Introduction
1-1
Chapter 1
Computer Networks and the Internet
Lecturer: Yun Liu
138********
liuyunkm@https://www.doczj.com/doc/bd12546873.html,
https://www.doczj.com/doc/bd12546873.html,
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Marks
Home Works:10%
Projects:20%
Exam:70%
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中文参考书
计算机网络:用自顶向下方法描述因特网特色:第2版
作者:[美]James F.Kurose Keith W.Ross
出版社:人民邮电出版社
出版日期:2004-01-01 ISBN:711511942英文原版教程
计算机网络——自顶向下方法与Internet特色（第三版影印版）作者:James F.Kurose
出版社:高等教育出版社
出版日期:2005-01-01
ISBN:704012231
Introduction 1-4
Chapter 1: Introduction
Our goal:
get context, overview, “feel”of networking
more depth, detail later in course
approach:
descriptive
use Internet as
example Overview:
what’s the Internet
what’s a protocol?
network edge
network core
access net, physical media
Internet/ISP structure
performance: loss, delay
protocol layers, service models history
Introduction1-5
Chapter 1: roadmap
1.1 What is the Internet?
1.2Network edge
1.3Network core
1.4 Network access and physical media
1.5Internet structure and ISPs
1.6Delay & loss in packet-switched networks 1.7Protocol layers, service models
1.8History
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Introduction
1-8
“Cool”
internet appliances
World’s smallest web server
https://www.doczj.com/doc/bd12546873.html,/~shri/iPic.html
IP picture frame
https://www.doczj.com/doc/bd12546873.html,/
Web-enabled toaster+weather forecaster
Chapter 1: roadmap
1.1 What is the Internet?
1.2 Network edge
1.3Network core
1.4 Network access and physical media
1.5Internet structure and ISPs
1.6Delay & loss in packet-switched networks 1.7Protocol layers, service models
1.8History
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Network edge: connection-oriented service
Goal:data transfer between end systems
handshaking:setup (prepare for) data transfer ahead of time
Hello, hello back human
protocol
set up “state”in two
communicating hosts
TCP -Transmission Control Protocol
Internet’s connection-
oriented service TCP service[RFC 793]
reliable, in-order byte-stream data transfer
loss: acknowledgements
and retransmissions
flow control:
sender won’t overwhelm
receiver
congestion control:
senders “slow down sending
rate”when network
congested
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Network edge: connectionless service
Goal:data transfer between end systems
same as before!
UDP-User Datagram Protocol [RFC 768]: Internet’s connectionless service
unreliable data
transfer
no flow control
no congestion control App’s using TCP:
HTTP (Web), FTP (file transfer), Telnet (remote login), SMTP (email)
App’s using UDP:
streaming media, teleconferencing, DNS, Internet telephony
Introduction1-17
Chapter 1: roadmap
1.1 What is the Internet?
1.2Network edge
1.3 Network core
1.4 Network access and physical media
1.5Internet structure and ISPs
1.6Delay & loss in packet-switched networks 1.7Protocol layers, service models
1.8History
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