Computer Networks and Communication

COMPUTER NETWORKS AND COMMUNICATIONS (3.0)

Basic Concepts Of Computer Networks And Communications (3.1)Define computer networks (3.1.1.1) A computer network is a system of interconnected computers and peripheral devices.

(http://en.wikipedia.org/wiki/Computer_network)

Define communications (3.1.1.2) Communication is an activity of transferring information from a sender, across a distance, to a

receiver. (http://en.wikipedia.org/wiki/Communication)

Importance Of Computer Networks (3.1.2)State the importance of computer networks and communications. (3.1.2.1) E-Business – Sell and conduct online shopping through a network. Online education – Share knowledge, search for information and join and online discussion. E-banking – pay bills, browse account balance and transfer money to other parties without

going to the bank. Long distance communication – communication with people anywhere in the world can be

faster, and easier and save cost.

Types of Network (3.1.3)Define types of computer networks (3.1.3.1)

Local Area Network (LAN)A LAN cover a small region of space in a limited geographical area such as home, school, closely positioned group of buildings.

(http://en.wikipedia.org/wiki/Local_area_network)

Metropolitan Area Network (MAN)A MAN is a large computer network that usually spans a city or a large campus .

(http://en.wikipedia.org/wiki/Metropolitan_area_network)

Wide Area Network (WAN)A WAN is the largest network of all network types, for instance a country or even beyond the border.

( http://en.wikipedia.org/wiki/Wide_area_network )

Differentiate between the three types of computer networks (3.1.3.2)

CRITERIA LAN MAN WANNETWORK SIZE Covers a limited area

such as in a single building

Cover a greater area such as a city

Cover the largest geographical area such as the size of Malaysia

SPEED Very high speed network

A high speed network A slow speed network

COST Inexpensive hardware Expensive hardware Very expensive hardware

TRANSMISSION MEDIA TYPE

Twisted pair/ coaxial cables

Twisted pair/ fiber optic

Fiber optic/radio wave/ satellite

Network Architecture (3.1.4)Define two types of network architecture (3.1.4.1) Client/Server - One or more computers act as a server, and the other computers on the

network request service from the server. (Discovering computers 2006 A Gateway to Information, Shelly, Cashman,

Vermaat)

Peer-to-peer - Computer in peer- to -peer architecture has equal status. All the nodes acting as both servers and clients.

(ICT Based on SPM Syllabus, Venton)

Network Topology (3.1.5) In computer networking, topology refers to the layout of connected devices.

State three types of network topologies (3.1.5.1)Bus Ring Star

- Consists of all computer/node and other devices connected and communicate through a single central cable (backbone)

- If the backbone cable fails, the entire network unusable.

- Consists of all computers/nodes and other devices that are connected in a loop / same direction.

- If one node fail the entire network will fail.

- Consists of all computers/nodes connect to the central host / server/switch/hub/router directly.

- If one node fails, it doesn’t affect the entire network. But if the hub fails, the entire network also fails.

Differentiate between the three types of network topology (3.1.5.2)

Aspect Bus Topology Ring Topology Star TopologyStructure All computers/nodes

are connected to a single central cable (backbone)

All computers/nodes are connected in a loop

All computers/nodes are connected to central host directly

Connection between nodes

It has no connection between nodes but connect to backbone

It has connection between all the nodes

It has no connection between nodes

Ease of trouble shooting

Easy identification of cable faults

Easy to troubleshoot - Repair or remove the failing nodes

Difficult when one of the nodes fails but easy to troubleshoot when the host is fails.

