Computer Networks: Understanding Different Types, Topologies, and Protocols, Slides of Introduction to Computing

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CS101 Introduction to Computing

Lecture 27

Computer Networks

During the last lecture … (Web Design for Usability)

• We looked at the role of usability in Web design
• We identified some of the factors affecting the usability of a Web page

think roadside billboard

rather than Dewan-e-Ghalib

Designs should be

consistent &

predictable

(unified)

Website Navigation

• The interface/controls that a Website provides to the user for accessing various parts of the Website
• It probably is the most important aspect of the design of a Website

Good designs assist

the user in

recovering from

errors

All of you have used

computer networks.

What is a

computer network?

Computer Network

Multiple computers that are connected together to share information and other resources

13

Computer C

Computer D

Computer

Computer^ E A

Computer B

Hub

Example of a Computer Network

Components of Conventional Computer Networks

1. Computers
2. Network Interface Cards (NIC)
   • I/O device that plugs into the computer
   • Enables it to communicate over a network
3. Hub
   • The network traffic controller

How Does a Conventional Network Work?

1. Suppose computer A wants to send a message to D
2. Computer A sends the message to its NIC
3. The NIC translates the message into electrical pulses suitable for the computer network in use & transmits it to the hub through the cable

How Does a Conventional Network Work?

4. The hub receives them and forwards them to all computers connected to the it
5. The NICs of all computers connected to the hub receive the forwarded electrical pulses
6. The NIC of computer D decides that the message is for it, & translates the pulses back to a form suitable for the computer

Hub (2)

• Each computer in a network is connected to one of those ports through a cable
• A computer wanting to send a message to one of the others in the network sends a message to the hub, which, in turn, broadcasts the message to all others connected to it

Packet (1)

• The smallest unit of data transmitted over a computer network
• A message to be transferred over the network is broken up into small packets by the sending computer
• Each packet contains the following info:
  • Sender's address
  • Destination address
  • Data
  • Error-recovery info (^) Docsity.com^20