计算机网络（Internet） 历史，现状与未来 舒炎泰 2009

计算机网络 Transportation service: move objects horse, train, truck, airplane ... Communication network: move information bird, fire, telegraph, telephone, 计算机网络…Internet …

A Taxonomy of Communication Networks Communication networks can be classified based on the way in which the nodes exchange information: Communication Network Switched Communication Network Broadcast Communication Network 广播，电视 Packet-Switched Communication Network Circuit-Switched Communication Network 电话 Datagram Network Virtual Circuit Network Internet

Circuit Switching （电路交换-电话） A node (switch) in a circuit switching network incoming links outgoing links Node

( ( ( ( The example 思考：电话交换对于计算机是否适合？ 通话在 C 到 D (只经过一个本地交换机) 的连接上进行 通话在 A 到 B (经过四个交换机) 的连接上进行 思考：电话交换对于计算机是否适合？ 效率/成本 应用－实时 交换机 中继线 用户线 交换机 中继线 A B ( 交换机 ( 交换机 ( C 用户线 ( D

Timing in Circuit Switching DATA Circuit Establishment Data Transmission Circuit Termination Host 1 Host 2 Node 1 Node 2 processing delay at Node 1 propagation delay between Host 1 and Node 1 propagation delay between Host 2 and Node 1

Computer networks self-development ---- packet switching 报文 1101000110101010110101011100010011010010 假定这个报文较长 不便于传输 在发送端，先把较长的报文划分成较短的、固定长度的数据段。

Computer networks self-development ----packet switching 分组交换网以“分组”(也称 包)作为数据传输单元 依次把各分组发送到接收端（假定接收端在左边）。 数 据 首部 分组 1 数 据 首部 分组 2 数 据 首部 分组 3

Computer networks development ----packet switching 最后，在接收端把收到的数据恢复成为原来的报文。 这里我们假定分组在传输过程中没有出现差错，在转发时也没有被丢弃。 报文 1101000110101010110101011100010011010010 数 据 数 据 数 据

Packet Switching - Example Router E Router C Router A Router D Router Congested Router B Router F

Timing of Datagram Packet Switching Host 1 Host 2 Node 1 Node 2 Packet 1 propagation delay between Host 1 and Node 2 transmission time of Packet 1 at Host 1 Packet 2 Packet 1 Packet 3 processing delay of Packet 1 at Node 2 Packet 2 Packet 1 Packet 2 Packet 3 Packet 3

Packet Switching （分组/包交换） 1961 A node in a packet switching network incoming links outgoing links Node Memory

Model: Queuing System Customers Server Queue Queuing System Use Queuing models to Describe the behavior of queuing systems Evaluate system performance

Response Time vs. Arrivals

Internet 历史(1) Sep69 1st IMP in UCLA, Oct69 2nd IMP in SRI Internet 之父-- L. Kleinrock 1999 1969

History of the Internet (2)

History of the Internet (3) Sep69 1st IMP in UCLA Oct69 2nd IMP in SRI 22:30 29Oct69 LOGIN from UCLA to SRI CLA We sent an “L” - did you get the “L”? YEP! We sent a “O” - did you get the “O”? YEP! We sent an “G” - did you get the “G”? Crash!

Internet Physical Infrastructure

Network Components (Examples) Links Interfaces Switches/routers Ethernet card Fibers Large router Wireless card Coaxial Cable Telephone switch

Growth of the Internet Today: backbones run at 2.4/10/100 Gbps, 500 millions computers in 150 countries

Internet 在中国 1993年3月 中科院高能物理所 64 Kbps TJU:1995.3.22 2008年7月 计算机8470万 用户 2.5亿 WWW站 192万 CN域名 1190万 国际出口带宽 494 Gbps 连接美国、俄罗斯、法国、英国、德国、日本、韩国、新加坡等

趋势: 网络时代 每一件事务都是数字的: 声音, 视频, 音乐, 画片 每一件事务都是在线的: 银行, 医疗, 航空, 天气情况, 公路交通, … 每个人之间都是相互联系的:医生,教师,经济人,母亲,儿子, 朋友, 敌人 实现家庭 教育， 办公， 购物， 娱乐/网上娱乐 虚拟工作场所 2000年，美国有五千五百万人实现远程工作 网络制造/电子商务

趋势: 网络时代

计算机集成制造系统/先进制造/信息化 CIMS (Computer Integrated Manufacturing) 1973 Dr. Joseph Harrington 目标：市场竞争 - T, Q, C, S 时间T（即开发新产品的时间或成熟产品的上市时间）、质量Q、成本C和服务S 核心思想 系统的观点 -- 全局优化 企业的各个环节，包括市场分析、产品设计、加工制造、经营管理及售后服务的全部经营活动，是不可以分割的整体. 信息的观点 -- 信息集成 企业的运行是信息采集，传递，加工处理的过程. 产品可以看作数据的物质表现.

