计算机网络概论 英文版精品PPT课件
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计算机网络基础知识ppt课件 英文版
sketch map
Main function: to achieve the communication and resource sharing1． Basic function: data communication Main features: resource sharing
data
Classification: wide area network （WAN）：Tens to thousands of kilometers local area network （ALN） A few meters to a few kilometers metropolitan area network（MAN） （Between WAN and LAN）
1.2
The basis of computertion -- in the form of an electrical signal to the data transmitted from one end to the other end. 2、 The m ai n technol ogy -- "t he maxi m um transmission rate index of data communication" 3、Modulation, demodulation (Modem): converting the data signals and analog signals.
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What is a computer network
? ?
The computer network is the computer system in different geographical location and function of independent by communication lines are interconnected, the system realizes the sharing and communication of cyber source in the network management software
计算机网络英文教材ppt第二章
Chapter 2 The Physical Layer
30
2.5.3 The Local Loop: Modems, ADSL, and Wireless
Figure 2-23. The use of both analog and digital transmission for a computer to computer call. Conversion is done by the modems and codecs.
3
Chapter 2 The Physical Layer
DTE
DCE
传输介质 DCE
DTE
用户环境
通信系统
Chapter 2 The Physical Layer
用户环境
4
Chapter 2 The Physical Layer
DTE: Equipment that hopes to connect the network. Such as computer, terminal, etc.
2
Chapter 2 The Physical Layer
The definition of physical layer:
the interface between DTE(Data
Terminal Equipment) and
DCE(Data Communications
Equipment)
Chapter 2 The Physical Layer
Chapter 2 The Physical Layer
27
2.5.1 Structure of the Telephone System
(a) Fully-interconnected network. (b) Centralized switch. (c) Two-level hierarchy.
计算机网络英文课件Chapter1
Introduction 1-11
client/server model
r r
peer-peer model:
r r
Network edge: connection-oriented service
Goal: data transfer
between end systems handshaking: setup (prepare for) data transfer ahead of time
Introduction 1-2
Chapter 1: roadmap
1.1 What is the Internet? 1.2 Network edge 1.3 Network core 1.4 Network access and physical media 1.5 Internet structure and ISPs 1.6 Delay & loss in packet-switched networks 1.7 Protocol layers, service models 1.8 History
protocols control sending,
receiving of msgs
r
router server local ISP
workstation mobile
e.g., TCP, IP, HTTP, FTP, PPP
Internet: “network of
networks”
r r
loosely hierarchical public Internet versus private intranet RFC: Request for comments IETF: Internet Engineering Task Force
client/server model
r r
peer-peer model:
r r
Network edge: connection-oriented service
Goal: data transfer
between end systems handshaking: setup (prepare for) data transfer ahead of time
Introduction 1-2
Chapter 1: roadmap
1.1 What is the Internet? 1.2 Network edge 1.3 Network core 1.4 Network access and physical media 1.5 Internet structure and ISPs 1.6 Delay & loss in packet-switched networks 1.7 Protocol layers, service models 1.8 History
protocols control sending,
receiving of msgs
r
router server local ISP
workstation mobile
e.g., TCP, IP, HTTP, FTP, PPP
Internet: “network of
networks”
r r
loosely hierarchical public Internet versus private intranet RFC: Request for comments IETF: Internet Engineering Task Force
计算机网络英文版课件1
Development of computer network
T
T
HOST
T
T
T
T
T
HOST
TTT
T
T
HOST CCP
T
T
H
T
T
C
CCP
T
HOST
T
T
CCP
C CommunicaCt
T
HOST
T T
ion subnet
H
H
T
T
T
T
Resource subnet
T
computer network vs. distributed system
Wide Area Networks(2)
❖A stream of packets from sender to receiver. ❖Store-and-forward (packet-switched): a packet
is stored in an intermediate router in its entirety, stored there until the required output line is free, and then forwarded.
❖ Software: This is what actually makes computer networks–not the hardware!
➢ Protocols: describe how two communicating parties exchange
information.