Easy of adding or removing nodes

Easy to implement and extend. New devices can be added to the backbone or to the existing nodes

Difficult because moves, adds and changes of devices can affect the network

Easy to implement and extend. Only add the nodes or devices to the host

Node failure Failure of a node doesn’t affect the entire LAN as long as backbone is working

A failing node will affect the entire LAN

Failure of a node doesn’t affect the entire LAN as long as host is working

PROTOCOL (3.1.6)Define Transmission Control Protocol / Internet Protocol (TCP/IP) as a protocol to facilitate communication over computer network. (3.1.6.1)

Protocols provide the rules on how computers communicate. TCP/IP is a set of computer rules to enable computers to communicate over a network. TCP/IP provides end-to-end connectivity specifying how data should be formatted,

addressed, transmitted, routed and received at the destination.

Internet, Intranet, Extranet (3.1.7)

Describe the types of network communications technology (3.1.7.1)

INTERNET - The Internet is a global system of interconnected computer networks use the standard Internet Protocol Suite (TCP/IP) to serve billions of users worldwide

- It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic and optical networking technologies

INTRANET - An intranet is a private computer network

- Use Internet Protocol technologies to securely share any part of an organization's information within that organization

- Example of intranet application: telephone directories, job posting, event calendars

- Example employees can access the company information by using username and password

EXTRANET

EXTRANET - An extranet is a private computer network which allows partner/vendors/customer or suppliers to access part of its intranet.

- Also need username and password to access the company information

- Example such as an online banking application managed by one company on behalf of affiliated banks

DEVICES (3.2.1)Identify the devices needed in computer network communication (3.2.1.1)State the functions of the following devices (3.2.1.2)

TYPE OF DEVICES FUNCTIONS

Network Interface Card (NIC)

Network Interface Card (NIC) is also commonly referred to as a network adapter and is an expansion card that enables a computer to connect to a network using a given protocol.

Wireless Network Interface Card (WNIC)

Wireless Network Interface Card (WNIC) is a network card that provides wireless data transmission. This card uses an antenna to communicate through microwaves.

A modem is a device or program that

Modem (modulator-demodulator)

enables a computer to transmit data over, for example, telephone or cable lines. Use to convert digital signal to analog signal and vise versa.

Hub / Switch

A hub or switch is a device that provides a central point for cables in a network. Switches allow user to send information, such as email, and access shared resources, including printers

Router

A network device that forwards packets or data from one network to another according to the packet’s destination address.

Wireless Access Point

A Wireless Access Point is a central communications device that allows computers and devices to transfer data wirelessly to a wired network using Wi-Fi, Bluetooth or related standards.

Medium (3.2.2) Identify various types of cables such as Unshielded Twisted Pair (UTP), Shielded Twisted Pair (STP), coaxial and fiber optic cable (3.2.2.1)

Shielded Twisted-Pair Cable

Its Four pairs of colour-coded wires are each wrapped in metallic foil, and all four are then collectively wrapped in a layer of metallic braid or foil. Finally, this layer is wrapped with outer jacket.

Unshielded Twisted-Pair Cable

Consist of two wires or conductor twisted together, each with it own plastic insulation. Cancel out the electromagnetic interference that can cause crosstalk, the noise generated by adjacent pairs.

Coaxial Cable

The coaxial cable, often referred to as ‘coax’, consists of a single copper wire surrounded by at least three layers. They are an insulating material, a woven or braided metal and a plastic outer coating. This cable is often used as cable television (CATV) network wiring because it can be cabled over longer distances in comparison to the twisted-pair cable.

Fibre Optic Cable

The fibre optic cable is a networking medium that uses light for data transmission. The intensity of light is increased and decreased to represent binary one and zero. The binary system is a way of counting using just the two numbers 0 and 1.

Identify various types of wireless transmission media such as infrared, radio wave and satellite. (3.2.2.2)

Wireless Technology

In a wireless media however, signal transmission is unguided and the device communicates without using wires between nodes, usually by relying on radio frequencies instead.

Infrared

Infrared is a wireless transmission medium that sends signals using infrared light waves. Infrared is used in devices such as the mouse, wireless keyboard and printers. Some manufacturers provide a special port called the IrDA port that allows a wireless keyboard to communicate with a PC. Infrared signals have frequencies between 300 GHz to 400 THz.

