GPON QoS专题介绍-20061225-A

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GPON基础介绍

GPON基础介绍GPON（Gigabit-capable Passive Optical Network）是一种基于光纤传输的宽带接入技术，可以提供高速且稳定的数据传输。

本文将介绍GPON的基础知识及其原理。

GPON是一种面向家庭和企业用户的接入技术，它利用了光纤传输的高带宽和抗干扰能力，可以提供高速的网络连接。

与传统的基于铜线的ADSL或VDSL接入技术相比，GPON可以提供更高的传输速率和更远的传输距离。

GPON采用了一种被动光网络架构，其中光纤在整个网络中起到了关键的作用。

在GPON网络中，光纤被用来传输数据，而不是电信号。

这种纯光传输的方式可以大大降低传输损耗和干扰。

GPON网络由三个主要组件组成：光线传输单元（OLT），光纤接入单元（ONT）和光纤分配器（ODN）。

OLT是GPON网络的核心设备，负责连接用户和服务提供商的网络。

ONT是连接用户设备的终端设备，它将光信号转换为电信号，并提供网络连接给用户。

ODN则是用来将光纤连接到ONT的分配设备。

GPON网络采用了时间分割多路复用（TDM）技术，它将光信号分割为不同的时间片段，每个时间片段用于传输不同的数据流。

这种技术可以使多个用户同时共享一条光纤，并实现有效的带宽利用。

在GPON网络中，数据流被分为两种类型：上行和下行。

上行数据流是从用户设备发送到服务提供商的数据流，而下行数据流是从服务提供商发送到用户设备的数据流。

由于GPON网络采用了不对称传输方式，上行和下行数据流可以拥有不同的传输速率。

GPON网络支持高达2.5Gbps的下行速率和1.25Gbps的上行速率。

这种高速度可以轻松满足多种应用的需求，如高清视频流、在线游戏和云存储等。

此外，GPON网络还支持语音通话和视频监控等实时应用。

GPON网络具有很多优点。

首先，由于光纤具有高带宽和低损耗的属性，GPON网络可以提供稳定且高速的数据传输。

其次，由于采用了纯光传输的方式，GPON网络对电磁干扰具有很强的抵抗能力。

QoS教程详解

14
优先级与队列的映射
COS值的范围0-7，每个值对应一个输出队列优先级与队列的映射
COS
队列 4 4 3 3 2 2 1 1
15
7
6 5 4 3 2 1 0
1:low queue 2:normal queue 3:medium queue 4:high queue
高低优先调度
重要业务要求在拥塞发生时优先获得服务以减小响应延迟在队列调度时，根据高低优先队列之间的轮循比值来转发报
设为16 1.配置一个与TCP端口30000上的数据包匹配的访问列表
access-list 100 permit tcp any any eq 30000
2.使用类别映射表配置一个通信流配置文件 class-map TCP-PORT-30k match access-group 100 exit
26
27

任务五：配置所有的出站队列，将COS值设为4 6 和7的通信流加入队列3中，CoS值5的通信流加入到队列4中
1.同时配置多个接口 int range fa1/1 – 24 2.接口上配置适合的CoS映射关系 wrr-queue cos-map 4 5 wrr-queue cos-map 3 4 6 7 exit
high
按规定的速度向桶中存放令牌
medium
分类
继续发送
须由此接口发送的数据流
normal
令牌桶丢弃
low
12
拥塞管理和队列调度
流分类
high medium normal 输出队列 low

队列机制

高低优先级队列
严格优先级队列加权轮循队列最大时延加权轮循队列

GPON技术介绍

GPON技术介绍GPON技术特征主要体现在传输汇聚层。

GPON协议参考模型如图2所示，其中传输汇聚层又分为PON成帧子层和适配子层。

GTC(GPONTransmissionConvergence)的成帧子层完成GTC帧的封装，终结所要求的ODN的传输功能，PON的特定功能（如测距、带宽分配等）也在PON的成帧子层终结，在适配子层看不到。

GTC的适配子层提供PDU与高层实体的接口。

A TM和GFP信息在各自的适配子层完成SDU与PDU的转换。

OMCI（Operations Management Communications Interface，操作管理通信接口）适配子层高于A TM和GFP适配子层，它识别VPI/VCI和Port_ID，并完成OMCI通道数据与高层实体的交换。

作为一种灵活的吉比特光纤接入网，GPON支持更高的速率和对称/非对称工作方式，同时还有很强的支持多业务和OAM的能力。

它以A TM信元和GFP （GenericFramingProcedure，通用成帧规程）承载多业务，对各种业务类型都能提供相应的QoS保证，支持商业和居民业务的宽带全业务接入。

EPON与GPON技术比较GPON与EPON最主要的区别表现在TC帧结构上。

GPON通过A TM和GFP两种协议承载不同类型的用户数据。

它的上、下行帧长均为125μs。

下行采用TDM方式，上行采用时分多址（TDMA）接入技术。

上行帧由复用的突发传输时隙（slot）组成，每帧包括一个或多个ONU的传输时隙，通过下行帧的USBWmap（上行带宽映射）域指示相应ONU的上行数据发送。

而EPON帧格式基本与IEEE802.3的以太数据帧格式兼容，只在以太帧中加入时标及识别等信息，Ethernet PON数据通过不定长的数据包传输。

GPON在用户净荷数据段承载A TM信元和（或）GFP帧。

在OLT授权给ONU的上行发送时隙中，OLT尽量使分配给ONU的A TM净荷块为53字节的整数倍长，如果净荷不是信元的整数倍，将进行碎片填充。

GPON系统中基于QoS的动态带宽分配算法的研究

中文核心期刊ＧＰＯＮ系统中基于ＱｏＳ的动态带宽分配算法的研究王欣，顾畹仪（北京邮电大学电信工程学院，北京１００８７６）摘要：为了实现吉比特无源光网络（ＧＰＯＮ）带宽分配的公平性，降低网络的丢包率及传输延时，研究了ＧＰＯＮ系统传输汇聚层的帧结构及带宽分配的实现方法，提出了一种新的动态带宽分配（ＤＢＡ）算法———基于ＱｏＳ的二层动态带宽分配算法。

