Network Working Group                                        J. Jee, Ed.
Request for Comments: 5154                                          ETRI
Category: Informational                                   S. Madanapalli
                                                      Ordyn Technologies
                                                               J. Mandin
                                                              April 2008
Network Working Group                                        J. Jee, Ed.
Request for Comments: 5154                                          ETRI
Category: Informational                                   S. Madanapalli
                                                      Ordyn Technologies
                                                               J. Mandin
                                                              April 2008

IP over IEEE 802.16 Problem Statement and Goals

IP over IEEE 802.16问题陈述和目标

Status of This Memo


This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.




This document specifies problems in running IP over IEEE 802.16 networks by identifying specific gaps in the IEEE 802.16 Media Access Control (MAC) for IPv4 and IPv6 support. This document also provides an overview of IEEE 802.16 network characteristics and convergence sublayers. Common terminology used for the base guideline while defining the solution framework is also presented.

本文档通过确定IPv4和IPv6支持的IEEE 802.16媒体访问控制(MAC)中的具体差距,详细说明在IEEE 802.16网络上运行IP的问题。本文档还概述了IEEE 802.16网络特性和汇聚子层。还介绍了定义解决方案框架时用于基本指南的通用术语。

Table of Contents


   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Overview of the IEEE 802.16 MAC Layer  . . . . . . . . . . . .  4
     3.1.  Transport Connections  . . . . . . . . . . . . . . . . . .  4
     3.2.  IEEE 802.16 PDU Format . . . . . . . . . . . . . . . . . .  5
     3.3.  IEEE 802.16 Convergence Sublayer . . . . . . . . . . . . .  5
   4.  IP over IEEE 802.16 Problem Statement and Goals  . . . . . . .  6
     4.1.  Root Problem . . . . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Point-to-Point Link Model for IP CS: Problems  . . . . . .  8
     4.3.  Ethernet-Like Link Model for Ethernet CS: Problems . . . .  9
     4.4.  IP over IEEE 802.16 Goals  . . . . . . . . . . . . . . . . 10
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   6.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 11
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 11
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 12
   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Overview of the IEEE 802.16 MAC Layer  . . . . . . . . . . . .  4
     3.1.  Transport Connections  . . . . . . . . . . . . . . . . . .  4
     3.2.  IEEE 802.16 PDU Format . . . . . . . . . . . . . . . . . .  5
     3.3.  IEEE 802.16 Convergence Sublayer . . . . . . . . . . . . .  5
   4.  IP over IEEE 802.16 Problem Statement and Goals  . . . . . . .  6
     4.1.  Root Problem . . . . . . . . . . . . . . . . . . . . . . .  6
     4.2.  Point-to-Point Link Model for IP CS: Problems  . . . . . .  8
     4.3.  Ethernet-Like Link Model for Ethernet CS: Problems . . . .  9
     4.4.  IP over IEEE 802.16 Goals  . . . . . . . . . . . . . . . . 10
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11
   6.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 11
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 11
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 12
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 12
1. Introduction
1. 介绍

Broadband Wireless Access networks address the inadequacies of low bandwidth wireless communication for user requirements such as high quality data/voice service, fast mobility, wide coverage, etc. The IEEE 802.16 Working Group on Broadband Wireless Access Standards develops standards and recommended practices to support the development and deployment of broadband Wireless Metropolitan Area Networks [IEEE802.16].

宽带无线接入网络解决了低带宽无线通信在满足用户需求方面的不足,如高质量数据/语音服务、快速移动、宽覆盖、,IEEE 802.16宽带无线接入标准工作组制定标准和推荐做法,以支持宽带无线城域网的开发和部署[IEEE802.16]。

Recently the WiMAX Forum, and in particular, its NWG (Network Working Group) is defining the IEEE 802.16 network architecture (e.g., IPv4, IPv6, Mobility, Interworking with different networks, AAA, etc.). The NWG is thus taking on work at layers above those defined by the IEEE 802 standards (typically limited to the physical and link-layers only). Similarly, WiBro (Wireless Broadband), a Korean effort, which focuses on the 2.3 GHz spectrum band, is also based on the IEEE 802.16 specification [IEEE802.16].

