Chapter 1 Introduction

Bus (a) Ring (b)

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Metropolitan Area Networks

A metropolitan area network based on cable TV
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Home Applications of Networks (3)

Some forms of e-commerce
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Mobile Network Users

Combinations of wireless networks and mobile computing
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Home Applications of Networks
Access to remote information Person-to-person communication Interactive entertainment Electronic commerce
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Transmission Technologies

Broadcast transmission
Usually smaller, geographically localized networks Most applicable: local area networks


Point-to-point transmission

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Reference Models (2)

Protocol layering is the main structuring method used to divide up network functionality
• Each protocol layer talks virtually to its peer • Each layer communicates only through the one below • Lower layer services are accessed through an interface • At bottom, messages are carried by the medium

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Network Software (2)

Protocol hierarchies
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Network Software (3)

Information flow that supports communication at layer 5

Microwave, refrigerator, clock, furnace, air-condition unit
Utility meter, burglar alarm, babycam
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Telemetry

Network Software
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Personal Area Networks

A Bluetooth-based PAN configuration
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Local Area Networks

Two broadcast networks
Computer Networks
Prof. Jingsha He School of Software Engineering Beijing University of Technology
Chapter 1 Introduction
Definitions

Computer network
A number of individual computers interconnected through a communication network A collection of autonomous computer systems interconnected using a single technology
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Wide Area Networks (5)

A stream of packets from sender to receiver
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Wireless Networks
Protocol hierarchies Design issues for the layers Connection-oriented and connectionless services Service primitives Relationship between services and protocols
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Services to Protocols Relationship

Relationship between a service and a protocol
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Reference Models
The OSI Reference Model The TCP/IP Reference Model A comparison of OSI and TCP/IP A critique of the OSI model and protocols A critique of the TCP/IP reference model


Computer network vs. distributed system

Distributed system
A
abstraction for computation or data processing
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Uses of Computer Networks
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Service Primitives (2)

A simple client-server interaction using acknowledged datagrams
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Social Issues
Politics Religion Pornography The right of individuals Copyright Security Privacy

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Computers

Desktop PC, PDA, shared peripherals
Entertainment

TV, DVD, VCR, camera, stereo, MP3
Telephone, cell phone, intercom, fax
Telecomm

Appliances

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Home Applications of Networks (2)

No fixed clients and servers in a peer-to-peer system
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Wireless Networks (3)
Individual mobile computFra Baidu bibliotekrs (a) A flying LAN (b)

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Home Network Components
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Connection-Oriented and Connectionless Services

Six different types of service
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Service Primitives

Six service primitives for implementing simple connection-oriented services
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Wide Area Networks

WAN that connects three branch offices in Australia
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Wide Area Networks (2)

WAN using a virtual private network
Network Hardware
Local area networks Metropolitan area networks Wide area networks Wireless networks Home networks Internetworks

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Design Issues for the Layers
Addressing Error control Flow control Multiplexing Routing

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Categories of wireless networks
System interconnections Wireless LANs Wireless WANs

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Wireless Networks (2)
Bluetooth configuration (a) Wireless LAN (b)
Business applications Home applications Mobile users Social issues


As the result of the various uses and wide applications of computer networks
Usually large networks Most applicable: wide area networks

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Classification of Networks

Scale of processor interconnections
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Wide Area Networks (3)

WAN using an ISP network
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Wide Area Networks (4)

Relation between hosts on LANs and the subnet
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Business Applications of Networks
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Business Applications of Networks (2)

The client-server model that involves requests and replies