性能分析与对比表明，这种算法对不同用户和不同等级的业务都具有很好的公平性，并可以降低低等级业务的传输延时。

关键词：吉比特无源光网络；光网络单元（ＯＮＵ）；ＱｏＳ中图分类号：ＴＮ９２９．１１文献标志码：Ａ１引言目前，ＩＴＵ－Ｔ已经通过了ＧＰＯＮ的部分标准，包括Ｇ．９８４．１（总体特性）、Ｇ．９８４．２（物理媒质相关层描述）、Ｇ．９８４．３（传输汇聚层描述）和Ｇ．９８４．４（ＯＮＴ管理控制接口规范），ＧＰＯＮ技术正逐步走向成熟。

全业务接入网联盟（ＦＳＡＮ：ＦｕｌｌＳｅｒｖｉｃｅＡｃｃｅｓｓＮｅｔｗｏｒｋ）制定ＧＰＯＮ规范的目的就是支持现有的及未来可能出现的各种不同业务。

虽然ＧＰＯＮ系统的网络体系结构同所有的无源光网络接入系统相同，但它却有着其他接入网所没有的优越特性：◆采用ＧＥＭ封装格式，提高了数据封装的效率，最高可达９７％。

对高层各种不同类型，不同速率的业务进行封装后利用ＰＯＮ透明传输，支持现有的各种语音、数据及视频业务。

◆网络覆盖范围广，各ＯＮＵ之间的物理距离最远可达２０ｋｍ，ＯＮＵ与ＯＬＴ之间的最大逻辑距离可达６０ｋｍ。

◆可支持对称和不对称的多种线路速率，最大支持速率可达２．５Ｇｂ／ｓ，能满足现有及未来可能出现的各种业务对带宽的需要。

２ＧＰＯＮ中ＤＢＡ的实现方法２．１ＧＰＯＮ传输汇聚层的帧结构ＧＰＯＮ的下行帧结构如图１所示。

帧长为１２５ｍｓ。

当下行速率是１．２４４１６Ｇｂ／ｓ时，帧长为１９４４０字节；当下行速率是２．４８８３２Ｇｂ／ｓ时，帧长为３８８８０字节。

GPON技术介绍

GPON技术介绍
GPON（Gigabit Passive Optical Network，千兆无源光网络）是一
种利用千兆无源光网络技术实现“一条线”实现多用户互联的新兴网络技术，是由ITU-T标准Q.1209，OIF实施指南ID-319规定的一种新技术，
受到世界各地电信企业的普遍采纳。

GPON是一种集宽带、多媒体、语音、数据、传输信令的新兴的“一条线”技术，具有良好的经济性、可靠性和
可管理性，使用率高，可以部署先进的多媒体服务。

这一技术的关键在于
它采用千兆无源光网络技术，这种技术可以减少光纤线路上的放大器数量，大大节省网络投资。

GPON是一种综合应用于有线和无线多媒体服务的新兴技术，可以实
现“一条线”发布宽带、多媒体服务，满足用户的多种需求，它采用了新
型的多芯片技术，实现了具有弹性的设备拓扑，包括普通用户、企业用户
等的宽带接入和各种宽带应用，同时确保了宽带服务的质量，为客户和网
络提供良好的使用体验。

GPON由三部分组成：光源，光缆，接收/发射器。

光源采用兼容1609.3标准的二极管激光器，它是一种小功率激光器，可以实现低功耗
状态。

光缆是构成光网络的基础，它可以是多根的单模光缆，也可以是多
芯的多模光缆，有助于改善网络的可靠性，以及容量的提升。

GPON限速及QoS

GPON限速及QoS1限速在上行方向，通过配置ONU-G::Traffic management option来设置流量管理方式为上行流量速率控制（Rate controlled upstream traffic），可以对每个业务最大上行流量进行速率控制。

但这个速率控制是针对每个GEM连接进行管理控制的，而不是针对整个ONT的上行速率进行控制。

在每个代表GEM连接的GEM port network CTP里面，GEM port network CTP::Traffic descriptor profile pointer属性用于指向GEM traffic descriptor，但这个属性仅在ONU-G::Traffic management option设置为速率控制（Rate controlled upstream traffic）时候才被用到。

每个GEM连接的速率控制参数可以通过配置GEM traffic descriptor进行设定，其中GEM traffic descriptor::SIR用于设定该连接的保证速率(sustained information rate)，GEM traffic descriptor::PIR用于设定该连接的峰值速率(peak information rate)。

在下行方向，没有用于设定下行流量速率控制的ME。

2上行QoS在上行方向上，通过配置ONU-G::Traffic management option可以对上行流量的管理方式设定为优先级控制调度（Priority controlled and flexibly scheduled upstream traffic）。