最近,WiMAX论坛,特别是其NWG(网络工作组)正在定义IEEE 802.16网络体系结构(例如,IPv4、IPv6、移动性、与不同网络的互通、AAA等)。因此,NWG在IEEE 802标准定义的层之上承担工作(通常仅限于物理层和链路层)。类似地,韩国致力于2.3 GHz频段的WiBro(无线宽带)也基于IEEE 802.16规范[IEEE802.16]。

IEEE 802.16 [IEEE802.16] is point-to-point and connection-oriented at the MAC, physically arranged in a point-to-multipoint structure with the Base Station (BS) terminating one end of each connection and an individual Subscriber Station (SS) terminating the other end of each connection. The IEEE 802.16 convergence sublayer (CS) is at the uppermost part of the MAC that is responsible for assigning transmit-direction Service Data Units (originating from a higher layer application, e.g., IP or Ethernet at the BS or SS) to a specific outbound transport connection. IEEE 802.16 defines two convergence sublayer types, the ATM Convergence Sublayer (CS) and the Packet CS. The IP Specific Subpart (IP CS) and the 802.3 Ethernet Specific Subpart (Ethernet CS) of Packet CS are within the current scope of IETF efforts.

IEEE 802.16[IEEE802.16]是面向MAC的点对点和连接,物理上以点对多点结构排列,基站(BS)终止每个连接的一端,单个用户站(SS)终止每个连接的另一端。IEEE 802.16汇聚子层(CS)位于MAC的最上层,负责将传输方向服务数据单元(源自更高层的应用程序,例如,BS或SS处的IP或以太网)分配给特定的出站传输连接。IEEE 802.16定义了两种汇聚子层类型,ATM汇聚子层(CS)和分组CS。分组CS的IP特定子部分(IP CS)和802.3以太网特定子部分(以太网CS)在IETF的当前工作范围内。

There is complexity in configuring the IP Subnet over IEEE 802.16 network because of its point-to-point connection-oriented feature and the existence of IP CS and Ethernet CS, which assume different higher-layer functionality. An IP Subnet is a topological area that uses the same IP address prefix where that prefix is not further subdivided except into individual addresses as specified in [RFC4903]. The IP Subnet configuration is dependent on the underlying link-layer's characteristic and decides the overall IP operation on the network. The IP CS and Ethernet CS of IEEE 802.16 assume different higher layer capabilities: IP routing functionality in the case of IP CS and bridging functionality in the case of Ethernet CS. This means that the link-layer's characteristics beneath IP can change according to the adopted convergence sublayers.

在IEEE 802.16网络上配置IP子网存在复杂性,因为它具有面向点对点连接的功能,并且存在IP CS和以太网CS,它们承担不同的高层功能。IP子网是一个拓扑区域,使用相同的IP地址前缀,除[RFC4903]中规定的单个地址外,该前缀未进一步细分。IP子网配置取决于底层链路层的特性,并决定网络上的总体IP操作。IEEE 802.16的IP CS和以太网CS采用不同的高层功能:IP CS的IP路由功能和以太网CS的桥接功能。这意味着IP下链路层的特性可以根据所采用的汇聚子层而改变。

This document provides the feasible IP Subnet model for each IP CS and Ethernet CS and specifies the problems in running IP for each case. This document also presents an overview of IEEE 802.16 network characteristics specifically focusing on the convergence sublayers and the common terminology to be used for the base guideline while defining solution frameworks.

本文档为每个IP CS和以太网CS提供了可行的IP子网模型,并详细说明了在每种情况下运行IP的问题。本文档还概述了IEEE 802.16网络特性,特别侧重于在定义解决方案框架时用于基本指南的汇聚子层和通用术语。

2. Terminology
2. 术语

Subscriber Station (SS): An end-user equipment that provides connectivity to the IEEE 802.16 networks. It can be either fixed/ nomadic or mobile equipment. In mobile environment, SS represents the Mobile Subscriber Station (MS) introduced in [IEEE802.16e].

用户站(SS):提供与IEEE 802.16网络连接的最终用户设备。它可以是固定/游牧或移动设备。在移动环境中,SS代表[IEEE802.16e]中引入的移动用户站(MS)。

Base Station (BS): A generalized equipment set that provides connectivity, management, and control between the subscriber station and the IEEE 802.16 networks.

基站(BS):在用户站和IEEE 802.16网络之间提供连接、管理和控制的通用设备集。

Access Router (AR): An entity that performs an IP routing function to provide IP connectivity for the subscriber station (SS or MS).


Protocol Data Unit (PDU): This refers to the data format passed from the lower edge of the MAC to the PHY, which typically contains SDU data after fragmentation/packing, encryption, etc.


Service Data Unit (SDU): This refers to the data format passed to the upper edge of the MAC


IP Subnet: Topological area that uses the same IP address prefix where that prefix is not further subdivided except into individual addresses as specified from [RFC4903].


Link: Topological area bounded by routers, which decrement the IPv4 TTL or IPv6 Hop Limit when forwarding the packet as specified from [RFC4903].

