Session 7-12. Modern IT Architecture by yaofenjin

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									  PART Ⅱ Introduction to the
   Foundation of Information
        Technologies


        Session 10-11
Telecommunication and Networks

         HUANG Lihua, Fudan University
                     Agenda

1.   Telecommunications
2.   Computer Networks and Enterprise Network
3.   Internet/Intranet/Extranet
4.   Wireless Computing




                  HUANG Lihua, Fudan University
                      Feb., - July., 2005
                   服务器                                      工作站/PC



                                    双绞线         ¼¯ Ïß Æ÷

               十楼
                     光缆
                            交换机
     金融工程实验室
                   九楼                           说明
                    光缆                     其它楼层都仿照十楼的
                                           配置,由一台交换机联
                   八楼              双绞线     数台集线器,以提供足
                     光缆                    够的信息点,对高带宽
                    七楼                     的系统,例如:服务器
                     光缆                    可以直接连接到交换机
                    六楼
                      光缆
                                     集线器
                         五楼及机房

     光纤        主交换机         交换机              双绞线
У԰Íø
ATM

    WWW服务器                                   服务器
                     四楼
                                                说明
                      光缆                   其它楼层都仿照十楼的
                    三楼                     配置,由一台交换机联
                                           数台集线器,以提供足
                      光缆                   够的信息点,对高带宽
                    二楼                     的系统,例如:服务器
                     光缆
                                                                     管理学院
                                           可以直接连接到交换机




                    一楼
                    ¹â ÀÂ
                                                                     李达三楼
                                                                     网络结构
                                     双绞线

                             交换机
     数据库、NOTES服务
         器
                                         105、106香港班教室
                            HUANG Lihua, Fudan University
               纺织企业网络系统
                                           公用电话网

 主服务器          备份服务器


         磁盘阵           网络管理工作站
          列

                                 远程访问服务器
                                                厂办工作站


                        HUB
                                           (董事长、总经理、财务
                                           外贸 、销售、生产 )



                                    办公大楼工作组

  Hub
        (原料仓库、成品仓库、卡丝车间、缝           Hub
          纫车间、定型车间、包装车间 )                   (辅料仓库、国产及毛
                                            圈机、太和兴车间)


                                              北楼工作组
               安全监视系统
南楼工作组                         安全监视系统
  Which Business Tasks are
Requiring Telecommunications



  Network is Computer.
   Network is System.

       HUANG Lihua, Fudan University
  TELECOMMUNICATIONS
• Communicating information VIA electronic
  means over some distance
• Service provided by telecom companies:
  telephone, mobile phone, wireless
  transmission, data communication, Cable
  TV, satellite, …………..
                       *

              HUANG Lihua, Fudan University
    Telecommunication Concept
 • Telecommunication is the electronic
   collection, exchange, and processing of data
   or information, including text, picture, voice,
   and other information that is digitally coded
   and intelligible to a variety of electronic
   machines.
                                              Communication   Computer
            Communication
Computer      Processor                         Processor
                                                               Network
                                                               Software
                    HUANG Lihua, Fudan University
             The Spectrum of
      Telecommunications-based Service
                Available
•   POTS-plain old                                   •     Broadcast TV
    telephone service   Communications Entertainment
                                                     •     High-definition TV
•   Cellular/PCS systems                             •     Enhanced Pay-per-view
•   Mobile radio                                     •     Video-on-demand
•   Video telephony                                  •     Interactive TV
•   Videoconferencing                                •     Interactive video games
•   Telecommuting                                    •     Video catalog shopping
•   Internet access                                  •     Distance learning
•   Image networking                                 •     Desktop multimedia
•   Transaction service
                            Information
                            transactions

                           HUANG Lihua, Fudan University
                     Electronic Signals
   • Telecommunication media can carry two basic
     type of signals, ANALOG(模拟) and DIGITAL
     (数字).
   • Analog signals are continuous waves that ―carry‖
     information by altering the characteristics
     ( amplitude振幅 and frequency频率) of the wave.
   • Digital signals are discrete on-off pulses that
     convey information in terms of 1s and 0s, just like
     the CPU in computer.