在这种情况下，优先级队列(priority queue)和流量调度器(traffic scheduler)等Qos机制将会用于上行业务流。

图1为上下行业务流的数据流程图。

图1：上下行业务的数据流程图从图1可以看出，上行业务流在到达GEM port network CTP，根据ONU-G::Traffic management option的不同，开始流经不同的途径：若为速率控制方式，则直接被送到T-CONT；若是优先级调度方式，则被送到Priority Queue(up Stream)。

gpon方案

GPON方案概述GPON（Gigabit-capable Passive Optical Network）是一种光纤传输技术，可提供千兆级别的宽带接入服务。

GPON方案集成了光纤传输、光分配、光波转换和网络传输等功能，广泛应用于住宅、企业和校园等网络环境中。

本文将介绍GPON方案的基本原理、特点以及在不同领域应用的情况。

GPON的基本原理GPON基于波分复用技术，使用单根光纤传输多个信号。

GPON系统由三个主要组成部分组成：光线终端（OLT）、光网络单元（ONU）和光纤线路。

GPON使用点对多点的架构，其中OLT通过光纤将高速数据传输到ONU，实现了高速、稳定的宽带接入。

OLT负责将数据转换为适用于光纤传输的格式，并将数据传输到ONU。

ONU则接收并解码数据，将其发送到终端设备。

GPON的特点GPON方案具有以下特点：1.高带宽：GPON方案提供千兆级别的带宽，能够满足用户对高速网络的需求，可支持高清视频、在线游戏和大规模文件传输等应用。

2.长距离传输：GPON光纤的传输距离可达20公里，支持远程接入，适用于广域网部署和大范围覆盖。

3.分布式架构：GPON系统采用分布式架构，光线终端（OLT）和光网络单元（ONU）分别部署在中心节点和用户端，使得网络管理更加灵活和可靠。

4.省电节能：GPON方案采用边缘用户的睡眠模式，有效降低了能量消耗，实现了节能环保。

5.服务质量保证：GPON具备多种服务质量保证机制，可以满足不同用户对网络服务的需求。

6.灵活扩展：GPON系统支持灵活的扩展，可以根据实际需求增加或减少光网络单元（ONU）的数量。

GPON在不同领域的应用GPON方案在各个领域都有广泛的应用，以下是其中一些常见领域：住宅小区网络GPON方案可为住宅小区提供高速、稳定的宽带接入服务。

通过部署一个光线终端（OLT）和多个光网络单元（ONU），可以实现多户共享一个光纤网络，提供统一的网络接入。

这样，住宅小区的居民可以方便地享受高速上网、网络电视和互联网电话等服务。

GPON基础知识

2003年3月，发布GPON 标准G.984.1和G.984.2
2001年底，把APON 更名为BPON
2001年初，开始进行 GPON标准的研究
1995年， FSAN成立
1998年10月，发布APON标准
2011年，发布 NGA1标准
2009年Q1完成NGA PON的技术白皮书，包
括NGA1/2的需求、 NGA1的规范、NGA2的
SC
Subscriber Connector/Standard Connector 推压型，可以很容易地装卸。是最普通的连接器。重量轻，体积小，便于
操作。用于OLT和ONU的PON口。
LC
Lucent Connector / Local Connector 为推压型，可以很容易地装卸。是超小型光连接器，可以进行高密度装配。用于OLT上连接口
EPON：适宜承载基于以太网的业务，简单、低成本、中等性能，满足公众住宅客户需求。
GPON：完善支持多业务接入，复杂性稍高，完备性、性能与安全性较好，可满足综合业务接入需求。
NGA PON与10GEPON的融合
内部公开▲
背景
技术发展的融合标准组织越来越多的合作联盟和制定标准的专家趋于相同
GEM：GPON Encapsulation Method
T-CONT
Transmission Container
内部公开▲
GPON业务流专有名词 - GEM Port
数据流的最小单位，由Port Id来标识。按方向分类：单下行、单上行、双向。按用途分类：业务GEM port，管理GEM port。以太帧按照一定的规则，映射到GEM帧中。
节点
网络

GPON原理和产品介绍

G.984.4——GPON的OMCI要求
– 2004年6月发布最初版， 2008年2月发布更新版，2009年6月和11月分别发布了更新版的修订1和修订2。千兆无源光网络的终端管理与控制接口规范
G.984.5——GPON增强带宽
– 2007年9月发布最初版，未来在G-PON系统中利用WDM技术为新增业务信号提供预留波长，为此定义波长范围，使光分配网ODN的价值最大化
G.984.6 ——GPON距离延伸
– 2008年3月发布最初版，概括了利用物理层距离延伸装置实现距离延伸的GPON 的体系架构和接口参数，最大逻辑距离可达60km
GPON技术基本参数
GPON提供以下几种传输速率： 0.15552 Gbit/s up, 1.24416 Gbit/s down 0.62208 Gbit/s up, 1.24416 Gbit/s down 1.24416 Gbit/s up, 1.24416 Gbit/s down 0.15552 Gbit/s up, 2.48832 Gbit/s down 0.62208 Gbit/s up, 2.48832 Gbit/s down 1.24416 Gbit/s up, 2.48832 Gbit/s down（目前的主流支持速率） 2.48832 Gbit/s up, 2.48832 Gbit/s down 支持最大逻辑距离为：60km 支持最大物理距离为：20km 支持最大距离差为：20km 分光比为1：64，可升级为1：128
下行采用广播方式上行采用TDMA方式
目前的EPON/GPON/10G EPON/XGPON1均属于功率分割型的PON网络，所支持的分支数量和距离主要取决于光功率预算
内部公开▲
GPON的标准和规范(1)

