GROUP 2Nurul Aminah Thaqif

Nurul Nadiah binti RamliAminah binti Mustaffa

Muhammad Thaqif bin Md Rajab

Chap 9:COMMUNICATIONS AND NETWORKS

Introduction

COMMUNICATIONS

COMMUNICATION CHANNELS

-Twisted-pair cable-Coaxial cable

-Fiber-optic cable

-Radio frequency-microwave

-satellite-infrared

COMMUNICATION CHANNELSCHANNEL DESCRIPTION

Twisted pair Twisted copper wire,used for standard telephone lines and Ethernet cables.

Coaxial cable Solid copper core,more than 80 times the capacity of twisted pair.

Fiber-optic cable Light carries data ,more than 26,000 times the capacity of twisted pair.

Radio frequency Radio waves connect wireless devices including cell phones and computer components.

Microwave High-frequency radio waves ,travels in straight line through the air.

Satellite Microwave relay station in the sky ,used by GPS devices.

Infrared Infared light travels in a straight line.

CONNECTION DEVICES

-modula-demodulator.-Modulation: Process of converting digital to analog and demodulation is vice versa.-Enable digital microcomputers to communicate across different media,including telephone wires, cable lines, and radio waves.

-For years, individuals relied on dial-up services using existing telephones and telephone modems to connect to internet. This type of service has been replaced by higher-speed connection services including DSL,cable,satellite, and cellular services.

MODEMS

TYPES:-Telephone modem

-DSL(digital subscriber line)-Cable modem

-Wireless modem

CONNECTION SERVICE

TYPES:-Digital subscriber line(DSL) service

-Cable service-Satellite connection service

-cellular service

Description types of modemsTelephone modem-Used to connect a computer directly to a telephone line.-internal : system board –external : system unitDSL(digital subscriber line) modem-Uses standard phone lines to create a high- speed connection directly to phone

company’s offices.(usually external-connect to system unit using USB or Ethernet ports.

Cable modem-Uses the same coaxial cable television.-creates high- speed connections like DSL using system unit’s USB or Ethernet port. Wireless modem-Known as WWAN(wireless wide area network).- Usually plug-in USB or ExpressCard device that provides very portable high-speed

connectivity.

Description of Connection ServiceDigital subscriber line(DSL) service-Provided by telephone companies using existing telephone lines to provide

high-speed connections.Example:ADSL(asymmetric digital subscriber line)-faster than dial-upCable service-Provided by cable television companies using their existing television cables-

faster than DSLSatellite connection services-Use satellite to provide wireless connections-slower than DSL and cable

modems-but are available almost anywhere using satellite-receiving disk.Cellular services -3G or 4G to provide wireless connectivity to the internet-not fast as the other

services but are rapidly growing in popularity for mobile devices(phones and other portable devices.

DATA TRANSMISSION

Measurement of the width or capacity of the communication channel.

Voiceband Medium band Broadband Baseband

DATA TRANSMISSION

A set of communication rules for the exchange of information.

Identification Packetization

NetworksA communication system that connects two or more computers so

that they can exchange information and share resources.

TERM DESCRIPTION

NODE Device that is connected to a network. It could be a computer, printer, or data storage device

Clients A node that requests and uses resources available from other nodes. Typically, a client is a user’s microcomputer.

Server A node that shares resources with other nodes.

Directory server A specialized server that manages resources ,such as user accounts, for an entire network.

Host Any computers system that can be accessed over a network.

Switch Central node that coordinates the flow of data by sending messages directly between sender and receiver nodes.

(NIC) Network interface cards

Expansion cards located within the system unit that connect the computer to a network -LAN adapter

(NOS) Network operating system

Control and coordinate the activities of all computers and other devices on network.

Network administration

A computer specialist responsible for efficient network operations and implementation of new networks.

NETWORK ARCHITECTURE

Describe how network is arranged and how resources are coordinated and

shared.

TOPOLOGIES

Describe the physical arrangement of the network.

• Star network -each device is connected directly to a central network switch.

•Tree/hierarchical network –each device is connected to a central node, either directly through one or more other devices.

• Mesh network -each device connected to more than one other device

STRATEGIES

Define how information and resources are shared

Strategy Description

Client/servernetworks

Clients request services; server provide services and coordination; efficient network management software; expensive.

Peer-to-peernetworks

All nodes act as clients and servers ;easy and inexpensive; lacks security controls.

Organizational NetworksInternet Technologies

Intranet-private network within an organization that resembles the internet.-use browsers, Web sites, and Web pages

Extranet-private network that connects more than one organization.-to allow suppliers and others limited accesses to their networks.-to increase efficiency and reduce costs.

Network Security

Firewall-consists of hardware and software that control access to a company’s intranet and other internal networks.

Intrusion detection system (IDS)-work with firewalls to protect an organization’s network.

Virtual private networks(VPN)-create secure private connection between a remote user and an organization’s internal network.

Careers in IT

Network administrators -manage company’s LAN and WAN networks.-responsible for design, implementation, and maintenance of networks-Responsibilities include maintenance of both hardware and software related to a company’s intranet and Internet networks.