链路:由路由器限定的拓扑区域,当按照[RFC4903]的规定转发数据包时,路由器会减少IPv4 TTL或IPv6跃点限制。

Transport Connection: The MAC layer connection in IEEE 802.16 between an SS (MS) and BS with a specific Quality of Service (QoS) attributes. Several types of connections are defined and these include broadcast, unicast, and multicast. Each transport connection is uniquely identified by a 16-bit connection identifier (CID). A transport connection is a unique connection intended for user traffic. The scope of the transport connection is between the SS (MS) and the BS.

传输连接:IEEE 802.16中具有特定服务质量(QoS)属性的SS(MS)和BS之间的MAC层连接。定义了几种类型的连接,包括广播、单播和多播。每个传输连接由16位连接标识符(CID)唯一标识。传输连接是用于用户通信的唯一连接。传输连接的范围在SS(MS)和BS之间。

Connection Identifier (CID): A 16-bit value that identifies a connection to equivalent peers in the IEEE 802.16 MAC of the SS (MS) and BS.

连接标识符(CID):一个16位值,用于标识与SS(MS)和BS的IEEE 802.16 MAC中等效对等方的连接。

Ethernet CS: The 802.3/Ethernet CS specific part of the Packet CS defined in [IEEE802.16].

Ethernet CS:在[IEEE802.16]中定义的数据包CS的802.3/Ethernet CS特定部分。

802.1Q CS: The 802.1Q (VLAN) specific part of the Packet CS defined in [IEEE802.16].

802.1Q CS:在[IEEE802.16]中定义的数据包CS的802.1Q(VLAN)特定部分。

IP CS: The IP specific subpart of the Packet CS defined in [IEEE802.16].

IP CS:[IEEE802.16]中定义的数据包CS的IP特定子部分。

IPv4 CS: The IP specific subpart of the Packet CS, Classifier 1 (Packet, IPv4)

IPv4 CS:数据包CS的IP特定子部分,分类器1(数据包,IPv4)

IPv6 CS: The IP specific subpart of the Packet CS, Classifier 2 (Packet, IPv6).

IPv6 CS:数据包CS的IP特定子部分,分类器2(数据包,IPv6)。

3. Overview of the IEEE 802.16 MAC Layer
3. IEEE 802.16 MAC层概述

IEEE 802.16 [IEEE802.16] is point-to-point and connection-oriented at the MAC, physically arranged in a point-to-multipoint structure with the BS terminating one end of each connection and an individual SS terminating the other end of each connection. Each SS in the network possesses a 48-bit MAC address. The BS possesses a 48-bit unique identifier called "BSId". The BS and SS learn each others' MAC Address/BSId during the SS's entry into the network. Additionally, the BS may possess a 48-bit MAC address, but this is only known to the SS if using the Ethernet CS.

IEEE 802.16[IEEE802.16]是面向MAC的点对点和连接,物理上以点对多点结构排列,其中BS端接每个连接的一端,单个SS端接每个连接的另一端。网络中的每个SS都有一个48位MAC地址。BS拥有一个称为“BSId”的48位唯一标识符。在SS进入网络期间,BS和SS相互学习对方的MAC地址/BSId。此外,BS可能拥有48位MAC地址,但这仅在使用以太网CS时为SS所知。

3.1. Transport Connections
3.1. 运输连接

User data traffic in both the BS-bound (uplink) and SS-bound (downlink) directions is carried on unidirectional "transport connections". Each transport connection has a particular set of associated parameters indicating characteristics such as cryptographic suite and quality of service.


After successful entry of an SS to the IEEE 802.16 network, no data traffic is possible as there are no transport connections between the BS and the SS yet. Transport connections are established by a 3-message signaling sequence within the MAC layer (usually initiated by the BS).

在SS成功进入IEEE 802.16网络后,由于BS和SS之间还没有传输连接,因此不可能有数据通信。传输连接由MAC层内的3消息信令序列建立(通常由BS发起)。

A downlink-direction transport connection is regarded as "multicast" if it has been made available (via MAC signaling) to more than one SS. Uplink-direction connections are always unicast.


3.2. IEEE 802.16 PDU Format
3.2. IEEE 802.16 PDU格式

An IEEE 802.16 PDU (i.e., the format that is transmitted over the airlink) consists of a Generic MAC header, various optional subheaders, and a data payload.

IEEE 802.16 PDU(即通过airlink传输的格式)由通用MAC头、各种可选子头和数据有效载荷组成。

The IEEE 802.16 Generic MAC header carries the Connection Identifier (CID) of the connection with which the PDU is associated. We should observe that there is no source or destination address present in the raw IEEE 802.16 MAC header.