GPON原理及相关产品基础知识

5 bytes
GEM Payload
GPON系统对以太网帧进行解析，将数据部分直接映射到GEM Payload中去进行传输。 GEM帧会自动封装头信息。映射的格式清晰，设备很好实现，兼容性好。
通信工程设计
TDM业务在GPON中的映射方式
TDM
TDM Buffer Ingress buffer
GEPON
APON
GPON
BPON GPON
EPON
通信工程设计
GPON与EPON的比较
标准速率分光比承载带宽效率 QOS
光预算 DBA ONT互通 OAM
P2MP GPON
ITU.T 2.488G/1.244G
1:64~1:128 ATM, Ethernet, TDM
92% Very good， including Ethernet, TDM, ATM Class A/B/C
通信工程设计
GPON的协议栈
物理媒质相关（PMD）层和GPON传输汇聚（GTC）层组成。 GTC层包括两个子层：GTC成帧子层和TC适配子层。 GTC层可分为两种封装模式：ATM模式和GEM模式，目前仅规范GEM模式。 GTC层可为其客户层提供2种类型的接口：GEM客户接口和ONT管理和控制接口
都可以采用PON的方式承载
通信工程设计
什么是PON?
PSTN
Passive Optical Network 无源光网络
Optical Line Terminal
光线路终端
Passive Optical Splitter
无源分光器
ONU ONU
Internet CATV
OLT
Passive Optical Splitter

GPON系统详解

l l l l
Metro Ethernet Forum(MEF)制定的MEF8，在以太网上实现电路仿真； IETF制定的PWE3，在IP网上实现电路仿真； ITU-T制定的Y.1413，在MPLS网络上实现电路仿真； MPLS与帧中继联盟(MFA)制定的MFA 8.0.0，在MPLS网络上实现电路仿真；
秘密▲
ONU上行单播业务模型 - 2
秘密▲
ONU上行单播业务模型 - 3
1 2 3
GEM Port U/S Priority Queue 1
4
5
GEM Port ETH UNI 802.1p Mapper GEM Port
U/S Priority Queue 2
Traffic Scheduler
GPON系统详解
王国梁固网上海软件开发一部 2009年1月
内容提要
GPON基础知识回顾 ONU探秘 ODN关键点 OLT线卡 OLT主控板 OLT上联板
内部公开▲
GPON基础知识回顾 – 初识GPON
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GPON是个宽带接入网，由OLT、ODN和ONU组成，树型拓扑结构 OLT：C200、C220、C300 ODN：
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ONU业务模型详解
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单播业务模型组播业务模型广播、洪泛业务模型 VoIP业务模型 TDM业务模型
ONU上行单播业务模型 - 1
秘密▲
n n n n n n
ETH UNI，表示ONT的UNI口。 MAC Bridge，按照VID进行数据流的转发。也可以进行VLAN Tag的处理。 802.1p Mapper，按照P-bit进行数据流的转发。数据流被映射到一个GEM Port中。数据流通过流量调度器（优先级队列或流量整形），被送到相应的T-CONT中。在相应的时隙内，数据被发送给OLT。

