江苏电信NGN承载网体系结构探索.ppt

1、NGN承载网体系结构探索,华为技术有限公司 战略与Marketing未来网络研究部 李国平,2,一、对NGN承载网体系结构的思考 二、NGN承载网解决方案（IPTN） 三、国际标准化进展,3,第一部分 对NGN承载网体系结构的思考,4,网络控制架构的演变,Traditional Network Control Model,IN, AIN, & Camel,Switch Fabric,Call Control,Bearer Path Control,IN Services,Analog Circuit Wireless,IP/MPLS Domain,Session Control Plane D

2、omain (Softswitch,CSCF),App Servers,App Servers,App Servers,SIP,Diameter,Analog Circuit Wireless,SIP Endpoints,NGN Network Control Model,基于设备的解决方案,基于网络的解决方案,不成熟，发展中,5,对通信网控制体系的分类,通信网控制三对象：路由、链路资源（Link Resource）、会话（Session） 路由的控制模式：静态生成、动态生成；分布路由控制、集中式路由模式 链路资源的控制模式有：分布式、集中式；动态资源控制、静态资源控制 Internet网络只

3、控制路由，所以简单 PSTN、ASON同时在一个设备上实现对三个对象的控制 SDH网对三个对象的控制全由网管实现 NGN网络将对这三个对象的控制分布不同的设备上实现,6,对NGN“承载与控制分离”的置疑,软交换和承载层路由器不发生任何联系行得通吗？ 承载与控制分离是要付出代价的 承载与控制不能绝对的分离 可能造成软交换计费精度不及PSTN，很难达到秒级计费,软交换和承载网一定要以某种方式发生联系！,IP/MPLS Domain,Session Control Plane Domain (Softswitch, CSCF),7,3GPP对“承载与控制分离”的考虑,在R5/R6中引入PDF功能实体

4、，将控制层和承载层有机的联系起来,“这就需要IMS（控制平面）和GPRS网络（用户平面）之间的沟通。Go参考点最初就是出于这个目的被定义的。” Nokia专家书,8,ITU-T对“承载与控制分离”的考虑,There is interaction between control plane in service layer and control plane in transport layer. This interaction includes request/modification acceptance/rejection/release/report for resources of

5、service for session-based or non-session based services.,9,为何IP网络不能满足电信的需求？（一）,如果不考虑复杂的商业运营，目前的IP网络提供的随时随地的连通性基本能满足人们的沟通需求 一旦考虑复杂的商业应用环境，Raw IP网络的很多问题就暴露出来了 计费问题（商业网络的基石）： 用户身份如何识别？企业网无需BRAS，电信网需要BRAS 提供差异化业务问题（QoS）： Internet无法按质论价；为提升网络价值，针对不同客户提供不同等级的服务？ 安全问题：(可用性) 提供商业服务的网络老被攻瘫能行吗？IP网络固有设计缺陷,Raw

6、IP和电信网在观念上存在巨大差异,10,为何IP网络不能满足电信的需求？（二）,Internet的设计思想是智能分散在终端，网络是傻瓜，网络不了解用户业务的质量要求 路由器的网络层智能太少，路由器计算出来的路由可能是不可用的，路由器只根据局部信息计算路由 现在因特网是无连接的，如果下一代网是基于IP的是无连接的，无连接归根到底是解决不了QoS的，只能有限范围解决 NGN将采用Internet的技术（IP或IP友好的传送技术）但不是其机理，即不再让网络作为傻瓜把复杂功能推给终端，在资源分配和业务传递方面网络必须是主动的和有智能的，不能象Internet那样靠终端来适应,11,BT对IP技术的深刻

7、反思（一）,下一代网选择何种技术架构？,Convergence does not mean: Only 1 IP layer controlling all services (e.g. GMPLS) Connectionless (CNLS) only (e.g. Internet). Connection Oriented (CO) only (e.g. ATM). Technology Service,Internet,Frame Relay,ATM,SDH,Converged multi-Service network,12,BT对IP技术的深刻反思（二）,三种网络模式,Functio

8、nal Convergence,There are 3 networking modes that all technologies map into: CNLS e.g. IP, Ethernet. CO Packet Switch e.g. FR, ATM, MPLS. CO Circuit Switch (for bulk transport) e.g. SDH, PDH, OTN. We need all 3 modes to deliver all the services required by our customers: It is not a VHS v. Betamax p

9、opularity competition.,CNLS,CO-PS,CO-CS,13,BT对IP技术的深刻反思（三）,为何需要三种网络模式？,CNLS delivers the Internet. CO-CS delivers the raw bandwidth circuits. Noting that: The size of the circuits we want to switch are getting larger. Well cease to circuit switch the smaller bandwidths ( VC4). Packet switching a flo

10、w that is large enough to be circuit switched is expensive. CO-PS fits the role for customers wanting the strong SLGs of circuits but wanting VC4 worth of bandwidth.,Why do we need 3 modes?,14,BT对IP技术的深刻反思（四）,Raw IP能不能解决问题？,The infinite bandwidth all the time solution! With some bandwidth squeezing