                                               0 1 0 0 1 0 1 0
0010111010011101001010101110111100100010000101111010110100111
     Analog data transmission                       Digital data transmission
                            HUANG Lihua, Fudan University
          (wave signal)                                   (pulse signal)
              Telecommunication System
     • Computers
     • Terminals (Input / Output Devices)
     • Communications Channels (media)
     • Processors (Modems调制解调器; multiplexers(多
       路转接器;Internetwork Processors)
 Host• Network software                     Host
Computer                                                               Computer

                         Telecommunication media
                                (channels)
 PC or                                                                 Front End
             Multiplex   Modem           Modem             Multiplex
Terminal                                                               Processor

 Front End                HUANG Lihua, Fudan University
                                                          Receiver
 Processor
      PROTOCOL(协议)
• rule and procedures to govern transmission
      between component in a network.
                    *




              HUANG Lihua, Fudan University
Components of Telecommunication
     Systems : Computers
• Host computer (Mainframe computer)
• Front-end processor (Midrange computer)
• Network Server (Microcomputer)


                                                  4,5
1         2                                   2


                           3
              HUANG Lihua, Fudan University
Components of Telecommunication
    Systems : Terminals
   •   Personal computers
   •   Network computers
   •   Video terminals
   •   Other I/O devices( Telephone, POS)

   1           2                                   2


Terminals                       3
                   HUANG Lihua, Fudan University
          Communication Processors
• Modem: Modulation and Demodulation
   – Modulation(调制):perform conversion from digital to analog;
   – Demodulation(解调):perform conversion from analog to digital.
• Multiplexor(多路转接器):An electronic device that allows
  a single communication channel to carry transmissions
  simultaneously from many source.
• Internetwork Processors :A specialized computer that
  manages all routing communications with peripheral
  devices.
   –   Switches交换机
   –   Routers路由器
   –   Hubs网络集线器
   –   Gateways网关
                      HUANG Lihua, Fudan University
     Communication Network
H1           R1
                                                          Hi
H2             R2                Ri

                  Rj                Rn
                                                          Hm
H3
                                       Router or Switch
                                            Node
      Host    HUANG Lihua, Fudan University
     Communication Media (channel)

• Means by which data are transmitted.
• Cable Media:
  – (1)Twisted Pair Wire双绞线(电话线);(2)
    Copper Wires, (3)Coaxial Cable同轴电缆(有
    线电视), (4) Fiber Optics
                              *
           双绞线



   PVC外壳
                 HUANG Lihua, Fudan University
Communication Media (channel)
• Wireless Media:
  – (1) Microwave; (2) Satellite; (3) Global
    Positioning Systems; (4) Radio; (5)
    Infrared; (6) Cellular Radio Technology;
    (7) Mobile Computing.
                    *
                  绝缘层                  绝缘层
  外壳


                                                       外导线




                                         内导层      外壳
         金属防护层          导体
                  HUANG Lihua, Fudan University
            FIBER OPTICS光纤
 • Made of thousands of super clear glass strands
 • Fast, light, durable
 • trillions of bits per second, full duplex, 以光脉冲
   形式在电缆中传输
 • EXPENSIVE, HARDER TO INSTALL

  • OFTEN USED AS BACKBONE OF
    NETWORKS
                     *     PHOTO
SIGNAL  LASER     CABLE                                     SIGNAL
                                                 DETECTOR
                 HUANG Lihua, Fudan University
                   FIBER OPTICS
• BACKBONE主干网
  – Fiber optics cable carries light signals to distribution
    nodes, which use copper wires to user
• DENSE WAVE DIVISION MULTIPLEXING
  (DWDM)高密度分波多路转接器
  – Next-generation, uses many colors, (up to 160) each a
    channel, increases capacity of a fiber to 6.4 terabits per
    second
  – DWDM使用不同颜色的光缆或不同波长在同以时间
    及同一光缆上传送不同的数据流来提高传送容量。
  – DWDM每条光缆包含了最多160个波长,每秒最多
    可以在单一光缆上传送6.4 terabits。*
                   HUANG Lihua, Fudan University
   Wireless Transmission (Megahertz兆赫)

• 105 - 108: AM Radio; Short Wave; FM; VHF-TV
• 108 - 1010: UHF-TV, Cellular Phones(移动电
  话,天线与基地台,8英里)), RAM Mobile,
  Data, Cordless Phone, Paging(呼叫系统),
  Narrow Band PCS, Industrial
• 1010 - 1012: Radar, Microwave
• 1013 - 1014: Infra Red, Remote Control, Wireless
• 1015 - 1016: Visible Light; Fiber Optics
• 1018 - 1022: X-Ray, Gamma, Cosmic, Personal
  Communication Services (PCS)(数字移动电
直线波、微波中继站
  话,smart phone智能终端、PDA)
                 HUANG Lihua, Fudan University
     Frequency Ranges for
Communications Media and Devices




  频谱图     HUANG Lihua, Fudan University
         Low-Orbit Satellite
      低轨道通信卫星,作为中继站
                             MICROWAVE
                            TRANSMISSION



                 UPLINK
                                              DOWNLINK




同步卫星,,22000英里 HUANG Lihua, Fudan University
      Wireless Transmission
           Technology
• PAGING SYSTEM: 呼叫系统
  – Small Page Beeps when Receives Short Message
• CELLULAR TELEPHONE: 蜂窝电话
  – Device uses Radio Waves to Reach Antennas Within
    Areas Called Cells
• MOBILE DATA NETWORKS:
  – Radio - based Data Network using Hand-held
    Computers. Cheap, Efficient 数字移动电话,smart
    phone智能终端、PDA
• *
              HUANG Lihua, Fudan University
Communication Media (channel)