三网合一中GPON的QoS保证

Abstract—Recently, in some places, optical-fibre access networks have been used with GPON technology belonging to organizations (in most cases public bodies) that act as neutral operators. These operators simultaneously provide network services to various telecommunications operators that offer integrated voice, data and television services. This situation creates new problems related to quality of service, since the interests of the users are intermingled with the interests of the operators. In this paper, we analyse this problem and consider solutions that make it possible to provide guaranteed quality of service for voice over IP, data services and interactive digital television.Keywords—GPON networks, multioperator, quality of service, triple-play services.I.I NTRODUCTIONUBLIC networks with shared access are being developed in order to cover areas where it is not profitable for commercial operators to provide service.In January 2003, the ITU approved Recommendation G.984.1/2/3, commonly known as GPON (Gigabit Passive Optical Network) [2]. This recommendation, which was based on work of the Full-Service Access Network (FSAN) working group, made it possible for PON networks to operate at up to 2,488 Mbps and support the ATM and TDM Ethernet protocols.At the same time, the IEEE 802.3ah Ethernet in the First Mile (EFM) task force developed standards for EPON (Ethernet over PON) networks [4].While standard GPON allows both asymmetric and symmetric configurations, EPON only allows the latter. The binary configurations of GPON are maintained in the configurations established for the Synchronous Digital Hierarchy (SDH) [3], but EPON configurations are aligned with the Gigabit Ethernet standard.Additionally, while standard GPON allows three split ratios (1:16, 1:32 or 1:64), EPON only allows the first two. Both GPON and EPON allow Reed-Solomon Forward Error This work was supported in part by the EuQoS project (6FP-004503), the Spanish Ministry of Education and Science (MEC) under the CEPS project (TSI2005-07520-C03-02) and CONTENT Network of Excellence (2-IST-NoE-0384239) .Germán Santos-Boada and Jordi Domingo-Pascual are with the Department of Computer Architecture, Technical University of Catalonia, C/ Jordi Girona Salgado 1-3, 08034 Barcelona, Spain (phone: +34934016981; fax: +34934017055; e-mail: german@ and jordid@). Correction (FEC), but they use different line codes: Non-Return to Zero (NRZ) for GPON and 8B/10B for EPON. [10] The Ethernet-native protocol presents certain limitations (it has no reserve capacity and therefore does not guarantee the delay, etc.). Ethernet over Multiprotocol Label Switching (EoMPLS) technology promises to correct this.In the upstream direction, EPON bandwidth efficiency can be as low as 61% for Ethernet traffic, which means that just 730 Mbits/sec of actual bandwidth is available for Ethernet packet transport. In contrast, GPON bandwidth efficiency is around 93% or approximately 1,160 Mbits/sec. In the downstream direction, EPON efficiency is 73%, with 875 Mbits/sec of bandwidth for Ethernet packet transport. GPON efficiency is 94% or 2,250 Mbits/sec. This efficiency, combined with a higher line rate, gives GPON a significant advantage, especially for service providers looking to deliver high-bandwidth services like IPTV [1].The GPON standard is therefore being applied in the development of access networks of this type.GPONs take advantage of wavelength-division multiplexing (WDM). They use one wavelength for downstream traffic and another for upstream traffic. This allows for two-way traffic on a single optical fibre. The latest specification calls for downstream traffic to be transmitted on the 1,490 nm wavelength and upstream traffic to be transmitted at 1,310 nm. The 1,550 nm band is purposely left open in case the service provider wishes to share the PON fibre with a Hybrid Fibre-Coaxial (HFC) network, which is the traditional cable TV architecture. Traditional operators of HFC systems can also use shared GPON networks.II.GPON Q UALITY OF S ERVICEThe GPON standard guarantees quality of service using the MAC protocol, which controls concentration and multiplexing by assigning slots of variable length for each user and service [7].By themselves, higher bandwidth and greater efficiency in Ethernet transport cannot ensure the delivery of high-quality voice, data and video across a GPON network.It is necessary to distinguish between different services by classifying traffic flows with IP DiffServ Code Points (DSCPs). Priorities must also be set in Ethernet traffic (IEEE 802.1p) and police functions and queues must be used to prioritize traffic [1].The GPON Encapsulation Method (GEM), with identification of ports, makes it possible to separate up toQuality of Service in Multioperator GPONAccess Networks with Triple-Play ServicesGermán Santos-Boada, and Jordi Domingo-PascualPeight different types of traffic at the entrance and exit of the network. Thus, traffic can be queued according to service.The average-access system used by GPON networks prevents collisions. The GEM protocol, which allows the multiplexing of traffic, is used for this purpose. GEM packets, which allow the payload to be fragmented, can transport as much Ethernet traffic as TDM allows. The upstream resource-allocation algorithm is based on a polling system, although the exact implementation has not been standardized by FSAN. The generated traffic is distributed among various queues with different priorities based on Ethernet Bridging (IEEE 802.1q). In order to ensure the minimum delays, backbone access bridges/routers must be non-blocking and the traffic aggregation must be based on Virtual Private LAN Service (VPLS). This guarantees the identification of traffic by means of IEEE 802.1p-bit and/or DSCP marks, which act as the gateway to a IP/MPLS network.This is important in a conventional GPON network. However, it is even more important in a multioperator network, where priorities are set not only among services but also among operators and network customers. Network commercial operators and neutral providers typically enter into a contractual agreement called an SLA (Service Level Agreement), which specifies the ability of a network or protocol to give guaranteed performance, throughput or latency bounds based on mutually agreed measures, usually by prioritising traffic.III. M ULTIOPERATOR N ETWORK M ODELThe model analysed in this paper is based on a GPON network shared by several operators and managed by a neutraloperator. The network consists of a generic router thatprovides access to the wired networks, data IP networks,interactive digital television networks, and analog and digital(DTT) television broadcasting distribution networks of each operator that shares the network.Fig. 1 GPON multioperator network architectureFrom this router, in the direction of the user, the equipment is connected via a Gigabit Ethernet (GbE) connection to the Optical Line Termination (OLT), which is where the proper GPON network begins (see Fig. 1). The OLT executes GEM and manages the quality of service offered by the network. With an integrated splitter, the OLT can have up to 32 optical fibres, each of which provides service to a splitter cabinet nearthe end user with up to 8 optical fibres, which connect to the Optical Network Termination (ONT), also known as the Optical Unit Network (ONU), which is the final device to which each user connects. [9]The structure of the network allows up to 1,024 users for each OLT.The network can also have a system for transporting the signals of HFC operators by transmitting video RF along the fibres of the GPON network. As a result, HFC networks do not influence the quality of service of a network. Therefore, some networks will offer HFC networks.The end user connects to the ONT for triple-play service using the 10/100BaseT interface for data/internet and video IP and using the RJ11 interface for POTS.A. Level 2 ProtocolsThe traffic that circulates through a GPON network is Ethernet traffic. This traffic is the payload of the MAC network protocol, based on GEM, which makes it possible to define the GPON framing and the MAC control fields and contains all the necessary elements to define the Medium-Access Control concept. The queue status reporting, the slots and the treatment of the various classes of traffic are defined in the MAC using a mechanism of the Gigabit Ethernet (GbE) connection: round-robin polling. The traffic flows are handled based on priority and operation is based on connection by means of Alloc-Id identification.The OLT manages access and distributes priorities at the MAC level using the GEM protocol. The GEM headercontains the following fields (see Fig. 2): a payload length indicator (PLI), used for delineation; a Port ID, which allowsmultiplexing of flows; a payload type indicator (PTI), whichshows whether the fragment contains user data or OAM andwhether it is the last fragment of a user frame; and a HECfield, for error detection and correction as well as delineation [7].Fig. 2 GEM encapsulationLevel 2 traffic—Ethernet traffic between the OLT and the router, encapsulated by GEM—allows us to identify the user, operator and service. This is done using QinQ Ethernet labels. Thus, label 1 identifies the user and label 2 defines the operator and the service. The connection between the router and the network of each operator is also level 2 Gigabit Ethernet traffic. Label 3 of 802.1Q is used to identify the user and the service. Between the router and the OLT, there is a VLAN VLL for each user/service.B. Triple-Play Quality of ServiceInternet traffic generally consists of access to websites, e-mail, file transfer, peer-to-peer and other forms of data transfer. At level 2, either PPP over Ethernet or the DynamicOper. 1RF GatewayV5.2Oper. 2Oper. N(data)OLT RouterSplitterHost Configuration Protocol (DHCP) can be used.With voice IP traffic, the end user can use the H.248 protocol with the RJ11 interface in order to cross the V5.2 gateway and access the public operator telecommunications system (POTS).The user can also use the RJ45 interface and H323/SIP protocol with transparent transport to cross the GPON network to the softswitch that is connected to the POTS by means of the H.248 protocol [11].The system used depends on the type of operator: an incumbent operator with a developed POTS network or an incoming operator with an IP-based telephone network.Baseline video traffic can be actual video streams or video emulated through the use of scripts. Both unicast for video-on-demand and multicast for broadcast services over UDP are required.The transport of video over IP is based on IP multicast. The following elements are recommended: DVB-IPI with the MPEG-2 and MPEG-4 (HDTV) coding systems (digital TV) and the IGMP, HTML, and RTSP (video on demand).In terms of types of traffic, different general circumstances may occur with triple-play service. Different types of isolated or combined traffic can be created. We will consider their performance in terms of latency, data loss and throughput.In order to ensure that the traffic flows provide the proper quality of service and to implement police functions, we must measure the availability of prioritization of streams in a triple-play environment. Several quality-of-service parameters must be applied to quantify throughput and response times for different traffic combinations. Internet traffic is given the lowest priority, since data services are not drastically affected by packet delays. Video traffic has the next highest priority, since a minimum loss of video packets does not negatively affect the perceived appearance, as long as the streaming audio track is not broken. Finally, voice over IP will have the highest priority, since voice services are very sensitive to latency and loss of packets [12].IV.P ROBLEMS WITH M ULTIOPERATOR Q UALITY OF S ERVICE In a GPON network like the one proposed in this paper, quality of service is guaranteed for each service and end user. Priorities are therefore set in accordance with this scheme and the GEM management procedure does not consider any another options.In our case, however, the network is multioperator. The prioritization criteria need to take this fact into account. An end user may have more than one voice-over-IP line contracted through an operator. For data, an operator may offer its clients different access speeds and in some cases provide committed information rates (CIRs). As for video, operators can offer their clients simultaneous television with different channels or different video-on-demand sessions.This range of possibilities cannot be generalized by all operators that share a GPON. Each operator’s range of possibilities will depend on its IP backbone and video-server capacity. Quality of service is allocated based on priority queuing and bandwidth allocation by user in accordance with GEM. Downstream traffic is multiplexed using Time-Division Multiplex (TDM) and upstream traffic is multiplexed using Time-Division Multiple Access (TDMA), in accordance with the MAC protocol. This protocol manages user bandwidth by controlling police functions. The MAC protocol is therefore vitally important to controlling traffic and guaranteeing quality of service.The GPON Encapsulation Method (GEM) is a protocol like MAC that was developed in GPON and makes it possible to transmit Ethernet frames and TDM and ATM cells using 125-microsecond fixed-size time slots. Therefore, the Ethernet frames may be fragmented [4].In the header, the downstream frames contain the upstream bandwidth map with the allocations of all upstream frames. The MAC allocations indicate the length, time, queue and user for each frame. Due to traffic fluctuations, dynamic bandwidth allocation (DBA) is used. This system defines the BW for each frame [5] [8].In summary, at the physical level the information is divided based on time. The encapsulated Ethernet frames are sent in the time slots using the GEM protocol, which has medium-access mechanisms and allocates