计算机网络英文版课件1.ppt

workChapter 1Introduction
郭斌
E_mail: jxnuit@
Topics
What works
Uses ponents works
Reference Model works
Basic Concepts of Data Transmission
What work
Collection of puters interconnected by a single technology.
The old model of a puter serving all of anization'putational needs has been replaced by one in which a large number of separate but puters do the job.
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Resource
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Development work
work vs. distributed system
The key distinction is that in a distributed system, a collection of puters appears to its users as a single coherent system.
A distributed system is a software system built on top of work. The software gives it a high degree of cohesiveness and transparency.
Thus, the distinction between work and a distributed system lies with the software (especially the operating system), rather than with the hardware.
Uses works
Business Applications
Resource Sharing
E-mail
Videoconferencing
merce
Home Applications
Access to remote information
Person-to-munication
Interactive entertainment
merce
Access to remote information
surfing the World Wide Web for information or just for fun.
Many newspapers have gone on-line and can be personalized.
on-line digital library.
Person-to-munication
E-mail
instant messaging
chat room
News groups
peer-to-munication
Interactive entertainment
video on demand
game playing
merce
home online shopping
access to financial institutions
electronic flea markets (e-flea)
client-server model
peer-to-peer Model
In peer-to-peer system there are no fixed clients and servers.