Radio wave

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. When an antenna transmits radio waves, they are propagated in all directions. This means that the sending and receiving antennas do not have to

Radio wave

Infrared

be aligned. Our AM and FM radio stations, cordless phones and televisions are examples of multicasting.

SatelliteSatellite is an object which has been placed into orbit by human endeavor. A communication satellite is a space station that receives microwave signals from an earth-based station, amplifies (strengthen) the signals, and broadcasts the signals back over a wide area to any number of earth-based stations.

Server Software (3.3.1)

Define Network Operating System (3.3.1.1)

A Network Operating System or known as NOS, has additional functionality that allows it to connect computers and peripherals to a network.

They provide the capabilities required for network operation. Network operating systems are also designed for client computers and provide functions so the distinction between network operating systems and stand alone operating systems is not always obvious.

Name various Network Operating System Software (3.3.1.2) Windows NT

Satellite

Windows 2000 Server Windows Server 2003 Red Hat Linux

Client Software (3.3.2)State the functions of various client software. (3.3.2.1)

Web Browser

A web browser is a software application that enables a user to display and interact with HTML documents hosted by web servers or held in a file system. Text and images on a web page can contain hyperlinks to other web pages at the same or to different websites. Web browsers allow a user to quickly and easily access information provided on many web pages at many websites by surfing these links. Web browsers available for personal computers include Microsoft Internet Explorer, Safari, Netscape and Opera.

Email Client

An email client is a computer program that is used to read and send email. Outlook Express and Thunderbird is a Microsoft application that is included as part of the Microsoft Windows OS.

Network Utilities

Network Utilities are small computer programs that are used to test various aspects of a network. Among the utilities provided are ping and Trace Route.

Note: Ping - Ping is a computer network administration utility used to test the reachability of a host on an Internet Protocol (IP) network.

Trace Route - traceroute is a computer network tool used to show the route taken by packets across an IP network.

Network File Manager

A network file manager is a software tool that provides a user interface to work with computer network files. Examples are Network Neighborhood and My Network Places.

Setting Network Facilities (3.4)

Installation of Network Interface Card (NIC) (3.4.1)

Network Interface Card (NIC)

Insert Network Interface Card (NIC) (3.4.1.1)

Insert the Network Interface Card into the slot and firmly pressing the card down.

Secure the card in place with the screw from the blanking plate.

Replace the casing or side panel of your PC.

Finally, boot the PC and install the driver.

Install Driver for the NIC (3.4.1.2)Example : Installing The NIC Driver For Windows XP

Windows will indicate that it has found a new hardware after the NIC has been inserted into its slot. The “Found New Hardware Wizard” will then appear. Click “Next” to continue.

Step 1: Select “Search for the best driver for my device (recommended)” and click “Next” to continue.

Step 2: Select “CD-ROM Drives” and click “Next” to continue. Windows will now search for a suitable driver for your device.

Step 3: Windows will locate the correct driver for your device and indicate that it is now ready to install the driver. Click “Next” to continue.

The NIC driver is now properly installed.Restart the computer to complete the installation.

Setting Network Facilities (3.4)Cable Crimping and Testing (3.4.2)

STRAIGHT CABLE

ITEMS FOR MAKING STRAIGHT CABLE

Cat5 CableCAT 5 cable has four twisted pairs of wire for a total of eight individually insulated wires.Each pair is colour coded with one wire having a solid colour: Blue Orange Green BrownTwisted around a second wire with a white background and a stripe of the same colour.

RJ-45 is the standard connector utilized on 4-pair (8-wire) UTP Unshielded Twisted Pair) cable.

Crimp tool - to crimp RJ-45 connectors. Cutters - to cut the cable off at the reel and to fine tune the cable ends during assembly. Cable Tester - A cable tester is an electronic device used to verify the electrical

connections in a cable or other wired assembly.