IEEE 802.16通用MAC报头携带与PDU关联的连接的连接标识符(CID)。我们应该注意到,原始IEEE 802.16 MAC报头中没有源地址或目标地址。

3.3. IEEE 802.16 Convergence Sublayer
3.3. IEEE 802.16收敛子层

The IEEE 802.16 convergence sublayer (CS) is the component of the MAC that is responsible for mapping between the MAC service and the internal connection oriented service of the MAC CPS (Common Part Sublayer), through classification and encapsulation. The classification process assigns transmit-direction Service Data Units (originating from a higher layer application, e.g., an IP stack at the BS or SS) to a specific outbound transport connection. The convergence sublayer maintains an ordered "classifier table". Each entry in the classifier table includes a classifier and a target CID. A classifier, in turn, consists of a conjunction of one or more subclassifiers -- where each subclassifier specifies a packet field (e.g., the destination MAC address in an Ethernet frame, or the Type of Service (TOS) field of an IP datagram contained in an Ethernet frame) together with a particular value or range of values for the field. To perform classification on an outbound Service Data Unit, the convergence sublayer proceeds from the first entry of the classifier table to the last, and evaluates the fields of the Service Data Unit for a match with the table entry's classifier. When a match is found, the convergence sublayer associates the Service Data Unit with the target CID (for eventual transmission), and the remainder of the IEEE 802.16 MAC and PHY processing can take place.

IEEE 802.16汇聚子层(CS)是MAC的组件,负责通过分类和封装在MAC服务和MAC CP(公共部分子层)的内部面向连接的服务之间进行映射。分类过程将传输方向服务数据单元(源自更高层的应用程序,例如BS或SS处的IP堆栈)分配给特定的出站传输连接。收敛子层维护一个有序的“分类器表”。分类器表中的每个条目包括分类器和目标CID。而分类器又由一个或多个子分类器组成,其中每个子分类器指定一个数据包字段(例如,以太网帧中的目标MAC地址,或以太网帧中包含的IP数据报的服务类型(TOS)字段)以及该字段的特定值或值范围。为了对出站服务数据单元执行分类,汇聚子层从分类器表的第一个条目继续到最后一个条目,并评估服务数据单元的字段是否与表条目的分类器匹配。当找到匹配时,汇聚子层将服务数据单元与目标CID相关联(用于最终传输),并且可以进行IEEE 802.16 MAC和PHY处理的其余部分。

IEEE 802.16 defines two convergence sublayer types, the ATM CS and the Packet CS. The ATM CS supports ATM directly. The Packet CS is subdivided into three specific subparts.

IEEE 802.16定义了两种汇聚子层类型,ATM CS和分组CS。atmcs直接支持ATM。分组CS被细分为三个特定子部分。

o "The IP Specific Subpart" carries IP packets over a point-to-point connection.

o “IP特定子部分”通过点对点连接承载IP数据包。

o "The 802.3 Ethernet Specific Subpart" carries packets encoded in the 802.3/Ethernet packet format with 802.3 style headers.

o “802.3以太网特定子部分”携带802.3/以太网数据包格式编码的数据包,带有802.3样式的报头。

o "The 802.1Q VLAN Specific Subpart" carries 802 style packets that contain 802.1Q VLAN Tags.

o “802.1Q VLAN特定子部分”包含包含802.1Q VLAN标记的802样式数据包。

Classifiers applied to connections at the time of connection establishment further classify and subdivide the nature of the traffic over a connection.


The classifications that apply to the Ethernet CS include packet over the 802.3/Ethernet CS, IPv4 over the 802.3/Ethernet CS, IPv6 over the 802.3/Ethernet CS, 802.3/Ethernet CS with RObust Header Compression (ROHC) header compression and 802.3/Ethernet with Enhanced Compressed Real-Time Protocol (ECRTP) header compression.


The classifications that apply to the 802.1Q/VLAN CS include IPv4 over 802.1Q/VLAN and IPv6 over 802.1Q/VLAN.

适用于802.1Q/VLAN CS的分类包括基于802.1Q/VLAN的IPv4和基于802.1Q/VLAN的IPv6。

It should be noted that while the 802.3/Ethernet CS has a packet classification that does not restrict the IP version (packet over the 802.3/Ethernet CS), the IP CS and 802.1Q/VLAN CS do. All the IP classifiers for those CSs are either IPv4 or IPv6.

应该注意的是,虽然802.3/Ethernet CS具有不限制IP版本(802.3/Ethernet CS上的数据包)的数据包分类,但IP CS和802.1Q/VLAN CS具有限制IP版本的功能。这些CSs的所有IP分类器都是IPv4或IPv6。

The classifiers enable the MAC to be sure of the presence of fields in the headers and so to be able to apply the payload header suppression (PHS) feature of IEEE 802.16 to those headers.

