Download CS412 Computer Networks - Winona State University

CS 313 Introduction to
Computer Networking &
Telecommunication
Introduction – Part I
Chi-Cheng Lin, Winona State University
Topics
Introduction
 Metric Units
 Network Hardware
 Network Software
 Reference Models
 Example Networks
 Standards and Standards Organizations

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Introduction

First two decades of computing
Highly centralized computer systems

Now
A large number of SEPARATE but
INTERCONNECTED computers
 Computer networks
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What is Computer Network?

An collection of AUTONOMOUS
computers INTERCONNECTED by a
single technology
Interconnected: Able to EXCHANGE
INFORMATION via transmission media
Media: copper wire, fiber optics, microwaves,
communication satellites
Autonomous: no master/slave relation
NOT autonomous:
 One computer can control another one
 e.g., a large computer with remote printers and
terminals

Network of networks: internetwork
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What is Telecommunication?

What is data communication?
Exchange of data between two devices via
some form of transmission media
Data are represented by bits – 0s and 1s

What is telecommunication?
Exchange of information over distance
using electronic equipment
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What is Telecommunication?

Components of data communication
Sender, receiver, medium, message, and
Protocol: set of rules governing data
communication

Key elements of a protocol
Syntax
Structure/format
Semantics
Meaning
Timing
When and how fast
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Data Communication

Components of data communication
Protocol
Step 1: …
Step 2: …
:
Protocol
Step 1: …
Step 2: …
:
Message
Sender
Medium
Receiver
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Distributed System vs. Computer Network

Distributed system
TRANSPARENCY
A collection of independent computers appear
as a single coherent system
Single model/paradigm to users
Middleware on top of OS
Example?

Computer network
No such coherence, model, middleware
Machines visible to users
Users log onto remote machines
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Distributed System vs. Computer Network
A distributed system is a SOFTWARE
system built on top of a network
 Distinction between network and
distributed system

Software (especially OS) rather than
hardware

However, considerable overlap between
the two subjects
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Uses of Computer Networks

Business applications
Resource sharing
Communication medium
E-commerce

Client-server model
 Client requests, server performs & then replies
 Example?
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Business Applications of Networks

A network with two clients and one
server.
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Client-Server Model
1
2
3
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Uses of Computer Networks

Home applications
Access to remote information
On-line publishing, digital library, WWW
Person-to-person communication
Email, instant messaging, videoconferencing,
Internet phone, E-learning, multi-person messaging
Interactive entertainment
Video on demand (VOD), games
E-commerce
Home shopping, electronic banking and investment,
on-line auction
Social network applications
Collaborative content creation
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Home Network Applications (2)

Besides client-server model
Peer-to-peer system: there are no fixed
clients and servers.
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Mobile Users






Notebooks, PDAs, cellular phones
Smart phones: convergence of telephones and
Internet
M-commerce, texting
Sensor networks
Wearable computers
Wireless networking and mobile computing
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Metric Units

The principal metric prefixes
b: bit
 B: byte = 8 bits

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Metric Units

Computer storage size power of 2
mega = 220=1,048,576
1 MB = 1 mega bytes = 1,048,576 bytes
1 GB =

Computer networking speed not power of 2
mega = 106 =1,000,000
1 Mbps = 1 mega bits per second
= 1,000,000 bits / sec
1 Gbps =
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