Chapter 1: Computer
Networks
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
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Basic Networking Concepts

Computer network
Set of independent computer systems connected
by telecommunication links



Purpose: Sharing information and resources
Nodes, hosts, or end systems

Individual computers on a network
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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 the
caller and callee


Analog medium
Requires modem at both ends to transmit
information produced by a computer


Computer produces digital information
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Communication Links (continued)

Dial-up phone links


Transmission rate: 56,000 bps (56 Kbps)
Broadband
Transmission rate: Exceeding 256,000 bps (256
Kbps)

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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

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Transmission Time of an Image at Different Transmission Speeds
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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
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Local Area Networks

Local area network (LAN)
Connects hardware devices that are in close
proximity


The owner of the devices is also the owner of the
means of communications

Common wired LAN topologies

Bus

Ring

Star
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Figure 1.4
Some Common
LAN Topologies
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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
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An Ethernet LAN Implemented
Using Shared Cables
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Figure 7.6
An Ethernet LAN Implemented Using a Hub
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Wide Area Networks

Wide area networks (WANs)
Connect devices that are across town, across the
country, or across the ocean

Users must purchase telecommunications
services from an external provider


Dedicated point-to-point lines
Most use a store-and-forward, packet-switched
technology to deliver messages

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Typical Structure of a Wide Area Network
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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.