Computer network & communication answer

Computer network & Computer network & communicationcommunication

Computer networkComputer network is a system of interconnected is a system of interconnected

computers & peripheral devices. eg: computers & peripheral devices. eg: it may connect computer, printer, it may connect computer, printer,

scanners and cameras.scanners and cameras.

Communications Communications is about the transfer of information is about the transfer of information from a sender, across a distance, to from a sender, across a distance, to

a receiver.a receiver.

Physical mediumPhysical medium

Cable Cable wire wire Atmosphere Atmosphere

Information can be transmitted:Information can be transmitted: texttext Voice/ sound Voice/ sound Image/ graphic Image/ graphic video video

Transmit information / dataTransmit information / data

analogue signal - telephones , radios analogue signal - telephones , radios

digital signal – computers digital signal – computers

Analogue signal Digital signal

Signal translator – MODEMSignal translator – MODEM

Modem – short form of Modulator or Demodulator Modem – short form of Modulator or Demodulator Functions: converts digital signal into analogue Functions: converts digital signal into analogue

and and back again into digital signal for back again into digital signal for information to move across the information to move across the telephone line.telephone line.

Connections for networkingConnections for networking a physical medium a physical medium Protocols Protocols System application System application

Failure of communicationsFailure of communications

physical medium is cut off.physical medium is cut off. protocol between interconnected is protocol between interconnected is

not same. not same.

Protocol : is a set of rules or standard Protocol : is a set of rules or standard designed so that computers can designed so that computers can exchange information with a minimal exchange information with a minimal errors.errors.

Advantages of networking Advantages of networking

can shared data can shared data can shared resources can shared resources can exchange information can exchange information can sharing devices or softwarecan sharing devices or software can communicate with each others.can communicate with each others.

Components of communications Components of communications

hardwarehardware softwaresoftware

-computers-computers- hub- hub

-switch -switch -router -router- NIC - NIC -wired -wired

-wireless -wireless

-operating-operatingSystemSystem

- applications- applications “ google, yahoo, msn”“ google, yahoo, msn”

Types Network communication Types Network communication channels channels

twisted pair wire twisted pair wire coaxial cable coaxial cable fibre-optic cable fibre-optic cable satellite systems satellite systems wireless systems (namely using wireless systems (namely using

radio waves, microwaves, and radio waves, microwaves, and infrared)infrared)

Network Interface Card (NIC)Network Interface Card (NIC)

NIC provides connection between NIC provides connection between the computer & the network the computer & the network communication media.communication media.

to move data from the PC’s system to move data from the PC’s system to the network medium.to the network medium.

able the networking devices work able the networking devices work properly. properly.

Importance of Network & Importance of Network & CommunicationsCommunications

E-business

To conduct business transactions on The internet. Including online Shopping, selling and renting.

Online Education

Students at any location around the World can participate in an online

Classroom, download tutorial Questions & submit their

assignments.

E-banking

It handles all types of banking transactions such as account Management, fund transfer,

Payments Bills, check account balance….

Long Distance Communication

Cheaper, faster and more effective(video conference meeting)

Types of networks Types of networks

Metropolitan Area Network(MAN)

• KL City

Local Area Network (LAN)

• SMK KL

Wide Area Network (WAN)

• Between KL & London

Local Area Network (LAN)

smallest network.smallest network. single building, home, school.single building, home, school. simplest form of LAN is to connect simplest form of LAN is to connect

two computers together.two computers together. less than 500 interconnected devices.less than 500 interconnected devices. inexpensive hardware: twisted pair, inexpensive hardware: twisted pair,

coaxial cable, fiber optic or wireless.coaxial cable, fiber optic or wireless. faster than MAN and WAN.faster than MAN and WAN.

Metropolitan Area Network(MAN)

Cities: Kuala Lumpur, Manila, Cities: Kuala Lumpur, Manila, Singapore, Singapore,

Tokyo, London and New York. Tokyo, London and New York. Large physical area : cityLarge physical area : city Example: bankExample: bank MAN used fiber optic.MAN used fiber optic. High speed network (not fast as LAN).High speed network (not fast as LAN).