• TRANSMISSION SPEED(传输速度):
  Bits per Second (BPS) or Baud(波特)
• BANDWIDTH(带宽): Capacity of
  Channel; Difference between Highest &
  Lowest Frequencies



              HUANG Lihua, Fudan University
            Speed and Cost of Media
  MEDIUM                SPEED               COST
TWISTED PAIR          300 BPS - 10 MBPS     LOW

MICROWAVE             256 KBPS - 100 MBPS

SATELLITE             256 KBPS - 100 MBPS

COAXIAL CABLE         56 KBPS - 200 MBPS

FIBER OPTICS           56 KBPS - 10 GBPS    HIGH
BPS: BITS PER SECOND
KBPS: KILOBITS PER SECOND
MBPS: MEGABITS PER SECOND
GBPS: GIGABITS PER SECONDUniversity
                 HUANG Lihua, Fudan
Advantages and disadvantages of media
Medium     advantages                         Disadvantages
        Inexpensive; Widely available;        Emits electromagnetic interference;
Twisted Easy     to    work      with;        Slow(low bandwidth); Subject to
Pair    Unobtrusive.                          interference; Easily tapped(low
                                              security).
Coaxial Higher bandwidth than twisted Relatively              expensive       and
Cable     pair; Less susceptible to inflexible; Somewhat difficult o
          electromagnetic interference. work with; Easily tapped(low to
                                              medium security)
Fible     Very high bandwidth; Smaller Difficult to work with (difficult to
optic     and lighter than coaxial cable; splice); Expensive; Relatively
cable     Difficult to tap                    inflexible.
Micro- Very          high     bandwidth; Must             have       unobstructed
wave      Relatively inexpensive.             line-of-sight;     Subject       to
                                              interference from rain; Must use
                                              encryption for security;
Satellite Very high bandwidth; Large Expensive; Must have unobstructed
          coverage on earth.                  line-of-sight; Signals experience
                                              propagation delay; Must use
                                              encryption for Security
                         HUANG Lihua, Fudan University
Individual Assign for Session 9-10
• Individual assignment for session 10
   – Reading Materials: Textbook: chapter 6
   – P. 206: Review Quiz: write down in your book.
• Group Assignment: wireless LAN design
   – How do you suggest Fudan should build wireless LAN
     that permit students to log on Internet anywhere in
     Campus. What kinds of wireless technologies may be
     used in Fudan WLAN.
   – Write and submit into Vcampus.

                   HUANG Lihua, Fudan University
  PART Ⅱ Introduction to the
   Foundation of Information
        Technologies

        Session 10-11
Telecommunication and Networks
             (2)

         HUANG Lihua, Fudan University
                     Agenda

1.   Telecommunications
2.   Computer Networks and Enterprise Network
3.   Internet/Intranet/Extranet
4.   Wireless Computing




                  HUANG Lihua, Fudan University
         Computer Network
• A computer network is a group of
  interrelated components including computer
  system, telecommunication system and
  network software.
  –计算机网络是由计算机系统,数
   据通信系统和网络系统软件组成
   的一个有机整体。
               HUANG Lihua, Fudan University
 Computer Network Architecture
• Protocols, Standards, Interfaces, and
  Topologies
  – 使不同的计算机、不同的通讯系统和不同的
    应用能够互相连接(互连)和互相操作(互
    操作)提供相应的规范和标准




                HUANG Lihua, Fudan University
   Protocols网络协议
• Rules & procedures to govern transmission
  between components in a network. It‘s
  principal functions are line access to
  collision avoidance.
• OSI
• Transmission Control Protocol /Internet
  Protocol (TCP/IP)

               HUANG Lihua, Fudan University
         ISO/OSI (开放系统互连 )
             分层参考模型

资源子网
       应用层
 OSI   表示层
  参    会话层
 考     传输层
 模     网络层
       数据链路层
 型
       物理层
通信子网
               HUANG Lihua, Fudan University
               TCP/IP
       (Transmission Control
     Protocol/Internet Protocol)
• Open suite of protocols for connectivity
  developed in 1970s
• Provides standards for breaking messages
  into packets, routing them to destination
  addresses, and reassembling them at end
• Allows for communication regardless of
  hardware/software
               HUANG Lihua, Fudan University
   TCP/IP: Four-Layer Reference
              Model
• Application layer: Communication between
  applications and other layers
• Transport layer: Acknowledging and
  sequencing packets to/from application
• Internet layer: Addressing, routing,
  packaging data packets
• Network interface layer: Placing packets on
  and receiving them from network medium
               HUANG Lihua, Fudan University
            TCP/IP
• TCP:实现传送,把终端用户的应用数
  据分解为TCP的包(packet)
 – 包=标明发信主机地址的包头+重新组合数据
   的信息+确保数据包不被中断的信息。
• IP:从TCP层接受数据片,并进一步将数
  据包分解,
 – IP包=包含具有地址信息的包头+TCP包。确
   定每个包从发送者到接受者的路由。
        HUANG Lihua, Fudan University
    How Does Internet work?
• TCP/IP(传输控制协议/网间协议):

