Computer Networks: Interoperability and Types - Prof. Tracy Maples, Study notes of Computer Science

An introduction to computer networks, their history, types, and motivations. It covers wans (e.g., arpanet, internet) and lans (ethernet, fddi, novell netware, appletalk, wireless), as well as other networks like telephone, cable tv, satellites, man, san, and pan. The document also discusses connectivity, link types, and switched networks (circuit-switched and packet-switched).

Typology: Study notes

Pre 2010

Uploaded on 08/17/2009

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CECS 474 Computer Network
Interoperability
INTRODUCTION
“May you live in interesting
times.”
-- Chinese Blessing (or Curse)
The Industrial Revolution (c. 1760)
The change in social and economic organization resulting from
the replacement of hand tools by machine and power tools and the
development of large-scale industrial production.
The “Digital Revolution” (c. 1990)
The change in social and economic organization resulting from
the replacement of earlier forms of communication and
information storage by a digital format and the development of
large-scale networks transmitting digital information.
Introduction to Networking
net·work (net´würk´) n. 1. any arrangement or fabric of parallel
wires, threads, etc. crossed at regular intervals by others fastened to
them so as to leave open spaces; netting; mesh 2. a thing resembling
this in some way; specif., a) a system of roads, canals, veins, etc. that
connect with or cross one another b) Radio and TV a chain of
transmitting stations controlled and operated as a unit c) a group,
system, etc. of interconnected or cooperating individuals 3. the making
of nets or netted fabric
Dr. Tracy Bradley Maples (Spring 2009)
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CECS 474 Computer Network

Interoperability

INTRODUCTION

“May you live in interesting

times.”

-- Chinese Blessing (or Curse) The Industrial Revolution (c. 1760) The change in social and economic organization resulting from the replacement of hand tools by machine and power tools and the development of large-scale industrial production. The “Digital Revolution” (c. 1990) The change in social and economic organization resulting from the replacement of earlier forms of communication and information storage by a digital format and the development of large-scale networks transmitting digital information.

Introduction to Networking

net·work (net´würk´) n. 1. any arrangement or fabric of parallel wires, threads, etc. crossed at regular intervals by others fastened to them so as to leave open spaces; netting; mesh 2. a thing resembling this in some way; specif., a) a system of roads, canals, veins, etc. that connect with or cross one another b) Radio and TV a chain of transmitting stations controlled and operated as a unit c) a group, system, etc. of interconnected or cooperating individuals 3. the making of nets or netted fabric

Defn : A computer network is a collection of computers interconnected via a transmission medium (e.g., copper wire, optical fiber, microwaves, satellites, etc.) The computers are usually general-purpose programmable hardware devices.

Allow humans to communicate through email, telephone, teleconferencing, etc.

History of Networking

WANs (c. 1970) Driving force: The need for government and university researchers located in various parts of the United States to communicate ideas and data between computers. Examples:  ARPANET was created in the early seventies  Funded by ARPA (DARPA)  Prototype for what has evolved into the Internet  Created by folks from Berkeley, MIT, AT&T Bell Labs, etc. LANs Driving force: The creation of the personal computer in the mid- 70s and its widespread usage in the mid-80s. Evolution:

Sneaker Net  Data Switches  Disk Servers  File Servers

Switched Networks

Two types of switched networks:

  1. Circuit-switched networks provide service by setting up a total path of connected links from the origin to the destination host. A control message is first sent to setup a path from the origin to the destination. (A return signal informs the origin that data transmission may proceed.) Once data transmission starts, all channels in the path are used simultaneously, and the entire path remains allocated to the transmission (whether or not it is in use).
  2. Packet-switched networks decompose messages into small pieces called packets. These packets are each numbered and make their way through the net in a store-and-forward fashion. Links are considered busy only when they are currently transmitting packets.

Switching Performance Issues

Header overhead (i.e., the amount of "extra" information that must be sent along with the data to ensure proper transmission) For large amounts of data: circuit switching <= packet switching Transmission delay (i.e., the amount of time it takes data from the time it enters the network until it arrives at its' destination)  For short and bursty messages: packet switching has the lowest delay.

 For long, continuous streams of data: circuit switching has the lowest delay.