计算机网络（ Internet）历史，现状与未来

舒炎泰 舒炎泰 20020099

计算机网络 Transportation service: move objects

horse, train, truck, airplane ... Communication network: move information

bird, fire, telegraph, telephone, 计算机网络计算机网络… Internet …

Communication networks can be classified based on the way in which the nodes exchange information:

A Taxonomy of Communication Networks

Communication Network

SwitchedCommunication

Network

BroadcastCommunication Network

广播，电视Circuit-SwitchedCommunication Network

电话

Packet-SwitchedCommunication Network

Datagram Network

Virtual Circuit Network

Internet

The example 通话在 通话在 C C 到 到 D (D ( 只经过一个本地交换机只经过一个本地交换机 ) ) 的连接上的连接上

进行进行 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

交换机

交换机

交换机用户线

用户线

中继线中继线

B

D

C

A

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

incoming links outgoing linksNode

Circuit Switching: Multiplexing/Demultiplexing

Time divided in frames and frames divided in slots

Relative slot position inside a frame determines which conversation the data belongs to

Needs synchronization between sender and receiver

In case of non-permanent conversations Needs to dynamic bind a slot to a conservation How to do this?

Timing in Circuit Switching

propagation delay between Host 1 and Node 1

propagation delay between Host 2 and Node 1

DATA

Circuit Establishment

Data Transmission

Circuit Termination

Host 1 Host 2Node 1 Node 2

processing delay at Node 1

报文

在发送端，先把较长的报文划分成较短的、固定长度的数据在发送端，先把较长的报文划分成较短的、固定长度的数据段。 段。

1101000110101010110101011100010011010010

假定这个报文较长不便于传输

Packet Switching （分组 / 包交换） 1961

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。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。没有被丢弃。

数 据 数 据 数 据

报文1101000110101010110101011100010011010010

Packet Switching （分组 / 包交换） 1961

Data are sent as formatted bit-sequences, so-called packets

Packets have the following structure:

Header and Trailer carry control information (e.g., destination address, check sum)

Each packet is passed through the network from node to node along some path (Routing)

At each node the entire packet is received, stored briefly, and then forwarded to the next node

(Store-and-Forward Networks) Typically no capacity is allocated for packets

Header Data Trailer

Router Congeste

d

Router A

Router B

Router C

Router D

Router E

Packet Switching - Example

Router F

Timing of Datagram Packet Switching

Packet 3

Packet 3

Packet 1

Packet 2

Packet 1

Packet 2

Packet 1

Packet 2

Packet 3

processing delay of Packet 1 at Node 2

Host 1 Host 2Node 1 Node 2

propagationdelay betweenHost 1 and Node 2

transmission time of Packet 1at Host 1

Packet Switching （分组 / 包交换） 1961 A node in a packet switching networkA node in a packet switching network

incoming links outgoing linksNode

Memory

Packet Switching: Multiplexing/Demultiplexing

Data from any conversation can be transmitted at any given time

How to tell them apart? Use meta-data (header) to describe data

Datagram Packet Switching Each packet is independently switched

Each packet header contains destination address No resources are pre-allocated (reserved) in advance Example: IP networks

Use Queuing models to Use Queuing models to Describe the behavior of queuing systemsDescribe the behavior of queuing systems Evaluate system performanceEvaluate system performance

Model: Queuing System

Queuing System

Queue Server

Customers

Response Time vs. Arrivals

1W

Waiting vs. Utilization

0

0.05

0.1

0.15

0.2

0.25

0 0.2 0.4 0.6 0.8 1 1.2

W(s

ec)

Internet 历史 (1) Sep69 1st IMP in UCLA, Oct69 2nd IMP in SRI

Internet 之父 -- L. Kleinrock1999 1969

History of the Internet (2)

History of the Internet (3)

Sep69 1st IMP in UCLA Sep69 1st IMP in UCLA Oct69 2nd IMP in SRI Oct69 2nd IMP in SRI

22:30 29Oct6922:30 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 提供的服务 Shared access to computing resources

telnet (1970’s) Shared access to data / files

FTP, NFS, AFS (1980’s) Communication medium over which people interact

email (1980’s), on-line chat / messaging (1990’s) audio, video (1990’s)

replacing telephone network? A medium for information dissemination

USENET (1980’s) WWW (1990’s)

replacing newspaper, magazine? audio, video (1990’s)

replacing radio, CD, TV?

