS.23003]3GPP，“编号、寻址和标识”，3GPP TS 23.003 10.3.012011年9月。
[TS.23060] 3GPP, "General Packet Radio Service (GPRS); Service description; Stage 2", 3GPP TS 23.060 8.14.0, September 2011.
[TS.23060]3GPP，“通用分组无线业务（GPRS）；业务描述；第2阶段”，3GPP TS 23.060 8.14.012011年9月。
[TS.23203] 3GPP, "Policy and charging control architecture", 3GPP TS 23.203 8.12.0, June 2011.
[TS.23203]3GPP，“策略和收费控制体系结构”，3GPP TS 23.203 8.12.012011年6月。
[TS.23401] 3GPP, "General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access", 3GPP TS 23.401 10.5.0, September 2011.
[TS.23401]3GPP，“通用分组无线业务（GPRS）增强，用于演进通用地面无线接入网（E-UTRAN）接入”，3GPP TS 23.401 10.5.012011年9月。
[TS.23402] 3GPP, "Architecture enhancements for non-3GPP accesses", 3GPP TS 23.402 10.5.0, September 2011.
[TS.23402]3GPP，“非3GPP接入的架构增强”，3GPP TS 23.402 10.5.012011年9月。
[TS.24008] 3GPP, "Mobile radio interface Layer 3 specification; Core network protocols; Stage 3", 3GPP TS 24.008 8.14.0, June 2011.
[TS.24008]3GPP，“移动无线接口第3层规范；核心网络协议；第3阶段”，3GPP TS 24.008 8.14.012011年6月。
[TS.24301] 3GPP, "Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3", 3GPP TS 24.301 8.10.0, June 2011.
[TS.24301]3GPP，“演进包系统（EPS）的非接入层（NAS）协议；第3阶段”，3GPP TS 24.301 8.10.012011年6月。
[TS.29002] 3GPP, "Mobile Application Part (MAP) specification", 3GPP TS 29.002 9.6.0, September 2011.
[TS.29002]3GPP，“移动应用部件（MAP）规范”，3GPP TS 29.002 9.6.012011年9月。
[TS.29060] 3GPP, "General Packet Radio Service (GPRS); GPRS Tunnelling Protocol (GTP) across the Gn and Gp interface", 3GPP TS 29.060 8.15.0, September 2011.
[TS.29060]3GPP，“通用分组无线业务（GPRS）；通过Gn和Gp接口的GPRS隧道协议（GTP）”，3GPP TS 29.060 8.15.012011年9月。
[TS.29061] 3GPP, "Interworking between the Public Land Mobile Network (PLMN) supporting packet based services and Packet Data Networks (PDN)", 3GPP TS 29.061 8.8.0, September 2011.
[TS.29061]3GPP，“支持分组业务的公共陆地移动网络（PLMN）与分组数据网络（PDN）之间的互通”，3GPP TS 29.061 8.8.012011年9月。
[TS.29274] 3GPP, "3GPP Evolved Packet System (EPS); Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C); Stage 3", 3GPP TS 29.274 8.10.0, June 2011.
[TS.29274]3GPP，“3GPP演进分组系统（EPS）；用于控制平面的演进通用分组无线业务（GPRS）隧道协议（GTPv2-C）；第3阶段”，3GPP TS 29.274 8.10.012011年6月。
[TS.29281] 3GPP, "General Packet Radio System (GPRS) Tunnelling Protocol User Plane (GTPv1-U)", 3GPP TS 29.281 10.3.0, September 2011.
[TS.29281]3GPP，“通用分组无线系统（GPRS）隧道协议用户平面（GTPv1-U）”，3GPP TS 29.281 10.3.012011年9月。
[TS.33102] 3GPP, "3G security; Security architecture", 3GPP TS 33.102 10.0.0, December 2010.
[TS.33102]3GPP，“3G安全；安全架构”，3GPP TS 33.102 10.0.012010年12月。
[TS.33401] 3GPP, "3GPP System Architecture Evolution (SAE); Security architecture", 3GPP TS 33.401 10.2.0, September 2011.
[TS.33401]3GPP，“3GPP系统架构演进（SAE）；安全架构”，3GPP TS 33.401 10.2.012011年9月。
Authors' Addresses
作者地址
Jouni Korhonen (editor) Nokia Siemens Networks Linnoitustie 6 FI-02600 Espoo FINLAND
Jouni Korhonen（编辑）诺基亚西门子网络公司Linnoitustie 6 FI-02600 Espoo芬兰
EMail: jouni.nospam@gmail.com
EMail: jouni.nospam@gmail.com
Jonne Soininen Renesas Mobile Porkkalankatu 24 FI-00180 Helsinki FINLAND
Jonne Soininen Renesas Mobile Porkkalankatu 24 FI-00180芬兰赫尔辛基
EMail: jonne.soininen@renesasmobile.com
EMail: jonne.soininen@renesasmobile.com
Basavaraj Patil Nokia 6021 Connection Drive Irving, TX 75039 USA
美国德克萨斯州欧文市Basavaraj Patil诺基亚6021连接驱动器75039
EMail: basavaraj.patil@nokia.com
EMail: basavaraj.patil@nokia.com
Teemu Savolainen Nokia Hermiankatu 12 D FI-33720 Tampere FINLAND
Teemu Savolainen诺基亚Hermiankatu 12 D FI-33720坦佩雷芬兰
EMail: teemu.savolainen@nokia.com
EMail: teemu.savolainen@nokia.com
Gabor Bajko Nokia 323 Fairchild Drive 6 Mountain View, CA 94043 USA
美国加利福尼亚州山景城Fairchild Drive 6 Gabor Bajko诺基亚323邮编94043
EMail: gabor.bajko@nokia.com
EMail: gabor.bajko@nokia.com
Kaisu Iisakkila Renesas Mobile Porkkalankatu 24 FI-00180 Helsinki FINLAND
Kaisu Iisakkila Renesas Mobile Porkkalankatu 24 FI-00180芬兰赫尔辛基
EMail: kaisu.iisakkila@renesasmobile.com
EMail: kaisu.iisakkila@renesasmobile.com