目标-提高竞争力（CIMS-Internet） 70年代前 降低劳动成本 降低产品成本 70年代 提高企业整体效益 降低产品成本 提出CIMS 80年代 TQCS CIMS推广应用 90年代 新产品开发，信息、知识 CIMS发展 2000年代 核心：服务/用户 网络制造/ 电子商务 范围：全球企业间/供应链 资源：信息、知识（无时空）

网络制造 Internet从单纯的信息工具变成”E－时代”的关键资源.全球经济一体化成为制造业变革的最根本的推动力 在相互联结的网络上，建立24小时工作的协同工作组，大大加快了设计进度、及时获得所需要的零部件，减少库存、降低成本，提高质量 网络制造的本质特性就是产品的制造过程更加分散化，信息的传递网络化，信息的流动伴随着各项工作的并发进行而同时发生

电子商务 信息技术和Internet引发的商务过程的变化 利用以Internet为核心的信息技术，进行商务活动和企业资源管理 CIMS是企业实施电子商务的基础 企业实施电子商务是CIMS发展的主要标志和主要内容

电子商务产生背景 竞争环境改变 核心 产品竞争 服务竞争 范围 单个企业 全球多企业 资源 人、财、物 信息、知识 管理重心迁移 生产管理 核心 产品竞争 服务竞争 范围 单个企业 全球多企业 资源 人、财、物 信息、知识 管理重心迁移 生产管理 供应/营销链管理 集中内部资源 整合外部资源 离散管理 集约管理

商务模式转化 传统商务 电子商务 文秘型管理 关注后台（企业内部） 关注业务记录（报表） 地区性 推销产品为中心 （卖方市场） 自我服务型管理 关注前端（客户关系） 要求商业智能（分析） 全球化 客户为中心 （买方市场）

e企业的业务体系结构 客户 产品/服务 销售 服务/支持 市场营销 产品制造 供应商 合作伙伴 网络智能

协同产品商务( CPC) 用户在互联网上参与产品的开发、设计及修订。 在虚拟市场空间中，顾客与生产者及供应商一起参与产品生命周期中的每一项技术及商业环节。 不受地域及时间的限制，信息可以快速地流动。

企业的发展趋势 网络制造--电子商务 部门之间的障碍 业务流程 2000年以后 电子商务工程 企业之间的障碍 业务过 程重组 业务过 程重组 IDS Sheer 部门之间的障碍 业务流程 2000年以后 电子商务工程 IDS Sheer 企业之间的障碍 网络制造--电子商务

网络发展趋势 趋势: 融合 趋势: 泛在（Ubiquitous） 趋势: 信息爆炸 更多的网络业务流量 数据流量 > 话声流量 更快的传输介质/骨干网（Backbone） 更大的带宽（Bandwidth） 宽带无线网飞速增长(WLAN) (Wi-Fi) Everything over IP

趋势: 融合 新闻/广告-媒体-信息提供者 数字媒体产品 有线电视 视频传输 电话 声音传输 计算机 数字媒体存储/处理 信息提供者和信息传输者的结合 电话公司, 有线公司, 娱乐事业, 和计算机公司的结合

Trend:

Why Optical Networks? DWDM optoelectricl metro network

Trend:宽带无线网飞速增长

Trend: Wireless / Mobile

Future Internet Research and Experimentation

Today’s Internet Millions of users Web, email, low-quality audio & video Interconnect personal computers and servers Applications adapt to underlying technology Today’s Internet Doesn’t Provide reliable end-to-end performance Encourage cooperation on new capabilities Allow testing of new technologies Support development of revolutionary applications Since commercialization in 1994, key characteristics of the Internet have changed: the size of the network and the capacity applications require support beyond the original design parameters of the underlying technologies.