分类器使MAC能够确保报头中存在字段,从而能够将IEEE 802.16的有效负载报头抑制(PHS)功能应用于这些报头。

For the sake of brevity in this document, the following naming conventions will be used for particular classifications of particular subparts of particular CSs.


o IPv4 CS: Packet CS, IP Specific Subpart, Classifier 1 (Packet, IPv4)

o IPv4 CS:数据包CS,IP特定子部分,分类器1(数据包,IPv4)

o IPv6 CS: Packet CS, IP Specific Subpart, Classifier 2 (Packet, IPv6)

o IPv6 CS:数据包CS,IP特定子部分,分类器2(数据包,IPv6)

o Ethernet CS: Packet CS, 802.3/Ethernet Subpart, Classifier 3 (Packet, 802.3/Ethernet)

o 以太网CS:分组CS,802.3/以太网子部分,分类器3(分组,802.3/以太网)

An implementation of IEEE 802.16 can support multiple CS types.

IEEE 802.16的实现可以支持多种CS类型。

We can observe that the CS type, subpart, and classification actually defines the type of data interface (e.g., IPv4/IPv6 or 802.3) that is presented by IEEE 802.16 to the higher layer application.

我们可以观察到,CS类型、子部分和分类实际上定义了IEEE 802.16向更高层应用程序提供的数据接口类型(例如IPv4/IPv6或802.3)。

4. IP over IEEE 802.16 Problem Statement and Goals
4. IP over IEEE 802.16问题陈述和目标
4.1. Root Problem
4.1. 根本问题

The key issue when deploying IP over IEEE 802.16 networks is how to configure an IP Subnet over that link, which is connection-oriented and point-to-point in the MAC level. IP Subnet is a topological area

在IEEE 802.16网络上部署IP时的关键问题是如何在该链路上配置IP子网,该链路在MAC层面向连接且点对点。IP子网是一个拓扑区域

that uses the same IP address prefix where that prefix is not further subdivided except into individual addresses. [RFC4903] There are three different IP Subnet models [RFC4968] that are possible for IEEE 802.16 network:

它使用相同的IP地址前缀,而该前缀除了被细分为单独的地址之外,没有进一步细分。[RFC4903]IEEE 802.16网络可能有三种不同的IP子网模型[RFC4968]:

1) Point-to-point Link Model

1) 点对点链接模型

2) Ethernet-like Link Model

2) 类以太网链路模型

3) Shared IPv6 Prefix Link Model

3) 共享IPv6前缀链路模型

The specific problems and issues when adopting the above IP Subnet models to the IEEE 802.16 network are as below:

在IEEE 802.16网络中采用上述IP子网模型时的具体问题如下:

In the point-to-point link model, each SS under a BS resides on a different IP Subnet. Therefore, only a certain SS and an AR exist under an IP Subnet, and IP packets with destination address of link local scope are delivered only within the point-to-point link between a SS and an AR. PPP [RFC1661] has been widely used for this kind of point-to-point link. However, the direct use of PPP is not possible on the IEEE 802.16 network because IEEE 802.16 does not define a convergence sublayer, which can encapsulate and decapsulate PPP frames. Therefore, there needs to be a mechanism to provide a point-to-point link between an SS and an AR in case of IP CS. The other alternative is to utilize PPP over Ethernet by using the Ethernet CS. However, Ethernet CS assumes the upper layer's bridging functionality to realize the Ethernet-like link model.

在点到点链路模型中,BS下的每个SS位于不同的IP子网中。因此,在IP子网下只存在某个SS和AR,且目标地址为链路本地范围的IP数据包仅在SS和AR之间的点到点链路内传送。PPP[RFC1661]已广泛用于这种点到点链路。但是,在IEEE 802.16网络上不可能直接使用PPP,因为IEEE 802.16未定义可封装和解封PPP帧的聚合子层。因此,在IP-CS的情况下,需要有一种机制来提供SS和AR之间的点对点链路。另一种选择是通过使用以太网CS通过以太网利用PPP。然而,Ethernet CS采用上层的桥接功能来实现类似以太网的链路模型。

In the Ethernet-like link model, all SSs under an AR reside on the same IP Subnet. This also applies when SSs are connected with different BSs. This Ethernet-like link model assumes that underlying link-layer provides the equivalent functionality like Ethernet, for example, native broadcast and multicast. It seems feasible to apply IEEE 802.16's Ethernet CS to configure this link model. However, IEEE 802.16's MAC feature is still connection-oriented, and does not provide multicast and broadcast connection for IP packet transfer. Therefore, we need a mechanism like IEEE 802.1D to realize multicast and broadcast. Moreover, frequent IP multicast and broadcast signaling should be avoided so as not to wake up the SSs that are in sleep/idle mode [IEEE802.16e].