CABLE CRIMPING PROCESS

The total length of wire segments between a PC and a hub or PC to PC cannot exceed 100 Meters.

Strip one end of the cable with the stripper or a cutter.

If you are using the stripper, place the cable in the groove on the blade (left) side of the stripper and align the end of the cable with the right side of the stripper.

Spread and arrange the pairs roughly:White/Green, Blue White/Blue, Green White/Brown, Brown White/Orange, Orange

Trim the ends of the wires so they are even with one another.

It is very important that the unstripped or untwisted end be slightly less than half-inch long.

If it is longer than half-inch it will be out of its specifications and will cause crosstalk.

If it is slightly less than half-inch long, it will not be properly clinched when RJ-45 plug is crimped on.

There should be little or no space between the wires.

Hold the RJ-45 plug with the clip facing down or away from you. Push the wire firmly into the plug.

Inspect it carefully. Looking through the bottom of the plug, the wire on the far left side will have a white background

The wires should all end evenly at the front of the plug.

Hold the wire near the RJ-45 plug with the clip down and firmly push it into the front-left of the crimper.

Hold the wire in place and squeeze the crimper handles quite firmly. Crimp it once. Finally test the crimping result.

Test the crimp strength. If it is done properly, an average person will not be able to pull the plug off the cable with

his or her bare hands.CROSSED CABLE

This cable can be used to directly connect two computers to each other without the use of a hub or switch.

Configuration and Testing of Network (3.4.3)

Configure the workstation to join a Local Area Network (3.4.3.1)

The first step is to open the Control Panel window.

Select Network and Internet Connections.

Click on the Network Connections icon.

Inside the Network Connections window, right click on Local Area Connection icon. Then click on Properties in the drop down menu.

In the next dialogue box, click on Internet Protocol (TCP/IP) icon.

Then click on the properties button. After the properties button is clicked, the Internet Protocol (TCP/IP) Properties window will appear. You will see details like IP address, Subnet mask and Default gateway. Subnet mask specifies the size of the network. Here, we usually use 255.255.255.0 for small networks. Gateways are used to connect to other networks and the Internet.

Test the network connection. (3.4.3.2)

1. From the Start menu select Programs and DOS Prompt to open up a DOS window.

Type ping followed by your IP address.

2. If you successfully sent and received packets, all is well with the TCP/IP connection.

3. If ping displays error messages such as:

request timed out unknown host could not send, receive packets over the network

Share Data (3.4.4)

Create a shared folder.(3.4.4.1)

Click Start then "My Computer"

Go to the directory above the one you wish to share. In this example I will share the folder "folder" on G:

Right click the folder and click "Sharing and Security"

Click "Share this folder" than if you would like, change the name of the desired share. After you do that, click the "Permissions" button

Now you can change who will have access to what on this shared resource, but for the sake of this tutorial, we will give "Everyone" "Full Control". After you select "Allow" for "Full Control", Click "OK" and "OK" on the Share window

Go back to the folder above the shared one in Explorer and you will see a hand under the folder icon which shows that the folder is now shared

And that's it for the sharing section.

Current and Future Developments (3.5)

Mobile Computing DefinitionMobile computing is a generic term describing one's ability to use technology while moving, as opposed to portable computers, which are only practical for use while deployed in a stationary configuration.

( en.wikipedia.org/wiki/Mobile_computing )

Specification, Services, and Frequencies of Mobile Computing(http://www.htc.com/www/product/touch3g/specification.html)

HTC TOUCH 3G

SPECIFICATIONS

Network HSDPA/WCDMA: Europe/Asia: 900/2100 MHzUp to 384 kbps up-link and 7.2 Mbps down-link speedsQuad-band GSM/GPRS/EDGE: 850/900/1800/1900 MHz(Band frequency and data speed are operator dependent.)