Internet Physical Infrastructure

Classification by Coverage

模型 , 协议 , 分层

Protocol Architecture

Don’t Need All Layers Everywhere

Protocol Data Unit - PDUs

Network Components (Examples)

Fibers

Coaxial Cable

Links Interfaces Switches/routers

Ethernet card

Wireless card

Large router

Telephoneswitch

Growth of the Internet Today: backbones run at 2.4/10/100 Gbps, Today: backbones run at 2.4/10/100 Gbps, 500 millions computers in 150 countries500 millions computers in 150 countries

中科院高能物理所中科院高能物理所 19931993 年年 33 月月 64Kbps64Kbps 1986.8.25 Email1986.8.25 Email

TJU:1995TJU:1995 年年 33 月月 2222 日日 20092009 年年 77 月月

网民 网民 3.43.4 亿 亿 WWWWWW 站 站 306306 万万 CNCN 域名 域名 12961296 万万 国际出口带宽 国际出口带宽 748 Gbps748 Gbps

连接美国、俄罗斯、法国、英国、德国、连接美国、俄罗斯、法国、英国、德国、日本、韩国、新加坡等日本、韩国、新加坡等

宽带接入速度远远落后于发达国家宽带接入速度远远落后于发达国家

Internet 在中国

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 1973 Dr. Joseph Harrington Dr. Joseph Harrington 目标：市场竞争 目标：市场竞争 - - T, Q, C, ST, Q, C, S

时间时间 TT （（即开发新产品的时间或成熟产品的上市时间）即开发新产品的时间或成熟产品的上市时间）、质量、质量 QQ 、、成本成本 CC 和服务和服务 S S

核心思想核心思想 系统的观点 系统的观点 -- -- 全局优化全局优化

企业的各个环节企业的各个环节，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，是不是不可以分割的整体可以分割的整体 ..

信息信息的观点 的观点 -- -- 信息信息集成集成 企业的运行是企业的运行是信息信息采集，传递，加工采集，传递，加工处理的过程的过程 . .

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 / 用户范围：全球企业间 / 供应链资源：信息、知识（无时空）

网络制造网络制造 /电子商务

网络制造 InternetInternet从单纯的信息工具变成”从单纯的信息工具变成” EE－时代－时代

”的关键资源”的关键资源 ..全球经济一体化成为制造业变全球经济一体化成为制造业变革的最根本的推动力革的最根本的推动力

基于基于 InternetInternet 的虚拟制造与虚拟装配的虚拟制造与虚拟装配 在相互联结的网络上，建立在相互联结的网络上，建立 2424 小时工作的协小时工作的协同工作组，大大加快了设计进度、及时获得所同工作组，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，提高质需要的零部件，减少库存、降低成本，提高质量量

网络制造的本质特性就是产品的制造过程更加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

竞争环境改变 核心 产品竞争

电子商务产生背景

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

•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）

传统商务 电子商务

客户

供应商

合作伙伴

网络智能

市场营销 产品 /服务销售 产品制造

服务 /支持

e 企业的业务体系结构

协同产品商务 ( CPC)

用户在互联网上用户在互联网上参与产品的开发参与产品的开发、设计及修订。、设计及修订。

在虚拟市场空间在虚拟市场空间中，顾客与生产中，顾客与生产者及供应商一起者及供应商一起参与产品生命周参与产品生命周期中的每一项技期中的每一项技术及商业环节。术及商业环节。

不受地域及时间不受地域及时间的限制，信息可的限制，信息可以快速地流动。以快速地流动。

制造规划方案制造规划方案 生产管理方案生产管理方案 销售和输送方案销售和输送方案

维护和售后服务方案维护和售后服务方案

营销方案营销方案 产品开发方案产品开发方案

零部件管理方案零部件管理方案

供应商方案供应商方案

制造规划方案制造规划方案 生产管理方案生产管理方案 销售和输送方案销售和输送方案

维护和售后服务方案维护和售后服务方案

营销方案营销方案 产品开发方案产品开发方案

零部件管理方案零部件管理方案

供应商方案供应商方案

Internet/Intranet

制造企业 用户 供应商 ……

企业的发展趋势

部门之间的障碍

业务过 程重组 IDS Sheer

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 趋势趋势 : : 融合融合 趋势趋势 : : 泛在（泛在（ UbiquitousUbiquitous ）） 趋势趋势 : : 信息爆炸信息爆炸 更多的网络业务流量更多的网络业务流量 数据流量 数据流量 > > 话声流量话声流量 更快的传输介质更快的传输介质 //骨干网（骨干网（ BackboneBackbone）） 更大的带宽（更大的带宽（ BandwidthBandwidth）） 宽带无线网宽带无线网飞速增长飞速增长 (WLAN) (Wi-Fi)(WLAN) (Wi-Fi) Everything over IPEverything over IP

趋势 : 融合 新闻新闻 // 广告广告 --媒体媒体 -- 信息提供者信息提供者

数字媒体产品数字媒体产品 有线电视有线电视

视频传输视频传输 电话电话

声音传输声音传输 计算机计算机

数字媒体存储数字媒体存储 //处理处理 信息提供者和信息传输者的结合信息提供者和信息传输者的结合 电话公司电话公司 , , 有线公司有线公司 , , 娱乐事业娱乐事业 , , 和计算机公司和计算机公司