在类似以太网的链路模型中,AR下的所有SSs都位于同一IP子网中。这也适用于SSs与不同BSs连接的情况。这种类似以太网的链路模型假设底层链路层提供类似以太网的等效功能,例如本机广播和多播。应用IEEE 802.16的以太网CS来配置此链路模型似乎是可行的。然而,IEEE 802.16的MAC特性仍然是面向连接的,并且不为IP数据包传输提供多播和广播连接。因此,我们需要一种类似ieee802.1D的机制来实现多播和广播。此外,应避免频繁的IP多播和广播信令,以免唤醒处于睡眠/空闲模式的SSs[IEEE802.16e]。

The shared IPv6 prefix link model eventually results in multi-link subnet problems [RFC4903]. In IEEE 802.16, the BS assigns separate IEEE 802.16 connections for SSs. Therefore, SSs are placed on different links. In this situation, distributing shared IPv6 prefix for SSs, which are placed on different links causes multi-link subnet

共享IPv6前缀链路模型最终导致多链路子网问题[RFC4903]。在IEEE 802.16中,BS为SSs分配单独的IEEE 802.16连接。因此,SSs被放置在不同的链路上。在这种情况下,为放置在不同链路上的SSs分配共享IPv6前缀会导致多链路子网

problems. This applies to IP CS and even to Ethernet CS if no bridging functionality is implemented on top of the BS or between the BS and the AR.

问题。这适用于IP CS,甚至适用于以太网CS,如果在BS顶部或BS与AR之间未实现桥接功能。

We identified the feasible IP Subnet models for IEEE 802.16 networks depending on the convergence sublayers. At the current stage, only the IP CS and Ethernet CS of IEEE 802.16 are within the scope of ongoing IETF work. Following are the feasible IP Subnet models for each convergence sublayer used.

我们根据收敛子层确定了IEEE 802.16网络的可行IP子网模型。在当前阶段,只有IEEE 802.16的IP CS和以太网CS在IETF正在进行的工作范围内。以下是所使用的每个聚合子层的可行IP子网模型。

1. Point-to-Point Link model for IP CS.

1. IP CS的点对点链路模型。

2. Ethernet-like Link Model for Ethernet CS.

2. 以太网CS的类以太网链路模型。

According to the point-to-point feature of the IEEE 802.16 MAC, the Point-to-Point link model is the feasible IP Subnet model in the case of IP CS. For the Ethernet CS, the Ethernet-like link model is the feasible IP Subnet model. However, in this model unnecessary multicast and broadcast packets within an IP Subnet should be minimized.


4.2. Point-to-Point Link Model for IP CS: Problems
4.2. IP-CS的点对点链路模型:问题

- Address Resolution:

- 地址决议:

Address Resolution is the process by which IP nodes determine the link-layer address of a destination node on the same IP Subnet given only the destination's IP address. In the case of IP CS, the IEEE 802.16 MAC address is not used as part of the IEEE 802.16 frame so typical usage of the Address Resolution Protocol (ARP) or Neighbor cache does not apply. Thus, performing the address resolution may be redundant in the case of IP CS. For IPv4, ARP cannot be carried by the IP CS, so is not used either by the SS or by the BS. For IPv6, address resolution is the function of IP layer, and IP reachability state is maintained through neighbor discovery packets. Therefore, blocking neighbor discovery packets would break the neighbor unreachability detection model.

地址解析是指IP节点仅在给定目标IP地址的情况下,确定同一IP子网上目标节点的链路层地址的过程。在IP CS的情况下,IEEE 802.16 MAC地址不作为IEEE 802.16帧的一部分使用,因此地址解析协议(ARP)或邻居缓存的典型用法不适用。因此,在IP-CS的情况下,执行地址解析可能是冗余的。对于IPv4,IP CS无法承载ARP,因此SS或BS都不使用ARP。对于IPv6,地址解析是IP层的功能,IP可达性状态通过邻居发现包来维持。因此,阻塞邻居发现数据包将破坏邻居不可达性检测模型。

- Router Discovery:

- 路由器发现:

The BS needs to send the Router Advertisement (RA) with separate IP prefix in unicast manner for each SS explicitly to send periodic router advertisements in IEEE 802.16 Networks.