应用层    传输控制协             网间协议
                                           网络接口层
       议层(TCP)           层(IP)
计算机A


   相同的消息     相同数据包              相同数据片             物理网络
                                           相同的帧


       传输控制协               网间协议            网络接口层
应用层
       议层(TCP)             层(IP)
计算机B

           HUANG Lihua, Fudan University
     How Does Internet work?
• TCP/IP成功的关键在于它以很小的包发送信息,而这些
  小的信息包并不需要顺序到达对方——甚至不需要按
  同一路径来传送。而这些信息——无论它们被怎样分
  割,无论选取哪条路径——都能完整无缺地组合起来。


                                                 (1)      (2)




                                                 (3)      (4)
 A Document issued                              A Document Package

                     HUANG Lihua, Fudan University
A Document is traveling on Internet
                   (1)    (2)




                   (3)    (4)



                                                         Midway Site
User‘s Computer                         (1)   (2)




                                        (3)   (4)
     (1)   (2)

                                        Midway Site
     (3)   (4)
                           (1)    (2)




                           (3)    (4)




Destination Site                              Receiver

                   HUANG Lihua, Fudan University
        TCP/IP(Transmission Control
         Protocol /Internet Protocol)

      应用层
OSI         应用层       Telnet          FTP        HTTP     SMTP
      表示层
参     会话层
                                                                   TCP/IP

考     传输层
            传输层               TCP                   UDP             模
模     网络层   网络层                             IP                      型
      数据链路层 网络接口层 局域网:以太 广域网:                           PPP、SLIP
型                 网、令牌环  ATM、帧中
       物理层 物理层 网、FDDI等 继 、X.25等                          RS-232


                HUANG Lihua, Fudan University
 Computer Network:Standards
• IEEE 802.1── 通用网络概念及网桥等
  IEEE 802.2── 逻辑链路控制等
  IEEE 802.3──CSMA/CD访问方法及物理层规定
  IEEE 802.4──ARCnet总线结构及访问方法,物理层规定
  IEEE 802.5──Token Ring访问方法及物理层规定等
  IEEE 802.6── 城域网的访问方法及物理层规定
  IEEE 802.7── 宽带局域网
  IEEE 802.8── 光纤局域网(FDDI)
  IEEE 802.9── ISDN局域网
  IEEE 802.10── 网络的安全
  IEEE 802.11── 无线局域网

           HUANG Lihua, Fudan University
 Current Transmission Standards
• FDDI:Fiber Distributed Data Interface(光纤分布式数据
  接口);
• ATM:Asynchronous Transfer Model (非同步传输);
      • 将传输对象切割成固定长度53组8字节的包,消除通讯协议之间
        的转换,允许在任何速度的网络中传输
• ISDN:Integrated Services Digital Network (集成服务数
  字网络).
      • 分两层传输,均使用一组B(bearer)通道传送声音和数据,利用D
        (delta)通道来传送信号与控制类信息
         – Basic Rate ISDN(128 kbps) and Primary Rate ISDN ( 1M kbps)
• ADSL: Asymmetrical Digital Subscriber Line, 非对称数
  字用户线路),
      • 比ISDN传输快,接受时可达 1.5-9 Mbps, 传送时可达640K BPS


                      HUANG Lihua, Fudan University
Computer Network:Interface
• (1) Parallel Data Transfer:
   – Both data and control signals are transmitted,即一个字节的所有
     数据位同时传输。
   – often used for local communication.
   – 对一个计算机而言,通常用于发送数据给打印机。
• (2)Serial Data Transfer:
   – bit by bit,即一个信息单元跟着另一个信息单元。对于计算机
     来说,串行传输意味着字节被分成独立的位,在通信介质上
     一个接一个地传输。
   – often used for long-distance communication.
   – 对一个计算机而言,通常用于调制解调器和网络通信。


                     HUANG Lihua, Fudan University
    Computer Network : Topology
          (拓扑结构)
                     USER
STAR星状结构

         USER        HOST        USER



                     USER

•All computers and other devices are connected
to a central host computer University
                   HUANG Lihua, Fudan
      Computer Network : Topology
            (拓扑结构)
BUS总线结构
         USER       USER       USER




