Chapter 1: ComputerNetworks

IB 300: Advanced Computer

Sciences.

Professor: Nabil Elmjati

Introduction

Computer network

Computers connected together

Purpose: Exchanging resources and information

Just about any kind of information can be sent

Examples: Television and radio signals, voice,graphics, handwriting, photographs, movies

3

Basic Networking Concepts

Computer network

Set of independent computer systems connectedby telecommunication links

Purpose: Sharing information and

resources

Nodes, hosts, or end systems Individual computers on a network

4

Basic Networking Concepts

Node: A Node is a connection point. In a physical Network, it is an electronic device that is attached to a network and is capable of sending, receiving and forwarding information over a communication channel (Network)

Host: Any Computer connected to a network is considered a host.

Communication Links

Switched, dial-up telephone line

A circuit is temporarily established between thecaller and callee

Analog medium

Requires modem at both ends to transmitinformation produced by a computer

Computer produces digital information

5

6

Communication Links (continued)

Dial-up phone links

Transmission rate: 56,000 bps (56 Kbps)

Broadband

Transmission rate: Exceeding 256,000 bps (256Kbps)

8

Communication Links (continued)

Options for broadband communications

Home use

Digital subscriber line (DSL)

Cable modem

Fiber Optics

Commercial and office environment

Ethernet

Fast Ethernet

Gigabit Ethernet

9

Transmission Time of an Image at Different Transmission Speeds

10

Communication Links (continued)

Wireless data communication

Uses radio, microwave, and infrared signals

Enables “mobile computing”

Types of wireless data communication

Wireless local access network

Wireless wide-area access network

11

Local Area Networks

Local area network (LAN)

Connects hardware devices that are in closeproximity

The owner of the devices is also the owner of themeans of communications

Common wired LAN topologies

Bus

Ring

Star

12

Figure 1.4

Some CommonLAN Topologies

13

Local Area Networks (continued)

Ethernet

Most widely used LAN technology

Uses the bus topology

Two ways to construct an Ethernet LAN

Shared cable

Hubs: The most widely used technology

14

An Ethernet LAN ImplementedUsing Shared Cables

15

Figure 7.6

An Ethernet LAN Implemented Using a Hub

16

Wide Area Networks

Wide area networks (WANs)

Connect devices that are across town, across thecountry, or across the ocean

Users must purchase telecommunicationsservices from an external provider

Dedicated point-to-point lines

Most use a store-and-forward, packet-switchedtechnology to deliver messages

17

Typical Structure of a Wide Area Network

18

IP Address

What is an IP Address: An Internet Protocol address (IP

address) is a numerical label assigned to each device (e.g., computer, printer) that is part of a Computer Network.

Example of IP address: 192.168.1.1 There are two types of IP addresses: Static

and Dynamic.

Static vs Dynamic

Static IP: A fixed IP that is permanently assigned to a host.

Dynamic IP: A temporary IP that expires when the host goes offline, and changes the next time the host connects to the network.

How to know your IP address?

Local IP Address: By running the CMD command in windows and typing: “ipconfig” in the terminal, then hitting enter.

Public IP (given by the ISP): You can either visit a site such as http://whatismyipaddress.com/Or access your router to find out the actual IP address.