11、mechanisms to compensate. Besides misses the point of what a connection is.,Use lots of bandwidth,Try to save a little,Use slightly less than lots of bandwidth,Could CNLS Do It All?,15,BT对IP技术的深刻反思（五）,面向连接对电信网的重要性,The essence of a carriers service. It is what we manage to provide customer isolation

12、& identification. Transparent transport between end points of the network. The basis of performance guarantees on the probability of obtaining reliable transparent transport of information. The basis of end to end monitoring of the integrity of the transparent transport of the information.,Connectio

13、ns,A Connection Is:,16,BT对IP技术的深刻反思（六）,下一代网的技术架构,The “Architecturally Good” IP Friendly Label stacking Variable length frames Y.1711 OAM,MPLS for CO-PS infrastructure,17,BT对IP技术的深刻反思（七）,QoS如何解决？,We need the capability to have both a packet view, and the packets parent connection view, to fully addre

14、ss the QoS, fairness, meaningfulness, charging problem across all types of service. There is a need for both CO-PS & CNLS network operation in order to support both CO & CNLS services The network needs to be able to deliver both to customers as a seamless services carried over a common network capab

15、le of both CO-PS & CNLS network operation CO-PS operation requires bandwidth allocation, routing and admission control to be coordinated to ensure that SLAs are met and to achieve efficient use of bandwidth,Whats the answer to QoS?,电信网需要的不是基于包的QoS机制，而是基于连接的QoS机制,18,BT对IP技术的深刻反思（八）,带外控制是解决安全的唯一出路,Pho

16、ne freakers return if we stick to todays IP architecture! The PSTN learnt the control plane had to be out of band to be secure. The Cisco “packets of death” demonstrated the weakness of todays IP architecture with the control & user planes congruent. Current fixes of layering security on router oper

17、ating systems to protect routers control & management planes are expensive & unsafe. OOB control & management planes are essential for security. Does not require significant protocol modification. Requires change of architecture thinking. Lower cost & safer.,Out of band management & control data pla

18、ne must be independent of all the elements being managed & controlled.,SecurityThere have been more attacks in the last six months than there has been in the last 10 years, Eslambolchi, AT&T.,19,NGN对IP承载网的需求总结,IP承载网必须以某种方式和业务层发生联系 IP承载网必须同时支持COPS和CNLS两种网络模式 基于COPS网络模式构成的承载子网必须有QoS、安全性、可靠性保证 MPLS及其OA

19、M技术在COPS网络模式中将发挥重要作用,20,第二部分 NGN承载网解决方案,21,NGN承载网总体架构,22,骨干网部分的总体架构,23,骨干网方案的主要特点,采用MPLS技术将IP物理网络划分为COPS和CNLS两个子网，COPS子网承载有QoS保证的业务，CNLS承载Internet业务 COPS子网采用MPLS转发技术，同时采用带外控制技术严格保证电信业务的QoS 采用LSP逐段建立和分域分层技术，保证了方案的可扩展性 不改动骨干路由器，可同时承载Internet业务和电信业务,24,骨干网QoS选路过程,25,业务识别及数据平面安全解决方法,端局路由器,输入 处理,流分类表,业务流

20、,RM,IP电信网,查流分 类表,MPLS,漏桶算法,输出 处理,其他 处理,路由 转发,命中 否？,其他 处理,Internet网,IP1,IP2,每个流分类表项代表的是一个连接 查流分类表的过程实际上是判别数据包属于哪个连接的过程,业务识别完全受网络控制,IP端局功能框图,26,接入网总体方案,27,第三部分 国际标准化进展,28,TISPAN：RACS Subsystem,29,TISPAN: RACS Functional Architecture,30,华为在TISPAN RACS的活动,参加2004年9月13日9月17日会议，提交文稿9篇，“WI for Bearer Contro

21、l Requirements” 的建议得到大会批准，邹婷当选为该Work Item的Rapporteur,31,ITU-T SG13: Y.1291,Approved in 05/2004: “An architectural framework for support of Quality of Service (QoS) in packet networks” Describes six QoS approaches: IntServ,DiffServ,MPLS, IPCablecom Dynamic QoS,Centralized and Path-decoupled Resource

22、Control, Priority Promotion Scheme Centralized and Path-decoupled Resource Control: provided by Huawei and China Telecom,32,ITU-T SG13: RACS (1),In drafting stage: “Functional Requirements and Architecture for Resource and Admission Control in Next Generation Networks” Co-Rapporteur and Editor: 刘恩惠 核心思想来自华为,33,ITU-T SG13: RACS (2),Core RACF,Access RACF,Resource Mediation,Application Functions,CPN,Network Access Attachment Functions,Other networks,IBCF,I-BGF,M-PDF,ENF,A-BGF,I-PDF,C-TRCF,A-TRCF,I d,G q,Go,G3,I1,SCPF,C3,X