BS需要以单播方式为每个SS发送具有单独IP前缀的路由器广告(RA),以便在IEEE 802.16网络中显式地发送周期性路由器广告。

- Prefix Assignment:

- 前缀分配:

Separate IP prefix should be distributed for each SS to locate them on different IP Subnets. When an SS moves between BSs under the same AR, the AR needs to redistribute the same IP Subnet prefix, which the SS used at the previous BS.


- Next-Hop:

- 下一跳:

SS's next-hop always needs to be the AR that provides the IP connectivity at that access network.


- Neighbor Unreachability Detection (NUD):

- 邻居不可达性检测(NUD):

Because the SS always sees an AR as the next hop, the NUD is required only for that AR. Also the requirement of NUD may depend on the existence of a connection to the BS for that particular destination.


- Address Autoconfiguration:

- 地址自动配置:

Because a unique prefix is assigned to each SS, the IP Subnet consists of only one SS and an AR. Therefore, duplicate address detection (DAD) is trivial.


4.3. Ethernet-Like Link Model for Ethernet CS: Problems
4.3. 以太网CS的类以太网链路模型:问题

- Address Resolution:

- 地址决议:

For Ethernet CS, the sender needs to perform an address resolution to fill the destination Ethernet address field even though that address is not used for transmitting an IEEE 802.16 frame on the air. That Ethernet destination address is used for a BS or bridge to decide where to forward that Ethernet frame after decapsulating the IEEE 802.16 frame. When the destination's IP address has the same address prefix with its own, the sender should set the Ethernet frame's destination address as the destination itself. To acquire that address, the address resolution should be performed throughout conventional broadcast- and multicast-based ARP or Neighbor Discovery Protocol (NDP). However, if not filtered (e.g., [RFC4541]), these multicast and broadcast packets result in the problem of waking up the SSs that are in sleep/idle mode [IEEE802.16e].

对于以太网CS,发送方需要执行地址解析以填充目标以太网地址字段,即使该地址未用于在空中传输IEEE 802.16帧。该以太网目标地址用于BS或网桥,以决定在解除IEEE 802.16帧的封装后转发该以太网帧的位置。当目标IP地址与其自身地址前缀相同时,发送方应将以太网帧的目标地址设置为目标本身。要获取该地址,地址解析应该在传统的基于广播和多播的ARP或邻居发现协议(NDP)中执行。然而,如果没有过滤(例如,[RFC4541]),这些多播和广播分组将导致唤醒处于睡眠/空闲模式[IEEE802.16e]的SSs的问题。

- Router Discovery:

- 路由器发现:

All SSs under the AR are located in the same broadcast domain in the Ethernet-like link model. In this environment, sending periodic Router Advertisements with the destination of all-nodes multicast


address results in the problem of waking up the SSs that are in sleep/idle mode [IEEE802.16e].


- Prefix Assignment:

- 前缀分配:

Because the same IP prefix is shared with multiple SSs, an IP Subnet consists of multiple SSs and an AR. The SS assumes that there exist on-link neighbors and tries to resolve the L2 address for the on-link prefixes. However, direct communication using link-layer address between two SSs is not possible with Ethernet CS alone; bridging functionality must be added on top of the BS or between the BS and AR.


- Next-Hop:

- 下一跳:

When Ethernet CS is used and the accompanying Ethernet capability emulation is implemented, the next-hop for the destination IP with the same global prefix with the sender or link local address type should be the destination itself not an AR.

当使用Ethernet CS并实施伴随的Ethernet功能仿真时,具有与发送方或链路本地地址类型相同的全局前缀的目标IP的下一跳应该是目标本身,而不是AR。

- Neighbor Unreachability Detection (NUD):

- 邻居不可达性检测(NUD):

All SSs under the same AR are all the neighbors. Therefore, the NUD is required for all the SSs and AR.


- Address Autoconfiguration:

- 地址自动配置:

Duplicate Address Detection (DAD) should be performed among multiple SSs and an AR, which use the same IP prefix. The previous multicast-based DAD causes the problem of waking up the SSs that are in sleep/ idle mode [IEEE802.16e].


4.4. IP over IEEE 802.16 Goals
4.4. IP over IEEE 802.16目标

The following are the goals in no particular order that point at relevant work to be done in IETF.


Goal #1. Define the way to provide the point-to-point link model for IP CS.

目标#1。定义为IP CS提供点到点链路模型的方法。

Goal #2. Reduce the power consumption caused by waking up sleep/idle [IEEE802.16e] terminals for Ethernet-like link model.


Goal #3. Avoid multi-link subnet problems.


Goal #4. Allow applicability of security schemes such as SEcure Neighbor Discovery (SEND) [RFC3971].


Goal #5. Do not introduce any new security threats.