         USER       USER       USER



•Links a number of computers by a single circuit
              HUANG Lihua, Fudan University
     Computer Network : Topology
           (拓扑结构)
RING环状结构                  USER



           USER                                 USER



                          USER

 •All computers are linked by a closed loop.
                HUANG Lihua, Fudan University
   Computer Network Types:
   LAN, MAN,WAN
(1) LOCAL AREA NETWORK (LAN局域网):
    Dedicated Channels; Limited Distance (from
    hundreds meters to 10 kilometers radius); Can
    Share Expensive Hardware & Software
(2) Metropolitan Area Network(MAN城域网或地
    区网):Limited Distances (from 10 kilometers
    to 100 kilometers); Transmission speed higher
    than LAN.
*

                HUANG Lihua, Fudan University
       LAN




HUANG Lihua, Fudan University
     Computer Network Types
• (3) Wide Area Network (WAN):
• Network spans larger geographic distances;
• Can include cable, satellite, microwave;
• Switch Lines: Route Determined by Current
  Traffic;
• Dedicated Lines: Constantly Available for
  High-Volume Traffic
               HUANG Lihua, Fudan University
           Network Comparison
网 络        覆盖直径(数量级) 计算机所处 传输速率
                     范围

LAN        10m---10km           房间、建筑、4Mbps-2Gbps
                                校园

MAN        10km---100km         城市                50Kbps-
                                                  100Mbps
WAN        100km---1000km 中小国家、 9.6Kbps-
                                州、大国              45Mbps
Internet   大于1000km             地球                9.6Kbps-
                    HUANG Lihua, Fudan University 45Mbps
         Network Application
• (1) Campus Network(校园网), Enterprise
  network(企业网), Public network(公用网),
  Private network(专用网),Intranet(内联
  网),Extranet(外联网);
• (2) PRIVATE BRANCH EXCHANGE (PBX): is
  strongly related to the LAN. Firm‗s telephone
  Switching System can carry both voice and data.



                HUANG Lihua, Fudan University
  Network Application (con‘t)
• (3) Value-Add Network(VAN,增值网)
  –   Private; Multipath; Data only;
  –   3rd Party Managed
  –   Used by Several organizations
  –   Subscription basis
  –   Form of VAN: Packet Switching
• 4)Virtual Private Network(VPN,虚拟
  专用网)
                 HUANG Lihua, Fudan University
 Computer Network: Connection
• Gateway(网关,又称网间连接器):
  – connects the LAN to public networks or other corporate
    network , or connects dissimilar networks by translating
    from one set of protocols to another.
• Bridge(网桥):
  – connects two networks of the same type.(通常连接数
    量不多的同一类型的网段)
• Router(路由器):
  – routes messages through several connected LANs or to
    a WAN.
     • 在多个网络和介质之间实现网络互联,主要任务是把通信
       引导到目的地网络,然后到达特定的节点站地址。
                   HUANG Lihua, Fudan University
 Computer Network: Connection
• Switch, switch Hub:    交换机,又称交换式集线器。
   – 交换机(Switch):也叫交换式集线器,它通过对信息进行重新生
     成,并经过内部处理后转发至指定端口,具备自动寻址能力和
     交换作用,由于交换机根据所传递信息包的目的地址,将每一
     信息包独立地从源端口送至目的端口,避免了和其他端口发生
     碰撞。它可以通过跳线或软件设定来实现一个端口数据向多个
     端口转发。
• Repeater (中继器)
   – 叫做转发器或重发器,它是用于物理层的一种介质连接设备,
     其作用实质上是在一定限度内扩展传输距离,它只能发送信号,
     不进行任何其他过滤处理。(将已经衰减得不完整的信号经过整
     理,重新产生出完整的信号再继续传送)
• HUB(集线器):多端口的中继器。
                   HUANG Lihua, Fudan University
    ENTERPRISE NETWORK
• Enterprise Networking:
  – An arrangement of the organization‘s hardware,
    software, telecommunication, and data resources to put
    more computing power on the desktop and create a
    company_wide network linking many small network.
• Open Systems.
• Most organizations have multiple LANs and may
  have multiple WANs, which are interconnected to
  form an enterprise_wide network.

