计算机网络原理课件第一章

Internet是一个特定的、实际运行的internet，是国际互 What is Internet? 连网的简称。 Internet is one special internet;
Internet is a world-wide computer network;
What support the internet and Internet to run well: Various communication protocols
Internet’s connection-oriented service
handshaking: setup (prepare for)
data transfer ahead of time
Hello, hello back human protocol
set up “stat来自百度文库” in two
client/server model
client host requests, receives service from server e.g., WWW client (browser)/ server; email client/server
peer-peer model
minimal (or no) use of dedicated servers e.g.: BT,eMule, Skype
注[1] ISP：Internet service Provider ：
7/44
company network
Chapter 1: Computer Network and Internet
What’s the Internet: “nuts and bolts” view
protocols: control sending,
9/44
Chapter 1: Computer Network and Internet
(3) Network edge: connection-oriented service
Goal:
data transfer between end systems.
TCP service [RFC 793] TCP - Transmission Control Protocol
Bus(总线 Bus(总线) 总线)
Terminator (50 电阻) 电阻)
Host
Host
Host
Terminator (50 电阻) 电阻)
Chapter 1: Computer Network and Internet
1.Computer Network definition and structure
（1）Computer Network ） What is network?—— Human network as an example. What is computer network?
1、Computer Network definition and structure 、
（3）The network edge: ） end systems (hosts):
run application programs e.g., WWW, email at “edge of network”
the internet is the interconnection of “Computer Network” internet是指多个网络相互连接构成的网络，并更多地代 Can be seen as the collection of computer networks, i.e. 表网络互连技术； Network of networks.
receiving of messages
e.g., TCP, IP, HTTP, FTP, PPP
router
Hosts workstation server mobile local ISP
Switch
Internet: “network of networks”
loosely hierarchical public Internet versus private Intranet
6/44
Chapter 1: Computer Network and Internet
What’s the Internet: “nuts and bolts(具体细节 view 具体细节)” 具体细节
millions of connected computing devices: hosts, end-systems pc’s, workstations, servers PDA’s, phones, toasters (烘炉 烘炉) 烘炉 running network applications local ISP[1] router Hosts workstation server mobile
12/44
Chapter 1: Computer Network and Internet
1.Computer Network definition and structure
（5）Another view of computer Network ）
Computer Network = Communication subnet + Resources subnet or Communication subnet + User subnet or Network core + Network edge
教学安排
教学方法：课堂讲授，课后练习，编程及实习 教学手段：教学课件+多媒体投影 学时安排：讲授54学时，期中考试2学时，实验32学时 （7 个必做实验、1个选做实验）。 理论课：期中、期末考核均为闭卷考试 实验课：单列学分，由实验教师按大纲评定成绩。
教材和参考书：
教 材：《Computer Networking—A top-down approach featuring the Internet》 James F.Kurose/Keith W.Ross 《计算机网络—— 自顶向下的方法与Internet特色》 参考书： 1、《数据通信与网络技术》，清华大学出版社，《Data communication and networking》,Behrouz A.Forouzan 2、《现代通信网络技术》,西南交通大学出版社,曾华燊著. 3、《Computer Networks》, Fourth Edition By Andrew S. Tanenbaum
（4）The Network Core ） mesh of interconnected routers
the fundamental question: how is data transferred
through net? circuit switching: a dedicated circuit per call as telephone net packet-switching: data sent thru net in discrete “chunks”
regional ISP
Internet standards
RFC: Request for comments IETF: Internet Engineering Task Force (Internet工程任务组 工程任务组) 工程任务组
company network
8/44
Chapter 1: Computer Network and Internet
11/44
App’s using UDP:
streaming media, teleconferencing, Internet telephony
Chapter 1: Computer Network and Internet
1、Computer Network definition and structure 、
In a computer network, Computer is the element of the set.
5/44
Chapter 1: Computer Network and Internet
1、Computer Network definition and structure 、
（2）internet and Internet ） What is internet?
Computer Network——the collection of computers: Connected Via communication links With the target to share resources Resources include: computer hardware, software, information (data) and something useful to others
Host Host Host Host
Communication Subnet/network core
Host
Host
Resources Subnet/network edge Host
13/44
Chapter 1: Computer Network and Internet
2. Topological structure of Computer Networks
communicating hosts
reliable, in-order byte-stream
data transfer
loss: acknowledgements and retransmissions
TCP Connection: like reg. letter
In a very loose mode; Only the end systems is aware(明白的 明白的); 明白的 Virtual Connection: vs. physical connection in circuit switching.
UDP - User Datagram Protocol [RFC 768]: Internet’s connectionless service no handshaking no flow control no congestion control unreliable data transfer
(3) Network edge: connectionless service
Goal: data transfer between
end systems
same as before!
App’s using TCP:
HTTP (WWW), FTP (file transfer), Telnet (remote login), SMTP (email)
计算机网络原理 Computer Network
课程要求
了解计算机网络的体系结构，掌握OSI/RM、TCP/IP体系结构 掌握计算机网络协议的概念、协议层次及各层次的主要协议 掌握主要的网络传输介质、数据交换的主要类型及基本原理 掌握应用层协议原理及典型的应用层协议编程 掌握传送层主要原理，熟练掌握TCP、UDP原理及编程 掌握网络层主要原理，熟练掌握协议地址、路由原理 掌握链路层及局域网主要概念、标准、差错控制等原理 了解多媒体网络原理 了解网络安全的相关问题、主要原理 了解网络管理的基本问题
flow control:
sender won’t overwhelm receiver
congestion control:
senders “slow down sending rate” when network congested
10/44
Chapter 1: Computer Network and Internet
Switch
routers: forward packets (chunks)
of data thru network Other net devices, e.g. switches regional ISP
communication links
fiber, copper, radio, satellite