Goal #6. Review management requirements and specifically the interfaces and specific management model (objects) for IP over IEEE 802.16 in collaboration with IEEE 802.16 working group.

目标6。与IEEE 802.16工作组合作,审查管理要求,特别是IEEE 802.16上IP的接口和特定管理模型(对象)。

5. Security Considerations
5. 安全考虑

This documents describes the problem statement and goals for IP over IEEE 802.16 networks and does not introduce any new security threats. The IEEE 802.16 link-layer employs cryptographic security mechanisms as specified in [IEEE802.16][IEEE802.16e].

本文档描述了IP over IEEE 802.16网络的问题陈述和目标,没有引入任何新的安全威胁。IEEE 802.16链路层采用[IEEE802.16][IEEE802.16e]中规定的加密安全机制。

6. Contributors
6. 贡献者

This document is a joint effort of the problem statement team of the IETF 16ng Working Group. The team members include Junghoon Jee, Syam Madanapalli, Jeff Mandin, Gabriel Montenegro, Soohong Daniel Park, and Maximilian Riegel.

本文件是IETF 16ng工作组问题陈述小组的共同努力。团队成员包括Jee Junghoon、Syam Madanapalli、Jeff Mandin、Gabriel Montegon、Soohong Daniel Park和Maximilian Riegel。

The problem statement team members can be reached at:


Junghoon Jee,


Syam Madanapalli,


Jeff Mandin,


Gabriel Montenegro,


Soohong Daniel Park,


Maximilian Riegel,


7. Acknowledgments
7. 致谢

The authors would like to express special thank to David Johnston for his help with Section 3, "Overview of the IEEE 802.16 MAC Layer", and for carefully reviewing the entire document, and also to Phil Roberts for suggesting the reorganization of the document depending on the baseline IP subnet models.

作者特别感谢David Johnston在第3节“IEEE 802.16 MAC层概述”中提供的帮助,感谢他仔细审阅了整个文档,并感谢Phil Roberts根据基线IP子网模型建议对文档进行重组。

The authors also would like to thank Jari Arkko, HeeYoung Jung, Myung-Ki Shin, Eun-Kyoung Paik, Jaesun Cha, and the KWISF (Korea Wireless Internet Standardization Forum) for their comments and contributions.

作者还要感谢Jari Arkko、HeeYoung Jung、Myung Ki Shin、Eun Kyong Paik、Jaesun Cha和KWISF(韩国无线互联网标准化论坛)的评论和贡献。

8. References
8. 工具书类
8.1. Normative References
8.1. 规范性引用文件

[RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51, RFC 1661, July 1994.


[RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005.

[RFC3971]Arkko,J.,Kempf,J.,Zill,B.,和P.Nikander,“安全邻居发现(SEND)”,RFC 39712005年3月。

8.2. Informative References
8.2. 资料性引用

[IEEE802.16] IEEE Std 802.16-2004, "IEEE Standard for Local and metropolitan area networks, Part 16: Air Interface for Fixed Broadband Wireless Access Systems", October 2004.


[IEEE802.16e] IEEE Std 802.16e, "IEEE standard for Local and metropolitan area networks, Part 16:Air Interface for fixed and Mobile broadband wireless access systems", October 2005.


[RFC4541] Christensen, M., Kimball, K., and F. Solensky, "Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping Switches", RFC 4541, May 2006.

[RFC4541]Christensen,M.,Kimball,K.,和F.Solensky,“互联网组管理协议(IGMP)和多播侦听器发现(MLD)窥探交换机的注意事项”,RFC 4541,2006年5月。

[RFC4903] Thaler, D., "Multi-Link Subnet Issues", RFC 4903, June 2007.

[RFC4903]Thaler,D.,“多链路子网问题”,RFC 49032007年6月。

[RFC4968] Madanapalli, S., "Analysis of IPv6 Link Models for 802.16 Based Networks", RFC 4968, August 2007.

[RFC4968]Madanapalli,S.,“基于802.16网络的IPv6链路模型分析”,RFC 4968,2007年8月。

Authors' Addresses


Junghoon Jee (editor) ETRI 161 Gajeong-dong Yuseong-gu Daejeon 305-700 Korea

Jee Junghoon(编辑)ETRI 161 Gajeong dong Yuseong gu Daejeon 305-700韩国

   Phone: +82 42 860 5126
   Phone: +82 42 860 5126

Syam Madanapalli Ordyn Technologies 1st Floor, Creator Building, ITPL Bangalore - 560066 India

印度班加罗尔ITPL创造者大厦1楼Syam Madanapalli Ordyn Technologies-560066


Jeff Mandin Runcom



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