                  HUANG Lihua, Fudan University
    ENTERPRISE NETWORK---for example
                      Embedded
                        LAN
                                                                Backbone WAN
                 Finance                     Marketing



Embedded                   Corporate
  LAN Manufacturing                                         Mainframe
                           Backbone
                                                                         File server
                                                                        for backbone
                                           Administrative                   WAN
                       Accounting           Service and
                                                HRM



                       HUANG Lihua, Fudan University
Evolution of Network Computing
• Host/Terminal (主机/终端型)
  – 这一阶段是以大、中、小型机为中心的集中应用模
    型,所有的信息处理均依赖于主机。
• Client/Server (客户机/服务器型)
  – 这一阶段的C/S模型是基于网络的分布式应用模型
• Browser/Server(基于Internet的分布式对象模型)
  – 这是目前深受欢迎的一种先进结构 ,实质上是一种
    基于Web的 分布式对象技术的应用模型。


             HUANG Lihua, Fudan University
 Network Computing Model ----
   Client/Server Architecture
• This architecture divides processing into ―client‖
  and ―server‖,
• The components of an application are distributed
  over the enterprise rather than being centrally
  controlled.
• There are three application components that can be
  distributed: the presentation component, the
  applications(or processing) logic, and the data
  management component.
                 HUANG Lihua, Fudan University
                  CLIENT

•   USER POINT - OF - ENTRY
•   COMPUTER / WORKSTATION / LAPTOP
•   USER INTERACTS WITH CLIENT
•   THRU GRAPHICAL USER INTERFACE (GUI)
•   ENTER & RETRIEVE DATA
•   ANALYZE & REPORT
                       *

                HUANG Lihua, Fudan University
              SERVER
•   COMPUTER SATISFIES USER‘s NEEDS
•   NOT VISIBLE TO USER
•   PROCESSING
•   ACCESS TO DATABASES
•   服务器:是提供资源的程序和计算机
•   客户机:是使用资源的程序和计算机


             HUANG Lihua, Fudan University
                Type of Client/Server Computing
1.Distributed      2.Remote         3.Distributed           4. Remote     5.Distributed
Presentation      Presentation         Logic                Data Mgmt.      Database

Data Mgmt.       Data Mgmt.        Data Mgmt.               Data Mgmt.    Data Mgmt.

Application       Application       Application

Presentation



                                                                         Data Mgmt.

                                   Application          Application      Application

Presentation     Presentation      Presentation         Presentation     Presentation

           client           HUANG Lihua, Fudan University
     B/S(浏览器/服务器)
 B/W/D(浏览器/WEB服务器/数据服务器)
• 所谓B/S(Brower/Server,浏览器/服务器)结构是指可以直接通
  过Internet网访问服务器的结构,B/S结构无需关心服务器放在哪
  些,只要可以上网,就可以象访问一般网站那样访问企业的应用,
  进行业务的处理。
• 传统的C/S体系结构虽然采用的是开放模式,但在特定的应用中
  无论是Client端还是Server端都还需要特定的软件,没能提供用户
  真正期望的开放环境;
• B/S结构则不同,它的前端是以TCP/IP协议为基础的,企业内
  的WWW服务器可以接受安装有Web浏览程序的Internet终端的访
  问,作为最终用户,只要通过Web浏览器,各种处理任务都可以
  调用系统资源来完成,这样大大简化了客户端,减轻了系统维护
  与升级的成本和工作量,降低了用户的总体拥有成本(TCO)。

             HUANG Lihua, Fudan University
B/S与C/S对比




 HUANG Lihua, Fudan University
        Peer-to-Peer Network
• P2P is a civilization-altering event for
  media industry. Every consumer now is a
  producer, distributor, and marketer of
  information content or intellectual property.
  – Napster architecture: a central server to other
    peers
  – Gnutella architecture: no-central directory or
    server
                 HUANG Lihua, Fudan University
                     Agenda

1.   Telecommunications
2.   Computer Networks and Enterprise Network
3.   Internet/Intranet/Extranet
4.   Wireless Computing




                  HUANG Lihua, Fudan University
             Internet
Structure of the Internet
                 Host
                                                   Host




  Host
              Network 1 R           R       Network 2
                  R R
  Host            R                     R
              Network 3      R      R Network 4


R - Router
                      Host                              Host

                HUANG Lihua, Fudan University
A bird‘s eye view of the Internet




          HUANG Lihua, Fudan University
                      Internet
• Internet is a network that connects hundreds of
  thousands of internal organizational computer
  networks worldwide.
• An Internet Server Provider(ISP) is a commercial
  organization with a permanent connection to the
  Internet which sells temporary connections to
  subscribers.
• Who control Internet? Nobody. Internet is neither an
  organization nor a thing. Internet is just existence.
  Internet is operating by user‘s cooperation each other.


