PART Ⅱ Introduction to the
Foundation of Information
Technologies
Session 10-11
Telecommunication and Networks
HUANG Lihua, Fudan University
Agenda
1.
2.
3.
4.
Telecommunications
Computer Networks and Enterprise Network
Internet/Intranet/Extranet
Wireless Computing
HUANG Lihua, Fudan University
Feb., - July., 2005
工作站/PC
服务器
双绞线
十楼
¼¯ Ïß Æ÷
光缆
交换机
金融工程实验室
九楼
光缆
八楼
光缆
说明
其它楼层都仿照十楼的
配置，由一台交换机联
数台集线器，以提供足
够的信息点，对高带宽
的系统，例如：服务器
可以直接连接到交换机
双绞线
七楼
光缆
六楼
光缆
集线器
五楼及机房
光纤
У԰Íø
ATM
主交换机
WWW服务器
双绞线
交换机
服务器
四楼
说明
其它楼层都仿照十楼的
配置，由一台交换机联
数台集线器，以提供足
够的信息点，对高带宽
的系统，例如：服务器
可以直接连接到交换机
光缆
三楼
光缆
二楼
光缆
一楼
¹â ÀÂ
数据库、NOTES服务
器
双绞线
交换机
105、106香港班教室
HUANG Lihua, Fudan University
管理学院
李达三楼
网络结构
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
列
网络管理工作站
远程访问服务器
HUB
厂办工作站
（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
纫车间、定型车间、包装车间 )
南楼工作组
Hub
（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
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.
Computer
Communication
Processor
Communication
Processor
HUANG Lihua, Fudan University
Computer
Network
Software
The Spectrum of
Telecommunications-based Service
Available
•
•
•
•
•
•
•
•
•
POTS-plain old
•
Communications
Entertainment •
telephone service
Cellular/PCS systems
•
Mobile radio
•
Video telephony
•
Videoconferencing
•
Telecommuting
•
Internet access
•
Image networking
•
Transaction service
Information
transactions
HUANG Lihua, Fudan University
Broadcast TV
High-definition TV
Enhanced Pay-per-view
Video-on-demand
Interactive TV
Interactive video games
Video catalog shopping
Distance learning
Desktop multimedia
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
00101110100111010010101011101111001000100001011110101101001110100100101100
Analog data transmissionHUANG Lihua, Fudan University
Digital data transmission
(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
PC or
Terminal
Front End
Processor
Computer
Multiplex
Telecommunication media
(channels)
Modem
Modem
HUANG Lihua, Fudan University
Multiplex
Receiver
Front End
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
Terminals
2
2
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
Rj
Ri
Rn
H3
Host
Router or Switch
Node
HUANG Lihua, Fudan University
Hm
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
金属防护层
导体
内导层
HUANG Lihua, Fudan University
外壳
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
DETECTOR
HUANG Lihua, Fudan University
SIGNAL
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
HUANG Lihua, Fudan terabits。*
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
HUANG Lihua, Fudan University
直线波、微波中继站
话，smart phone智能终端、PDA)
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
同步卫星，，22000英里 HUANG Lihua, Fudan University
DOWNLINK
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
TWISTED PAIR
SPEED
300 BPS - 10 MBPS
MICROWAVE
256 KBPS - 100 MBPS
SATELLITE
256 KBPS - 100 MBPS
COAXIAL CABLE
56 KBPS - 200 MBPS
FIBER OPTICS
56 KBPS - 10 GBPS
BPS: BITS PER SECOND
KBPS: KILOBITS PER SECOND
MBPS: MEGABITS PER SECOND
GBPS: GIGABITS PER
SECOND
HUANG Lihua, Fudan University
COST
LOW
HIGH
Advantages and disadvantages of media
Medium
advantages
Inexpensive; Widely available;
Twisted Easy
to
work
with;
Pair
Unobtrusive.
Disadvantages
Emits electromagnetic interference;
Slow(low bandwidth); Subject to
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.
2.
3.
4.