的结合的结合

Trend:

趋势 : 更快的传输介质 局局域域网：网： 1 Gbps over 4-pair UTP-5 up to 100 m, 1 Gbps over 4-pair UTP-5 up to 100 m,

10Gbps being discussed10Gbps being discussed Was 1 Mbps (1Base-5) in 1984Was 1 Mbps (1Base-5) in 1984

骨干网：光纤骨干网：光纤 DWDMDWDM (( Dense Wavelength Dense Wavelength Division Multiplexing)Division Multiplexing) OC-768 = 40 Gbps over a to 65 km, OC-768 = 40 Gbps over a to 65 km,

1600 Gbps - 10 Tbps1600 Gbps - 10 Tbps Was 100 Mbps (FDDI) in 1993Was 100 Mbps (FDDI) in 1993

无线网：无线网： 54 /500 Mbps(100-2km-50km) wireless 54 /500 Mbps(100-2km-50km) wireless networks, 2.5 Gbps to 5km using light networks, 2.5 Gbps to 5km using light Was 1 Mbps (IEEE 802.11) in 1998Was 1 Mbps (IEEE 802.11) in 1998

Why Optical Networks? DWDM optoelectricl metro network

Trend:宽带无线网飞速增长

Trend:宽带无线网 (Wi-Fi)飞速增长

Trend: Wireless / Mobile

Integration of 3G and WLAN- offer possibility of achieving anywhere, anytime,

high speed and low expense Internet access

3G3G WLANWLAN

Wide areaWide area Local areaLocal area

Low bit rate Low bit rate

(2M when stand (2M when stand still)still)

High bit rateHigh bit rate

(11M to 54M)(11M to 54M)

Data/Voice serviceData/Voice service

((QoS supportQoS support))

Data serviceData service

High expenseHigh expense Low expenseLow expense

High mobilityHigh mobility Low mobilityLow mobility

Future Internet Research and Experimentation

Today’s Internet Millions of usersMillions of users Web, email, low-quality audio & videoWeb, email, low-quality audio & video Interconnect personal computers and serversInterconnect personal computers and servers Applications adapt to underlying technologyApplications adapt to underlying technology Today’s Internet Doesn’tToday’s Internet Doesn’t

Provide Provide reliablereliable end-to-end performance end-to-end performanceEncourage cooperation on new capabilitiesEncourage cooperation on new capabilitiesAllow testing of Allow testing of new technologiesnew technologiesSupport development of revolutionary Support development of revolutionary applicationsapplications

Internet2 Project Develop and deploy advanced network Develop and deploy advanced network

applications and technologies, accelerating applications and technologies, accelerating the creation of tomorrow’s Internet.the creation of tomorrow’s Internet.

GoalsGoals Enable new generation of applicationsEnable new generation of applications Re-create leading edge R&E network Re-create leading edge R&E network

capabilitycapability Transfer capability to the global Transfer capability to the global

production Internetproduction Internet 206 University Members, Jan. 2005206 University Members, Jan. 2005

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

Abilene Connections :: Apr-2000Abilene International Peering 2006

Research andDevelopment

Commercialization

Partnerships

Privatization

Internet Development Spiral

Today’s Internet

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 BHost E

Host D

Host C

Node 1 Node 2

Node 3

Node 4

Node 5

Node 6 Node 7

Router A

Router B

Router C

Router D

Router E

1. Connection Establishment2. Information Transfer3. Circuit Disconnect

Virtual Circuit Packet Switching-Example

Router F

Packet 1

Packet 2

Packet 3

Packet 1

Packet 2

Packet 3

Timing of Virtual-Circuit Packet Switching

Packet 1

Packet 2

Packet 3

Host 1 Host 2Node

1Node

2

propagation delay between Host 1 and Node 1VC

establishment

VCtermination

Datatransfer

Asynchronous Transfer Mode: ATM

1990’s/00 standard for high-speed (155Mbps to 1990’s/00 standard for high-speed (155Mbps to 622 Mbps and higher) 622 Mbps and higher) Broadband Integrated Broadband Integrated Service Digital NetworkService Digital Network architecture architecture

Goal:Goal: integrated, end-end transport of carry integrated, end-end transport of carry voice, video, datavoice, video, data meeting timing/QoS requirements of voice, meeting timing/QoS requirements of voice,

video (versus Internet best-effort model)video (versus Internet best-effort model) ““next generation” telephony: technical roots next generation” telephony: technical roots

in telephone worldin telephone world packet-switching (fixed length packets, packet-switching (fixed length packets,

called “cells”) using called “cells”) using virtual circuitsvirtual circuits

ATM reference model

How far along are we?