                   HUANG Lihua, Fudan University
 What does it mean to be on the
           Internet?
• Run TCP/IP protocol
• Have an IP address
• Have ability to send IP packets to other
  machines on the Internet




               HUANG Lihua, Fudan University
       Understanding Internet
            Addresses
• 18.154.0.27
    – uniquely assigned to a specific Internet connection
      point (NOT machine!) by NIC
    – 32-bit address
    – each number between dots is the decimal rep of 8 bits
      in the address
    – In this case:
       • 18 specifies MIT (MIT owns all addresses 18.xxx.yyy.zzz)
       • 154 specifies the subnet corresponding to building E56
       • 0.27 is host number within the subnet
    – Every internet address can optionally have a
      descriptive host name (e.g.LASAGNA.MIT.EDU)
                    HUANG Lihua, Fudan University
                  IP地址
• IP地址码分配是分级进行的:负责全球
  的是IANA(Internet Assigned Numbers
  Authority),将部分IP地址分配给地区级的
  IR(Internet Registry). 3 IR---InterNIC负责
  北美、RIPENIC负责欧洲地区、APNIC
  负责亚太区。
• 中国互联网信息中心以国家NIC身份与
  1997年1月成为APNIC的成员。
              HUANG Lihua, Fudan University
         域名:字符地址名
• 世界上任何个人和单位都可以通过NSI
  (Network Solution Inc.)申请国际顶级域
  名下的二级域名。国际顶级域名有:
  COM   Typically commercial organizations
  EDU   Universities, educational institutions
  GOV   Government, non-military
  MIL   Militar, Arm, Navy
  ORG   Miscellaneous organizations
  NET   Usually service providers                 Examples:
                                                   ibm.com
                                                  whitehouse.gov
                                                      fudan.edu.cn
                    HUANG Lihua, Fudan University
                                                       ibm.net
              What is the WWW
•   An application framework for accessing linked documents
    spread out over the Internet
•   Invented by Tim Berners-Lee at CERN in 1989
•   The WWW definition consists of:
     – HTTP: a protocol for allowing Web clients to converse with Web
       servers
     – HTML: a language for preparing Web pages
•   3W:主要有页组成,页有成千上万个,遍布于 INTERNET上。
    每一页与其他页相连,其他页又与连外的其他页相连,如此复杂
    地连接起来。
•   Web是建立在客户/服务器模型之上,以HTML语言和
    HTTP协议为基础,能够提供面向各种Internet服务的、
    一致的用户界面的信息浏览系统。

                      HUANG Lihua, Fudan University
              Web Architecture
                                                         Database


               TCP/IP-                             CGI
                                                   公共    Content
                Based
               Network                             网关
                                                   接口
                                                         Software
                                                         Application
Web Clients                       Web Servers




                   HUANG Lihua, Fudan University
  The Web is NOT The Internet
• The Internet
    – A global computer network using the TCP/IP protocol
      to implement the transport and network layers
• The WWW
    – An application layer framework running on top of a
      TCP/IP network
    – Just one of many possible ways to talk to other
      computers on the Internet
    – Other ways:
       • email, ftp, telnet, etc.




                      HUANG Lihua, Fudan University
              WWW vs. Internet
• ―Being on the Internet‖
    – Have an IP address
    – Use TCP/IP protocol
    – Can send and receive packets to/from all other
      machines on the Internet
• ―Being on the Web‖
    – Being on the Internet
    – Using Web software to connect with other machines
      on the Web
       • Web client software
       • Web server software
• A machine can use the Internet but not the Web
    – Example: telnet
                   HUANG Lihua, Fudan University
       Next Generation Internet
• BROADBAND: Fiber optics and related
  technology will provide much higher delivery
  speed (target: 10 to 100 million bits per second to
  the desktop)
• INTERNET2
   – Internet2是一个项目,有美国180个单位参与。项目
     目的在于提供下一代网上应用,包括
      • 远程诊断 Remote diagnosis、数字图书馆Digital libraries 、
        远程教育Distance education、在线模拟、仿真Online
        simulation 、虚拟实验室 Virtual laboratories等
   – Research networks with new protocols and
     transmission speeds
   – Provide infrastructures for supporting high bandwidth
     Internet applications
                    HUANG Lihua, Fudan University
                                 *
  NEXT GENERATION INTERNET
• INTERNET2:
  – New protocols, higher transmission speed,
    interconnected gigapops (regional high-speed
    points-of-presence), connected to high-
    performance Backbone Network infrastructure.
    Will differentiate priorities of messages,
    provide video portals for lifelike video
                            *


               HUANG Lihua, Fudan University
      THE WIRELESS WEB
• Mobile Commerce/business
     (m-commerce m-business)
• Access to Web on the go : Anywhere, any
  time, many functions
  – INFORMATION-BASED SERVICES
  – TRANSACTION-BASED SERVICES
  – PERSONALIZED SERVICES
                           *
              HUANG Lihua, Fudan University
               INTRANET

• An internal network based on Internet networking
  standards and WWW technology that can provide
  access to data across the enterprise.
• Intranet uses the existing company network
  infrastructure along with Internet connectivity
  standards and software developed for WWW.
• Intranet overcomes computer platform difference.
• FIREWALL: Security System to Prevent Invasion
  of Private Networks