Processor Qualcomm® MSM7225™, 528 MHz

Operating System Windows Mobile® 6.1 Professional

Memory ROM: 256 MBRAM: 192 MB

Dimensions (LxWxT)

102 mm X 53.6 mm X 14.5 mm(4.016 inches X 2.110 inches X 0.571 inches)

Weight 96 grams (3.386 ounces) with battery

Display 2.8-inch TFT-LCD flat touch-sensitive screen with QVGA resolution

Camera 3.2 megapixel color camera with fixed focus

Audio Built-in microphone and speakerRing tone formats: AAC, AAC+, eAAC+, AMR-NB, AMR-WB, QCP, MP3, WMA, WAV40 polyphonic and standard MIDI format 0 and 1 (SMF)/SP MIDI

Battery Rechargeable Lithium-ion batteryCapacity: 1100 mAh

Talk time:

Up to 360 minutes for WCDMAUp to 400 minutes for GSMStandby time: Up to 450 hours for WCDMAUp to 365 hours for GSM(The above are subject to network and phone usage.)

Expansion Slot microSD™ memory card (SD 2.0 compatible)

AC Adapter Voltage range/frequency: 100 ~ 240V AC, 50/60 HzDC output: 5V and 1A

SERVICES

Device Control * HTC TouchFLO™* 4-Way navigation control with Enter button

GPS Internal GPS antenna

Connectivity Bluetooth® 2.0 with Enhanced Data Rate and A2DP for stereo wireless

headsetsWi-Fi®: IEEE 802.11 b/gHTC ExtUSB™ (11-pin mini-USB 2.0 and audio jack in one)

FREQUENCIES

Processor Qualcomm® MSM7225™, 528 MHz

Network HSDPA/WCDMA: Europe/Asia: 900/2100 MHzUp to 384 kbps up-link and 7.2 Mbps down-link speedsQuad-band GSM/GPRS/EDGE: 850/900/1800/1900 MHz(Band frequency and data speed are operator dependent.)

Internet Technology and Services

VoIPVoice over Internet Protocol (VoIP) is a general term for a family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switched networks.

(http://en.wikipedia.org/wiki/Voice_over_Internet_Protocol)

BlogA blog (a contraction of the term "web log") is a type of website , usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video.

(http://en.wikipedia.org/wiki/Blog)

Types of Network

PAN A personal area network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one's person.

( http://en.wikipedia.org/wiki/Personal_area_network )

VPNA virtual private network (VPN) is a network that uses a public telecommunication infrastructure, such as the Internet, to provide remote offices or individual users with secure access to their organization's network.

(http://en.wikipedia.org/wiki/Virtual_Private_network)

WLAN

A wireless LAN (WLAN) is a wireless local area network that links two or more computers or devices using spread-spectrum or OFDM modulation technology based to enable communication between devices in a limited area.

(http://en.wikipedia.org/wiki/Wireless_LAN)

WIMAXWiMAX, meaning Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides wireless transmission of data using a variety of transmission modes, from point-to-multipoint links to portable and fully mobile Internet access.

(http://en.wikipedia.org/wiki/WiMAX)

References: http://en.wikipedia.org/wiki/Bus_networkhttp://en.wikipedia.org/wiki/Ring_networkhttp://en.wikipedia.org/wiki/Star_networkhttp://en.wikipedia.org/wiki/Internethttp://www.businessdictionary.com/definition/intranet.htmlhttp://www.mariosalexandrou.com/definition/extranet.asphttp://compnetworking.about.com/od/networkdesign/a/topologies.htmhttp://www.google.com.my/search?hl=en&biw=1024&bih=578&defl=en&q=define:internet&sa=X&ei=p6m7TPCXE4zcvQPs583sDQ&ved=0CB4QkAEhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Extranethttp://www.visualwin.com/VSS/Part1.htmlhttp://www.webopedia.com/TERM/I/IP_address.html