Wide Area Network (WAN)

Largest network in the world Largest network in the world Cover large distances such as states, Cover large distances such as states,

countries or continents.countries or continents. WAN is group of MANs and LANs WAN is group of MANs and LANs Use Router to connect between Use Router to connect between

networks.networks. WAN use fiber optic, speed 20-WAN use fiber optic, speed 20-

2000kbps (slower than LAN and MAN). 2000kbps (slower than LAN and MAN).

Differences between types of Differences between types of networknetwork

Criteria Criteria LANLAN MANMAN WANWAN

CostCost Low Low High High Higher Higher

Network sizeNetwork size Small Small Larger Larger Largest Largest

SpeedSpeed Fasters Fasters Slower Slower Slowest Slowest

Transmission Transmission media type media type

Twisted pair Twisted pair Twisted pair Twisted pair & fiber optic & fiber optic cablecable

Fiber optic, Fiber optic, satellite, satellite, radio wave radio wave

No. of No. of computers.computers.

Smallest Smallest Large Large Largest Largest

Types of Network Architecture Types of Network Architecture Network architecture is the overall design of computer Network architecture is the overall design of computer

network that describes how a computer network network that describes how a computer network configured and what strategies are being used. configured and what strategies are being used.

Client- Server Network Peer to Peer Network

Def: Is a network in which the shared files and Def: Is a network in which the shared files and application application

are stored in the server but network users (clients) are stored in the server but network users (clients) can can

still store files on their individual PCs.still store files on their individual PCs.

Server : Sometimes called Server : Sometimes called host computerhost computer.. Server is a computer that provides services Server is a computer that provides services to other computers called clients. to other computers called clients. Functions Server: i) Control access to the hardware, Functions Server: i) Control access to the hardware, software and other resources on the software and other resources on the network.network. ii) Centralized storage area for ii) Centralized storage area for

programs, programs, data and information. data and information. Dedicated Server: Perform specific tasks, eg: file server, Dedicated Server: Perform specific tasks, eg: file server, printer server, database server and printer server, database server and network server. network server.

Client- Server Network

Peer 2 Peer Network (P2P)Peer 2 Peer Network (P2P)

Is a network with all the nodes acting as Is a network with all the nodes acting as both server and clients. both server and clients.

Have equal responsibilities and Have equal responsibilities and capabilities to use the resources available capabilities to use the resources available on the network.on the network.

No server is needed, each computer in the No server is needed, each computer in the network is called a peer. network is called a peer.

Differences between client-server Differences between client-server and peer to peer and peer to peer

Client –serverClient –server Peer to peer Peer to peer

Server control ability Server control ability while client don’t while client don’t

All computers have All computers have equal abilityequal ability

High costHigh cost Cheaper costCheaper cost

Use small and large Use small and large network network

Small networks Small networks

Easy to manage Easy to manage Hard to manage Hard to manage

3 types of network toplogies3 types of network toplogies

Bus TopologyBus Topology Consists of single central cable Consists of single central cable (Backbone).(Backbone). All nodes are share the backbone to communicate with All nodes are share the backbone to communicate with

each other on the network. each other on the network. No or 1 server is needed on the network.No or 1 server is needed on the network.

Advantages: i) easy implementationAdvantages: i) easy implementation ii) failure of the node doesn’t affect the ii) failure of the node doesn’t affect the entire LAN.entire LAN. Disadvantages: i) If the backbone fails, the entire bus Disadvantages: i) If the backbone fails, the entire bus network will be affected.network will be affected. ii) Network speed decreases when no. ii) Network speed decreases when no.

of nodes increases. of nodes increases. iii) Troubleshooting is difficult. iii) Troubleshooting is difficult.

Ring TopologyRing Topology

All computer & devices are connect in a loop.All computer & devices are connect in a loop. Can be found in the LAN.Can be found in the LAN. Have Server.Have Server.