Since commercialization in 1994, key characteristics of the Internet have changed: the size of the network and the capacity applications require support beyond the original design parameters of the underlying technologies.

Internet2 Project Develop and deploy advanced network applications and technologies, accelerating the creation of tomorrow’s Internet. Goals Enable new generation of applications Re-create leading edge R&E network capability Transfer capability to the global production Internet 206 University Members, Jan. 2005

Abilene Connections: July 2006 Abilene Connections :: Apr-2000

Abilene International Peering 2006 Abilene Connections :: Apr-2000

Internet Development Spiral Commercialization Privatization Today’s Internet This spiral represents one way of looking at the development of the Internet. As the Internet moved from a research project to a commercial service, a set of partnerships fostered its development. During this process, the Internet grew in a number of ways: size, complexity, bandwidth, etc. Internet2 is forming the partnerships needed for technologies in a second cycle of innovation make their way into the commercial Internet. Internet2 Research and Development Partnerships

Advanced applications com in many flavors, and those flavors can be combined. Advanced applications share the characteristic that they require advanced network capabilities to work—they either don’t work at all, or won’t work well on today’s Internet. Enabling advanced applications is at the heart of Internet2.

Packet-Switching vs. Circuit-Switching Most important advantage of packet-switching over circuit switching: ability to exploit statistical multiplexing: Efficient bandwidth usage; ratio between peek and average rate is 3:1 for audio, and 15:1 for data traffic However, packet-switching needs to deal with congestion: More complex routers Harder to provide good network services (e.g., delay and bandwidth guarantees) In practice they are combined: IP over SONET, IP over Frame Relay

Virtual-Circuit Packet Switching Hybrid of circuit switching and packet switching Data is transmitted as packets All packets from one packet stream are sent along a pre-established path ( = virtual circuit) Guarantees in-sequence delivery of packets However: Packets from different virtual circuits may be interleaved Example: ATM networks MPLS?

Virtual-Circuit Packet Switching Host A Host B Host E Host D Host C Node 1 Node 2 Node 3 Node 4 Node 5 Node 6 Node 7

Virtual Circuit Packet Switching-Example 1. Connection Establishment 2. Information Transfer 3. Circuit Disconnect Router E Router C Router A Router D Router B Router F

Timing of Virtual-Circuit Packet Switching Host 1 Host 2 Node 1 Node 2 propagation delay between Host 1 and Node 1 VC establishment Packet 1 Packet 2 Packet 3 Packet 1 Packet 2 Packet 3 Data transfer Packet 1 Packet 2 Packet 3 VC termination

We are at an Impasse ISPs are unlikely candidates for architectural change We can’t test new architectures - Despite sizable investments in testbeds We can’t deploy new architectures - And things are getting worse, not better Yet there are pressing requirements for which the current architecture is not well suited

GENI (Global Environment for Network Innovations) - NSF 2005 (1) What is GENI? GENI is a facility concept being explored by the US computing community back to an NSF workshop in 2005 focus on architectural research, and provide the experimental infrastructure needed to support that research focus on the research agenda (and infrastructure needs) of the optical, wireless, sensor network, and distributed systems communities

GENI (Global Environment for Network Innovations) (2) The goal of GENI Goal: a Future Internet that meets the demands of 21st century to increase the quality and quantity of experimental research outcomes in networking and distributed systems to accelerate the transition of these outcomes into products and services enhance economic competitiveness and secure the Nation's future Ultimately, to lead to a transition of the Internet

FIND (Future Internet Network Design) – NSF 2006 FIND asks two broad questions: What are the requirements for the global network in 15 years How would we re-conceive tomorrow's global network today, if we could design it from scratch? FIND program solicits "clean slate process" research proposals in the broad area of network architecture, principles, and design

FIRE (Future Internet Research and Experimentation) – European 2007 FIRE is an experimentally-driven long-term research initiative on Future Internet concepts, protocols and architectures encompassing technological, industrial and socio-economic aspects acting as proof-of-concept of the newly proposed technologies and services FIRE RESEARCH Long term multidisciplinary research on future internet paradigms Open to fresh bottom-up ideas with no backwards-compatibility constraints Building on the FET SAC initiative “Situated and Autonomic Communications” Considering at the same time technological, economic and social/policy aspects Build in from the outset and on all levels the right balance between security / accountability and privacy