the required bandwidth. This traffic is served to the network according to the service-based priorities: voice, then television and finally data. The GEM manager controls medium access in the OLT by assigning upstream and downstream slots to each terminal and service using the DBA algorithm. Each ONT can assign bandwidth using a round-robin polling procedure.FSAN specifies five different types of traffic known as T-CONT [4]. These definitions are related to throughput and delay. The DBA algorithm makes it possible for the MAC controller of the OLT to create an image of the queuing situation for each type of traffic in the whole GPON network, thus enabling an effective allocation of throughput and control of delay [7].Taking into account the above considerations, we deduce that the problem of quality of service in GPON multioperating networks is centered in which service offers the network adapted for each operator, knowing that already it offers it for each type of traffic and terminal.V.M ULTIOPERATOR P OLLING T ABLEIn a single-operator GPON access network, the MAC controller in the OLT manages the various services provided by assigning different priorities. In a multioperator GPON network, because each operator offers its own services, we must make some changes to the MAC controller.We propose two simple modifications to manage this latter case. The first is to increase the number of priorities that are managed for each service. The second is to modify the polling table in order to consider the multioperator case and avoid unfairness.A.PrioritiesThe previous sections have shown that priority is given to voice services, followed by TV services and finally by data services. Because each operator may offer more than onevoice, TV and data service (for instance, with different CIRs), we need different priority levels for the overall set of services. In multioperator environments, each operator must be able to offer multiple voice channels, television channels and CIRs for data. The quality of service provided by the network must be based on this possibility [13]. We propose modifying the number of priorities following two different approaches. First, a different type of priority should be considered for each service (see Table I). We propose allowing up to four services because this is generally the maximum number of television sets per home, and four voice lines and CIRs is sufficient.TABLE IFor each ONT, each operator will define a certain priority for each service and will enter into an SLA with the network. If an ONT has two voice channels, one may have priority 1 and the other may have priority 4, or both may have priority 1. Three television channels can be seen simultaneously: two with priority 2 and one with priority 5. The priority is based on the service, not the user.Second, if all the possible variations of the three services (see Fig. 3) are considered, then each user has a unique priority (broad, not service-based). The star in the figure indicates a user’s priority with three televisions on, one voice line on, and data being transmitted with the third available CIR.In this case, there are 64 different priorities.VoiceDataFig. 3 Broad prioritiesThe neutral operator can choose the first or second priority table, as required by the SLA, and the order of priorities.B.PollingThe polling table must be developed not only to maintain the quality-of-service parameters for each ONT, but also to satisfy the demands of the various operators that share the network (see Table II).We propose a table that takes into account the number of ONTs per operator. Therefore, access is distributed and slots are allocated based on the number of users per operator. The regular, priority-based Dynamic Bandwidth Allocation (DBA) algorithms are applied.RR indicates the execution of the round-robin process. Its value represents the polling sequence.TABLE IIIn order to guarantee the SLA for each service and maintain fairness among services and operators, polling slots must be assigned to each operator based on the distribution shown below. Within an operator, regular round-robin polling is applied in the ONT.If we consider N operators sharing a GPON access network and each operator has ONT i users, then the total number of ONTs isONT t = ∑NiONT iThen, for each polling cycle, each operator will have RR slots, beingRR = ONT i / ONT tThis simple modification of the polling cycle guarantees both quality of service and fairness.VI.C ONCLUSIONProbably the development of GPON networks will be generalized. However, in places where this service is not commercially profitable, public organizations with social aims may act as neutral operators by renting their networks to commercial operators that offer triple-play services. We have considered a new quality-of-service which must be satisfied not only for each type of service but also for each operator.In this work, we propose solutions for aspects that can be modified in all quality-of-service processes in a multioperator network, while maintaining all quality-of-service procedures established by G.984 for GPON and the standardized medium-access and bandwidth-management methods. Having analysed all the mechanisms (standardized and otherwise) for guaranteeing quality of service in GPON, we conclude that the two aspects that change when a network has multiple operators are the establishment of priorities and the management of the medium-access method (polling). Wepropose solutions that make it possible to guarantee SLAs for operators and maintain the proper quality of service.R EFERENCES[1]S. Rashid. “Beyond Bandwidth: QoS and Service Differentiation inGPON.” . 2006.[2]ITU-T/G.984.1 “Gigabit-Capable Passive Optical Networks (GPON):General Characteristics”.[3]ITU-T/G.984.2 “Gigabit-Capable Passive Optical Networks (GPON):Physical Media Dependent (PMD) Layer Specification”.[4]ITU-T/G.984.3 “Gigabit-Capable Passive Optical Networks (GPON):Transmission Convergence Layer Specification”.[5]ITU-T/G.984.4 “A Broadband Optical Access System with IncreasedService Capability Using Dynamic Bandwidth Assignment”.[6]IEEE 802.3ah “Ethernet in the First Mile Task Force, Point toMultipoint Ethernet on SM Fiber (PON)”.[7]John D. Angeloupoulos, Helen-C. Leligou, Theodore Argyriou andStelios Zontos. “Efficient Transport of Packets with QoS in an FSAN-Aligned GPON”. IEEE Communications Magazine, February 2004, pp.92-98.[8]J. Jiang, M.R. Handley and J.M. Senior. “Dynamic BandwidthAssignment MAC Protocol for Differentiated Services over GPON”.Electronics Letters, Volume 42, Issue 11, 25 May 2006, pp. 653-655. [9]Alcatel White Paper. “Optical Network Design Considerations forPON”. . 2005.[10]Alcatel White Paper. “GPON versus EPON”. . 2005.[11]Alcatel White Paper. “GPON Voice Strategies”. . 2005.[12]ALTERA White Paper. “Traffic Management for Testing Triple-PlayServices”. . March 2006.[13]M. Abrams and A. Maislos. “Insights on Delivering an IP Triple Playover GE-PON and GPON”. Optical Fiber Communications Conference 2006, 5-10 March 2006.。