Advantages: i) troubleshooting is easyAdvantages: i) troubleshooting is easy Disadvantages: i) If one node fail to function, Disadvantages: i) If one node fail to function, the network will fail to function.the network will fail to function. ii) Implementation is difficult.ii) Implementation is difficult. iii) speed decreases when the iii) speed decreases when the no. of nodes increases.no. of nodes increases.

Star topologyStar topology All computers are connected to a centralized All computers are connected to a centralized

mainframe computer.mainframe computer. Consists of central host and all nodes are Consists of central host and all nodes are

connect to a host.connect to a host. The host as a server, hub or router.The host as a server, hub or router. The host will control the flow of communication The host will control the flow of communication

in the network.in the network.

Advantages: i) easy implementAdvantages: i) easy implement ii) failure of a node doesn’t affect ii) failure of a node doesn’t affect the entire LAN.the entire LAN.

Disadvantages: i) If the host fails, the entire LAN Disadvantages: i) If the host fails, the entire LAN will will

be affected.be affected. ii) troubleshooting is difficult. ii) troubleshooting is difficult.

Differences of network topologies Differences of network topologies Bus topologyBus topology Ring Ring

topologytopologyStar topologyStar topology

Structure Structure Single Single central cable central cable (backbone)(backbone)

Connected in Connected in the loop the loop (circle)(circle)

Central hostCentral host

Host Host existence existence

Depends on Depends on the network the network

Depend on Depend on the network the network

Yes Yes

Connection Connection between between nodes nodes

No No connectionconnection

Yes Yes No No connectionconnection

Host failure Host failure Network still Network still can run can run

Network will Network will failfail

Network will Network will fail.fail.

Node failure Node failure Network still Network still can run can run

Network will Network will failfail

Network will Network will failfail

Common Network StandardsCommon Network Standards 802.3 (Ethernet LAN)802.3 (Ethernet LAN) 802.7 (Broadband LAN)802.7 (Broadband LAN) 802.8 (Fibre-optic LAN and MAN)802.8 (Fibre-optic LAN and MAN) 802.11 (Wireless LAN)802.11 (Wireless LAN)

ProtocolsProtocols Protocols provide the rules on how computers Protocols provide the rules on how computers

communicate. They define how devices communicate. They define how devices intercommunicate in a network environment.intercommunicate in a network environment.

Some types of protocols: Some types of protocols:

i) Hypertext Transfer Protocols (HTTP)i) Hypertext Transfer Protocols (HTTP)

ii) Simple Mail Transfer Protocol (SMTP)ii) Simple Mail Transfer Protocol (SMTP)

iii) File Transfer Protocol (FTP)iii) File Transfer Protocol (FTP)

iv) Transmission Control Protocol (TCP)iv) Transmission Control Protocol (TCP)

3 Types of network communication 3 Types of network communication technologytechnology

Internet

• largest computer network• usages of internet:

-Information, research & exchange-Commerce

-Real time communication- banking -Shopping

-Entertainment - education

-Gaming

Intranet

• internal network • within an organization,

2 buildings, cities, states.. Usages of intranet:

-Telephone directories - event calendars

- employee handbook- job posting

- staff information

Extranet

• private network that Uses Internet technology

and public TelecommunicationSystem to securely

Share relevant information With authorized parties.

Intranet Intranet InternetInternet

Internal Internal network network

Global Global information information

Within an Within an organization organization

Various Various

OrganizatioOrganizationsns

Internet Internet Extranet Extranet

Uses Uses internet internet

technologytechnology

Uses Uses intranet intranet

technologytechnology

Serves Serves everybodyeverybody

Serves Serves enterprise enterprise

(customer & (customer & suppliers)suppliers)

With/ With/ without without firewallfirewall

With firewallWith firewall

Low Low securitysecurity

Tight Tight securitysecurity

Communication devicesCommunication devices Network Interface Card Wireless Network Interface

Card

• allow the computers to communicate over a computer network.

• connects to a radio-based computer network.• uses an antenna to communicate through microwaves.•Operates in 2 modes: i) Infrastructure Mode ii) Hoc Mode

Communication devicesCommunication devices Hub/ switch

• enables a computer to transmit data over telephone or cable lines.