Standardization bodies - ATM Forum, ITU-T Standardization bodies - ATM Forum, ITU-T We may never see end-to-end ATM (1997)We may never see end-to-end ATM (1997)

ATM - too complex - too expansive <IP>ATM - too complex - too expansive <IP> Backbone: - 1995 vBNS (ATM) Backbone: - 1995 vBNS (ATM)

- 1998 Abilene (SONET) - 2000 IP over - 1998 Abilene (SONET) - 2000 IP over DWDMDWDM

Internet technology + ATM philosophyInternet technology + ATM philosophy but ATM ideas continue to powerfully but ATM ideas continue to powerfully

influence design of next-generation influence design of next-generation InternetInternet

ex: ex: MPLSMPLS, admission ctl., resource , admission ctl., resource reservation, …...reservation, …...

Best of Both Worlds

Multiprotocol label switching (Multiprotocol label switching (MPLSMPLS)) MPLS + IP form a middle ground that MPLS + IP form a middle ground that

combines the best of IP and the best of combines the best of IP and the best of virtual virtual circuit switching technologiescircuit switching technologies

ATM and Frame Relay cannot easily come to ATM and Frame Relay cannot easily come to the middle so IP has!the middle so IP has!

Label Encapsulation

MPLS Encapsulation is specified over MPLS Encapsulation is specified over various media types. Top labels may use various media types. Top labels may use existing format, lower label(s) use a new existing format, lower label(s) use a new “shim” label format.“shim” label format.

Label Substitution Have a friend go to B ahead of you using one of the Have a friend go to B ahead of you using one of the

previous two techniques. At every road they reserve previous two techniques. At every road they reserve a lane just for you. At every intersection they post a a lane just for you. At every intersection they post a big sign that says for a given lane which way to turn big sign that says for a given lane which way to turn and what new lane to take.and what new lane to take.

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?What is GENI?GENI is GENI is a facility concepta facility concept being explored by being explored by the US computing community the US computing community

back to an NSF workshop in 2005back to an NSF workshop in 2005focus on focus on architecturalarchitectural research, and research, and provide the provide the experimentalexperimental infrastructure infrastructure needed to support that researchneeded to support that research

focus on the research agenda (and focus on the research agenda (and infrastructure needs) of the infrastructure needs) of the opticaloptical, , wirelesswireless, , sensorsensor network, and network, and distributeddistributed systems communitiessystems communities

GENI (Global Environment for Network Innovations) (2)

The goal of GENI The goal of GENI Goal: a Future Internet that meets the Goal: a Future Internet that meets the demands of 21st centurydemands of 21st century

to increase the to increase the qualityquality and and quantityquantity of of experimental experimental researchresearch outcomes in networking and distributed outcomes in networking and distributed systemssystems

to accelerate the to accelerate the transitiontransition of these outcomes into of these outcomes into products and servicesproducts and services

enhance economic competitiveness and secure enhance economic competitiveness and secure the Nation's futurethe Nation's future

Ultimately, to lead to a Ultimately, to lead to a transition of the transition of the InternetInternet

FIND (Future Internet Network Design) – NSF 2006

FIND asks two broad questions:FIND asks two broad questions: What are the What are the requirementsrequirements for the global network for the global network

in 15 yearsin 15 years How How would we would we re-conceivere-conceive tomorrow's global tomorrow's global

network today, if we could design it from scratch? network today, if we could design it from scratch? FIND program solicits "FIND program solicits "clean slate processclean slate process" " research proposals in the broad area of research proposals in the broad area of network architecture, principles, and designnetwork architecture, principles, and design

FIRE (Future Internet Research and Experimentation) – European 2007

FIRE is an FIRE is an experimentallyexperimentally-driven -driven longlong-term research initiative on -term research initiative on Future Internet Future Internet conceptsconcepts, , protocolsprotocols and and architecturesarchitectures

encompassing technological, industrial and socio-economic encompassing technological, industrial and socio-economic aspects aspects

acting as proof-of-concept of the newly proposed acting as proof-of-concept of the newly proposed technologies and services technologies and services

FIRE RESEARCHFIRE RESEARCH Long term multidisciplinary research on future internet Long term multidisciplinary research on future internet

paradigms paradigms Open to Open to fresh bottom-upfresh bottom-up ideas with ideas with no backwards-no backwards-

compatibilitycompatibility constraints constraints Building on the FET SAC initiative “Situated and Autonomic Building on the FET SAC initiative “Situated and Autonomic

Communications” Communications” Considering at the Considering at the same timesame time technological, economic and technological, economic and

social/policy aspects social/policy aspects Build in from the outset and on all levels the right Build in from the outset and on all levels the right balancebalance

between security / accountability and privacybetween security / accountability and privacy