➢ Services: describe what a network offers to parties that want
计算机网络概论 英文版
• • • • • • Stream denotes a paradigm in which a sequence of bytes flows from one application program to another Internet's mechanism arranges two streams between a pair of communicating applications, one in each direction The network accepts input from either application, and delivers the data to the other application The stream mechanism transfers a sequence of bytes without attaching meaning to the bytes and without inserting boundaries A sending application can choose to generate one byte at a time, or can generate blocks of bytes The network chooses the number of bytes to deliver at any time
– However, understanding network protocols and technologies allows them to write efficient and reliable code that enables applications to scale across many sites
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved. 9
– However, understanding network protocols and technologies allows them to write efficient and reliable code that enables applications to scale across many sites
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved. 9
计算机网络原理英文版课件Chapter3
SP: 5775
DP: 80
D-IP:C
S-IP: B
Web Server Thread/subprocess
Chapter 3 outline
3.1 Transport-layer services 3.2 Multiplexing and demultiplexing 3.3 Connectionless transport: UDP 3.4 Principles of reliable data transfer rdt Model GBN（Go Back N） SR（Selective Repeat ）
UDP: User Datagram Protocol [RFC 768]
“best effort” service, UDP segments may be: lost delivered out of order to app connectionless: no handshaking between UDP sender, receiver each UDP segment handled independently of others
Connectionless demux (cont)
DatagramSocket serverSocket = new DatagramSocket(6428);
Client IP:B
9157
P2
client IP: A
P1
5775
P1
6428
P3
server IP: C
SP: 6428
DP: 9157
Connection-oriented demux (cont)
Client IP:B
9157
DP: 80
D-IP:C
S-IP: B
Web Server Thread/subprocess
Chapter 3 outline
3.1 Transport-layer services 3.2 Multiplexing and demultiplexing 3.3 Connectionless transport: UDP 3.4 Principles of reliable data transfer rdt Model GBN（Go Back N） SR（Selective Repeat ）
UDP: User Datagram Protocol [RFC 768]
“best effort” service, UDP segments may be: lost delivered out of order to app connectionless: no handshaking between UDP sender, receiver each UDP segment handled independently of others
Connectionless demux (cont)
DatagramSocket serverSocket = new DatagramSocket(6428);
Client IP:B
9157
P2
client IP: A
P1
5775
P1
6428
P3
server IP: C
SP: 6428
DP: 9157
Connection-oriented demux (cont)
Client IP:B
9157
计算机网络专业外语PPT
What is
the Computer Network Technically, Network is defined as "If at least one process in one computer is able to send/receive data to/from at least one process residing in a remote computer, then the two computers are said to be in network".
The Applications(应用 应用) 应用
A usenet newsgroup（新闻组） is
a repository usually within the Usenet system, for messages posted from many users in different locations. The term may be confusing to some, because it is usually a discussion group. Newsgroups are technically distinct from, but functionally similar to, discussion forums on the World Wide Web. News reader software is used to read newsgroups.
The Applications(应用 应用) 应用
---Video conferencing
The Applications(应用 应用) 应用
Voice over IP (VoIP网络电话) is a family of
计算机网络英文课件：1 Introduction
• new national networks: Csnet, BITnet, NSFnet, Minitel
• 100,000 hosts connected to confederation of networks
2020/12/7
Computer Networks -1-Part 1
5
Internet History
network for advanced research project agent of defense department, USA. • Internet: 1986 • National Information Infrastructure: 1993 • Commercialized Internet: 1995 • NGI: 1995, next generation internet • I2: 1996, Internet2 • CNGI: Cernet2 + …
– decentralized control define today’s Internet
architecture
2020/12/7
Computer Networks -1-Part 1
4
Internet History
1980-1990: new protocols, a proliferation of networks
• early 1990s: Web
– hypertext [Bush 1945, Nelson 1960’s]
– HTML, HTTP: Berners-Lee
– 1994: Mosaic, later Netscape – late 1990’s: commercialization
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1
Chapter 3
Internet Applications and
Network Programming
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
2
Topics Covered
• 3.1 Introduction • 3.2 Two Basic Internet Communication Paradigms • 3.3 Connection-Oriented Communication • 3.4 The Client-Server Model of Interaction • 3.5 Characteristics of Clients and Servers • 3.6 Server Programs and Server-Class Computers • 3.7 Requests, Responses, and Direction of Data Flow • 3.8 Multiple Clients and Multiple Servers • 3.9 Server Identification and Demultiplexing • 3.10 Concurrent Servers • 3.11 Circular Dependencies Among Servers • 3.12 Peer-to-Peer Interactions • 3.13 Network Programming and the Socket API
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
5
3.1 Introduction
• Internet application programmers can get started easily
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
3
Topics Covered
• 3.14 Sockets, Descriptors, and Network I/O • 3.15 Parameters and the Socket API • 3.16 Socket Calls in a Client and Server • 3.17 Socket Functions Used by Both Client and Server • 3.18 The Connection Function Used Only by a Client • 3.19 Socket Functions Used Only by a Server • 3.20 Socket Functions Used with the Message Paradigm • 3.21 Other Socket Functions • 3.22 Sockets, Threads, and Inheritance
– describes the conceptual paradigm that applications follow when they communicatesents the details of the socket Application Programming Interface (socket API) that Internet applications use
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
4
3.1 Introduction
• The Internet offers users a rich diversity of services
– none of the services is part of the underlying communication infrastructure
on computers attached to the Internet
• It is possible to devise new services without changing the Internet
• Chapter covers two key concepts of Internet applications:
Computer Networks and Internets, 5e By Douglas E. Comer
Lecture PowerPoints By Lami Kaya,
© 2009 Pearson Education Inc., Upper Saddle River, NJ. All rights reserved.
• It is possible to create Internet applications without knowing how networks operate
– However, understanding network protocols and technologies allows them to write efficient and reliable code that enables applications to scale across many sites
• Internet provides a general purpose mechanism on which
– all services are built – and individual services are supplied by application programs that run
• Later parts of the text provide the necessary information by explaining data communications and protocols used to form the Internet