• to connect segments of LAN • Hub contains multiple ports.

Modem

Communication devicesCommunication devices Wireless Access

Point

• Device that forwards data packets across a network toward their destinations, through a process known as routing.

• connect wireless communication devices together to form a wireless Network.

Router

2 types of transmission medium2 types of transmission mediumA) Physical transmission media (guided medium)A) Physical transmission media (guided medium) - Twisted pair, Coaxial cable, Fiber optic - Twisted pair, Coaxial cable, Fiber optic

cable.cable. - eg: connect a PC to a printer - eg: connect a PC to a printer B) Wireless transmission media (unguided B) Wireless transmission media (unguided

medium)medium) - without using cables or cords.- without using cables or cords. - using radio frequency or infrared waves. - using radio frequency or infrared waves. - transmission divided into 3 categorized:- transmission divided into 3 categorized: i) Short range (Bluetooth or infrared)i) Short range (Bluetooth or infrared) ii) Medium range (WiFi / wirelass LAN)ii) Medium range (WiFi / wirelass LAN) iii) Long range (3G) iii) Long range (3G) - Listen to the radio- Listen to the radio - Talk over the telephone.- Talk over the telephone.

Physical Transmission Media Physical Transmission Media A) Twisted Pair Cable – 2 insulated copper wires A) Twisted Pair Cable – 2 insulated copper wires

that are twisted around each other. that are twisted around each other. B) Coaxial Cable – consisting of a conducting outer B) Coaxial Cable – consisting of a conducting outer

metal tube that encloses and is insulated from a metal tube that encloses and is insulated from a central conducting core, used primarily for the central conducting core, used primarily for the transmission of high- frequency signals.transmission of high- frequency signals.

C) Fibre Optic Cable – glass fibre used for laser C) Fibre Optic Cable – glass fibre used for laser transmission of video, audio and data.transmission of video, audio and data.

Wireless Transmission MediaWireless Transmission Media Mediums used are air, vacuum and water.Mediums used are air, vacuum and water. Wireless transmission: Wireless transmission:

i) Radio waves ( 1 and 300 GHz)i) Radio waves ( 1 and 300 GHz)

ii) Microwaves (2 types of antenna – ii) Microwaves (2 types of antenna –

parabolic antenna & horn antenna) parabolic antenna & horn antenna)

iii) Infrared (300 GHz – 400 THz)- cannot penetrate walls.iii) Infrared (300 GHz – 400 THz)- cannot penetrate walls.

Server Software Server Software Examples of network operating Examples of network operating

system:system:

i)i) Window NTWindow NT

ii)ii) Window 2000 server Window 2000 server

iii)iii) Window Server 2003 Window Server 2003

iv)iv) Red Hat Linux Red Hat Linux

Client SoftwareClient Software

Web browsers Web browsers

Wireless TechnologyWireless Technology

Global System For Mobile Global System For Mobile Communication (GSM)Communication (GSM)

General Packet Radio Service (GPRS)General Packet Radio Service (GPRS) Enhanced Data GSM Environment Enhanced Data GSM Environment

(EDGE)(EDGE) Universal Mobile telecommunications Universal Mobile telecommunications

System (UMTS)System (UMTS) Wireless Application Protocol (WAP)Wireless Application Protocol (WAP) i-MODE i-MODE

Types of wireless Types of wireless Fixed wireless Fixed wireless Mobile wireless Mobile wireless Portable wireless Portable wireless IR wireless IR wireless

Mobile computing Mobile computing Mobile computing is about the new strategies of Mobile computing is about the new strategies of

computing that utilise portable or mobile computing that utilise portable or mobile devices and wireless communication networks. devices and wireless communication networks. There are various types of mobile computing There are various types of mobile computing

devices such as notebook computer, tablet PC, devices such as notebook computer, tablet PC, handheld computer, PDA and smartphone. handheld computer, PDA and smartphone.

Common service for mobile Common service for mobile computing computing

Email capabilities Email capabilities Print stations Print stations Tracking and navigation system Tracking and navigation system Instant mobile massaging Instant mobile massaging Mobile security services Mobile security services