                 HUANG Lihua, Fudan University
     Firewall-secured Internet Connection



Internet__          Firewall
Unknown number
                                                    Intrane
Hackers?
                                                       t




                   STOP
   Firewall bypass
   should not be allowed                                   Corporate Network
                           HUANG Lihua, Fudan University
                        Firewalls
• Protect Intranets from outside attacks
   – While allowing Intranet members access to the outside
     world
• Usually special programs at the Intranet gateway
   – monitor all packets that go in and out of the Intranet
   – Incoming traffic:
      • allow packets from ―Friendly‖ IP addresses to pass
      • return the rest to sender
   – Outgoing traffic:
      • similar controls, possibly to prevent employees from playing
        during company time!
                      HUANG Lihua, Fudan University
              EXTRANET
• Private Intranet accessible to select
  outsiders
• LINK ORGANIZATION TO
  – IMPORTANT CLIENTS
  – BUSINESS PARTNERS
  – TOP EXECUTIVES & BOARD MEMBERS
                             *

                HUANG Lihua, Fudan University
  Company A
                           Router                       The
                                                      Internet

       Intranet

                  Intranet                 Firewall         Firewall
                  Server


                                           Router
Intranet

                  Intranet                Host
                  Server                  Computer


     Company B       Intranet and Extranet
                     HUANG Lihua, Fudan University
           Interorganizational System
                                                            The Internet
                        Company A

                            Intranets
     Extranet                                      Extranet

                             Extranet
Customer    Intranets                           Intranets    Supplier



    Extranet                                    Extranet
                            Intranets



              Other Company Locations

                HUANG Lihua, Fudan University
               E-Business: CISCO applications
           INTRANET: Cisco Employee Connection- OA
                                  Oracle ERP Finance System
                                       Peoplesoft ERP HR
    Inbound                 Operations             Outbound     Marketing    Customer
    Logistics                                                   & Sales      service
                                                   Logistics
 EXTRANET:
Cisco Suppliers
  Connection
-SCM                                                                                        Customer
-‖Single Enterprise‖
-Direct Fulfillment
-Dynamic Replenishment
                                   New Product Introduction
-


Web Interface                     INTERNET: Cisco Connection Online
to CSC                                 e Distribution   MarketPlace Product      Customer
                                                                     promotion    Service
Oracle ERP               Oracle ERP                                 SaleForceAuto
Procurement              Production
                                      HUANG Lihua, Fudan University
                         Management
    BENEFITS & LIMITATIONS OF
     INTRANETS & EXTRANETS
BENEFITS:
• Standard Documents Always Current, Available.
  Less Expensive than Paper
• Can Create, Coordinate New Documents
• Virtual Conferencing
• Project, Order Tracking Simplified
                         *


                HUANG Lihua, Fudan University
    BENEFITS & LIMITATIONS OF
     INTRANETS & EXTRANETS
LIMITATIONS:
• Can‘t Replace Large TPS Programs (e.g.: Payroll;
  Accounting; Production / Operations; Marketing)
• Too Slow for High-Speed Data Transfer
• Not yet as Functional as Groupware
• Require Tight Security Control and Careful
  Management Planning
                          *

                 HUANG Lihua, Fudan University
   INTERNET CHALLENGES
• SECURITY: Exposure to Thieves & Vandals;
  Hackers Steal, Use Passwords; Not Yet Safe for
  Large Business Transactions
• TECHNOLOGY: Lack of Uniform Standards;
  Transfer of Graphics, Video can be Costly
• LEGAL ISSUES: Need More Laws Governing
  Electronic Commerce; Are e-mail Contracts,
  Electronic Signatures Legal?
                         *

                 HUANG Lihua, Fudan University
              Network Trends
•    Internet2
•    Wireless Network
    – WAP (Wireless Application Protocol)
    – Bluetooth wireless device connectivity
    – 802.11无线连接标准
    – I-mode



                  HUANG Lihua, Fudan University
      Assignment for Session 9-10
• Individual assignment for session 10
    – Reading Materials: Textbook: chapter 6
    – P. 206: Review Quiz: write down in your book.
• Group Assignment: wireless LAN design
    – How do you suggest Fudan should build wireless LAN that permit students to
      log on Internet anywhere in Campus. What kinds of wireless technologies
      may be used in Fudan WLAN.
    – Write and submit into Vcampus.
• Individual preparation for session 11
    – Reading material: Textbook chapter 7 and Cisco Systems Architecture
        • What is the legacy system problem at Cisco? How big a problem is it?
        • How important is the ERP to solution of the problem and to the overall
          architecture? Do you see the ERP component as something that will be
          undertaken by some, most or all companies at they build their information age IT
          architecture?
        • What are the essential components of Cisco‘s Strategic I-Net? What is the role of
          Cisco‘s Strategic I-Net?

                            HUANG Lihua, Fudan University

								
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