GPON关键技术介绍

不同的GEMPORT用Port-ID
标识
GPON标识– ONU
● PON用户终端，由ONU Id标识。
● 这里的ONU Id是系统内部使用的，不等于用户配置ONU时使用的索引值； ● 用户在配置ONU时，系统会自动为其分配一个ONU Id； ● 用户配置ONU时使用的索引值，在单个PON口内不能重复；
● 以太帧的帧间隔、前导符、定界符、以及同步BIT被丢弃，载荷部分被复制为GEM的载荷
● GEM帧的头字段
● PLI表示载荷的长度； ● Port-ID通常由以太帧的VLAN TAG映射得到，具体映射规则由用户配置； ● PTI表示GEM帧的类型，如当前的载荷是管理信息，还是业务数据； ● CRC对头字段进行校验；
GPON标识– T-CONT
● 上行带宽调度的最小单位，由Alloc Id来标识。
● 这里的Alloc Id是系统内部使用的，不等于用户配置T-CONT时使用的索引值； ● 用户在配置T-CONT时，系统会自动为其分配一个Alloc Id； ● 用户配置T-CONT时使用的索引值，在单个ONU内不能重复，不同ONU之间可以重复。如在ONU 1下
（O3） ● 测距状态Ranging-state（O4） ● 运行状态 Operation-state（O5） ● POPUP状态POPUP-state（O6） ● 紧急停止状态Emergency-Stop-
state（O7）
GPON系统ONU的发现和测距
● 新ONU发现有两种模式
● 随机竞争，不需要事先在OLT上配置ONU的SN号，采用SN自动学习方式。 ● 序列号MASK模式，需要事先在OLT上配置ONU的SN号。
● ONU的发现和测距分两步
● 获取SN号，要把所有ONU的SN号获得或直到超时才结束该步。 ● 测量新发现ONU的距离，给ONU配置EqD （Equalization Delay）时间。

GPRS Qos说明

QOS1. R97/R98 QoSR97/R98 QoS（3个字节），包括下列参数：Precedence class:优先级Delay class：延迟等级Reliability class：可靠性Peak throughput class：峰值吞吐量Mean throughput class：平均吞吐量2. R99 QoSR99 QoS(11个字节)，保留了原来的3个字节，增加了8个字节，新增如下参数：Traffic Class:业务类型Delivery order:传输顺序Delivery of erroneous SDU:是否传输错误SDUMaximum SDU size: 最大SDU 尺寸Maximum bit rate for uplink :上行最大比特率Maximum bit rate for downlink :下行最大比特率Residual BER:剩余SDU 错误率SDU Error ratio:SDU 错误率Transfer delay: 传输时延Transfer handling priority:传输处理优先级Guaranteed bit rate for unlink:保证的上行最大比特率。

Guaranteed bit rate for downlink:保证的下行最大比特率3. R5/R6 QoSR5/R6 QoS(14个字节)，除了原来11个字节后，又增加了3个字节，新增如下参数：Signalling IndicationSource Statistics DescriptorMaximum bit rate for downlink (extended)Guaranteed bit rate for downlink (extended)4. QoS字段结构QoS IE 结构（information elementcoded）8 7 6 5 4 3 2 1Octet 14Figure 10.5.138/3GPP TS 24.008: Quality of service information element5. Allocation/Retention Priority在Gb/Iu信令中，qos的字节长度如上，但在Gn的信令中，qos中会自动增加1个字节：Allocation/Retention priority。

路由器QOS技术

网络拥塞的产生
流量聚合
100Mbps 100Mbps
Data-flow
民族安全创新服务
网络拥塞的后果
尾丢弃（Tail Drop）：当发生拥塞时，接口输出队列被占满，后面要入队的报文被丢弃。尾丢弃是最普通的丢弃机制，也是系统默认的丢弃机制。对TCP流来讲，尾丢弃有以下缺陷：（1）TCP全局同步；（2）TCP饿死、延迟、抖动
服务模型，是指一组端到端的Qos功能 Best-Effort service 尽力而为服务 Integrated service (Intserv) 集成服务
Differentiated service (Diffserv) 区分服务
民族安全创新服务
Best-Effort service
民族安全创新服务
QOS技术目标

支持为用户提供专用带宽减少报文的丢失率避免和管理网络拥塞流量整形设置报文的优先级
民族安全创新服务
课程内容
1
QOS技术概念 QOS服务模型
网络拥塞的产生和避免拥塞管理技术
2
3 4 5
流量监管与流量整形
民族安全创新服务
QOS服务模型
民族安全创新服务
Differentiated service
Differentiated service 区分服务
Diffserv是一个多服务模型，可以满足不同的Qos维护状态，它根据每个报文指定的QoS，来提供特定的服务，包括进行报文的分类、流量整形、流量监管和排队。主要实现技术包括CAR,队列技术。
router1(config)#interface serial 0/0

GPON QoS专题介绍-20061225-A

方式：将不同优先级的报文入不同的队列，不同队列将得到不同的调度优先级、
概率或带宽保证。
LD
流分类
优先队列金牌服务银牌服务铜牌服务输出队列 LU
算法：
FIFO（ First In First Out ）先进先出 PQ（ Priority Queue ）优先级队列 CQ（ Custom Queue ）定制队列 WFQ（ Weighted Fair Queuing ）加权公平队列
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第1章 QoS概述
1.1 基本概念
1.2 QoS技术
1.3 QoS体现
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QoS体现
NGN Service
• 听得清楚 • 没有回音
IPTV Service
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第2章 GPON中的QoS
1.1 处理机制
1.2 处理流程
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第1章 QoS概述第2章 GPON中的QoS 第3章产品实现和配置
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第1章 QoS概述
1.1 基本概念
1.2 QoS技术
1.3 QoS体现
Internal
GPON QoS专题介绍
ISSUE 1.0

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