Telecommunications
Computer Networks and Enterprise Network
Internet/Intranet/Extranet
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
OSI
参
考
模
型
应用层
表示层
会话层
传输层
网络层
数据链路层
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
计算机A
传输控制协
议层（TCP）
相同的消息
网间协议
层（IP）
相同数据包
网络接口层
相同数据片
物理网络
相同的帧
应用层
传输控制协
议层（TCP）
网间协议
层（IP）
计算机B
HUANG Lihua, Fudan University
网络接口层
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。
A Document issued
(1)
(2)
(3)
(4)
A Document Package
HUANG Lihua, Fudan University
A Document is traveling on Internet
(1)
(2)
(3)
(4)
Midway Site
User’s Computer
(1)
(1)
(2)
(3)
(4)
(2)
Midway Site
(3)
(4)
Destination Site
(1)
(2)
(3)
(4)
Receiver
HUANG Lihua, Fudan University
TCP/IP（Transmission Control
Protocol /Internet Protocol）
OSI
参
考
模
型
应用层
表示层
会话层
传输层
网络层
应用层
Telnet
FTP
HTTP
SMTP
TCP/IP
传输层
网络层
TCP
UDP
IP
数据链路层 网络接口层 局域网：以太 广域网：
网、令牌环
ATM、帧中
物理层 物理层 网、FDDI等 继 、X.25等
HUANG Lihua, Fudan University
PPP、SLIP
RS-232
模
型
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）
STAR星状结构
USER
USER
HOST
USER
USER
•All computers and other devices are connected
to a central host computer
HUANG Lihua, Fudan University
Computer Network : Topology
（拓扑结构）
BUS总线结构
USER
USER
USER
USER
USER
USER
Lihua, Fudan University by a single circuit
•Links a numberHUANG
of computers
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
WAN
Internet
50Kbps100Mbps
100km---1000km 中小国家、 9.6Kbps45Mbps
州、大国
9.6Kbps大于1000km
地球
45Mbps
HUANG Lihua, Fudan University
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
Embedded
LAN Manufacturing
Marketing
Corporate
Backbone
Accounting
Mainframe
Administrative
Service and
HRM
HUANG Lihua, Fudan University
File server
for backbone
WAN
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.
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CLIENT
•
•
•
•
•
•
USER POINT - OF - ENTRY
COMPUTER / WORKSTATION / LAPTOP
USER INTERACTS WITH CLIENT
THRU GRAPHICAL USER INTERFACE (GUI)
ENTER & RETRIEVE DATA
ANALYZE & REPORT
*
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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
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Type of Client/Server Computing
1.Distributed
Presentation
2.Remote
Presentation
3.Distributed
Logic
4. Remote
Data Mgmt.
5.Distributed
Database
Data Mgmt.
Data Mgmt.
Data Mgmt.
Data Mgmt.
Data Mgmt.
Application
Application
Application
Presentation
Data Mgmt.
Presentation
Presentation
client
Application
Application
Application
Presentation
Presentation
Presentation
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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）。
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B/S与C/S对比
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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
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Agenda
1.
2.
3.
4.
Telecommunications
Computer Networks and Enterprise Network
Internet/Intranet/Extranet
Wireless Computing
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Internet
Structure of the Internet
Host
Host
Host
Network 1 R
R R
Host
Network 2
R
R
R
Network 3
R
R Network 4
R - Router
Host
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Host
A bird’s eye view of the Internet
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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.
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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
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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)
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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
EDU
GOV
MIL
ORG
NET
Typically commercial organizations
Universities, educational institutions
Government, non-military
Militar, Arm, Navy
Miscellaneous organizations
Usually service providers
Examples:
ibm.com
whitehouse.gov
fudan.edu.cn
ibm.net
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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。
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Web Architecture
Database
CGI
公共
网关
接口
TCP/IPBased
Network
Web Clients
Web Servers
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Content
Software
Application
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.
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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
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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
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*
NEXT GENERATION INTERNET
• INTERNET2:
– New protocols, higher transmission speed,
interconnected gigapops (regional high-speed
points-of-presence), connected to highperformance Backbone Network infrastructure.
Will differentiate priorities of messages,
provide video portals for lifelike video
*
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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
*
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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
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Firewall-secured Internet Connection
Internet__
Unknown number
Hackers?
Firewall
Intrane
t
STOP
Firewall bypass
should not be allowed
Corporate Network
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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!
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EXTRANET
• Private Intranet accessible to select
outsiders
• LINK ORGANIZATION TO
– IMPORTANT CLIENTS
– BUSINESS PARTNERS
– TOP EXECUTIVES & BOARD MEMBERS
*
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Company A
Router
The
Internet
Intranet
Intranet
Server
Firewall
Router
Intranet
Intranet
Server
Company B
Firewall
Host
Computer
Intranet and Extranet
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Interorganizational System
The Internet
Company A
Extranet
Intranets
Extranet
Extranet
Customer
Intranets
Intranets
Extranet
Intranets
Extranet
Other Company Locations
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Supplier
E-Business: CISCO applications
INTRANET: Cisco Employee Connection- OA
Oracle ERP Finance System
Peoplesoft ERP HR
Inbound
Logistics
Operations
Outbound
Logistics
Marketing
& Sales
Customer
service
EXTRANET:
Cisco Suppliers
Connection
Customer
-SCM
-”Single Enterprise”
-Direct Fulfillment
-Dynamic Replenishment
-
Web Interface
to CSC
Oracle ERP
Procurement
New Product Introduction
INTERNET: Cisco Connection Online
e Distribution
MarketPlace Product
Customer
promotion
Service
Oracle ERP
SaleForceAuto
Production
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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
*
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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
*
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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
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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?
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