Explanation On How The Topologies Operate Computer Science Essay

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A single cable used in a shared communication medium that devices attached with an interface connector. A device wants to communicate with another device on the network it sends a message into the medium that all the other devices see, but only the intended recipients accept the message and processing.

Ring topology every device has two neighbors for communication purposes, all messages travel through a ring in the same direction, incase failure of any cable or device the total loop will not in operation.

Star topology most of the in-house networks use the same, a star network features a central connection point called hub that may be a hub, switch or router. All the devices connected to the hub with Unshielded Twisted Pair Ethernet.

Tree topology integrated multiple star topologies together onto a bus, hub is directly connected to the tree bus, and each hub functions as the root of a tree of devices.

Mesh topology involves the concept of routes, messages sent on a mesh network can take any of several possible paths from source to destination.

Explain advantage and disadvantage of each medium.

UTP CABLE relies on the twisted wire pairs to create a cancellation effect which will limit signal degradation caused by electromagnetic radio interference. The twists also reduce the crosstalk between the pairs in the cable.

UTP Disadvantages: it is more prone to interference than other types of cables, and the distance that a signal can travel is shorter for UTP than coaxial and fiber-optic cables.

Coaxial cable can run for longer distances between network nodes without needing a signal boost from a repeater. They are less expensive than fiber-optic cables.

Disadvantages of coaxial cable: it is too rigid and this can hinder installation. Coaxial cable is more expensive to install than twisted-pair cable. Improper grounding of the outer copper or metallic braid can result in electrical noise which will interfere with signal transmission on the network.

Fiber optic cables are practically immune to all types of interference and noise, and offer improved security.

Disadvantages of fiber: fiber is very expensive to purchase and it requires specialized equipment and techniques to install.

Wireless: Wireless medium include microwave, infrared, radio frequencies and satellite. Wireless media is faster to deploy and less costly than installing cables. Wireless is also useful where the environmental makes it impossible to use cable.

Disadvantages associated with wireless; wireless solutions provide lower data rates than their wired counterparts. Wireless signals are greatly affected by external environment. One of the biggest disadvantage of using wireless signals is its security, and the signals have to be encrypted in order to ensure privacy.

Provide a recommendation for which topology and medium to use including reasons for this recommendation.

Star topology is recommended for this application, a star network features a central connection point called hub that may be a hub, switch or router. All the devices connected to the hub with Unshielded Twisted Pair (UTP) Ethernet.

A star network generally requires more cable, failure in any star network cable will stop one computer's network access and not the entire LAN. If the hub fails the entire network fails.

Task - 2

Describe the Internet services that may be required.

World Wide Web (Internet): Internet connection is required for mail communication to the outside world for employees and common public to send feedback or report issues.

Telnet: Required for support personnel to remotely connect for troubleshooting

FTP - File Transfer Protocol for uploading and downloading files for support

Newsgroups: Subscriptions to newsgroups or creation of newsgroups will inform common public about departments.

Fire department site : Website for the department

Explain the connection speeds that are suitable for these requirements.

ISDN (Integrated Services Digital Network) is a more flexible digital alternative to the standard analogue telephone line for Fire Department services.

ISDN is a preferred option. ISDN connection or the Integrated Services Digital Network is a facility where could speak, see video and exchange data within the digital phone line with speeds ranging between 64Kbps to 128Kbps.

An ISDN line can be a useful backup service for businesses; if the primary link fails, the ISDN line takes over and your business communications are not interrupted.

Find examples of Internet Service Providers (ISPs) that can meet these requirements in your country.

In UAE there are only Two ISPs providers they are DU and Etisalat.

Make a recommendation to use one ISP based upon the services offered and price charged.

I recommend a 2MB dedicated line for the department.

The Internet Service Provider is Etisalat their network is widely covered, and they provide free Router.

Task - 3

Investigate the methods the Fire Department could implement for two-ways voice communications. As a minimum include the following information:

How each method works

Gsm, it is a Full duplex communication operates with 2G, Frequency range at

1800 Mhz, uplink 1715 to 1785 Mhz, downlink 1805 to 1880 Mhz,

Channel spacing 200 Khz, Band width 144 kbps, Emergency no. (Fire, Police, Ambulance, Electricity, Water, gas) calls are free.

Private Mobile Radio Service (Two-way radio, RF Radio), This is Half duplex. Working frequency range between 9 khz to 3000 Ghz, the frequency allocation will be provided by Telecommunication Regulatory Authority,

Satellite telephone, (Thuriya) It is a full duplex communication device (service), directly communicates through satellite, it operates through C band, Frequency range is 4 to 8 Ghz, It has got satellite microwave link antenna, available services are voice, sms and low band internet.

Details of the legal requirements for operation the system in your country (e.g.) allocation of frequencies, licensing requirements, etc).

Private Mobile Radio Service,

In United Arab Emirates, the license can be obtained from the (TRA) TELECOMMUNICATION REGULATORY AUTHORITY, Frequency spectrum Authorization for private mobile ratio services.

Since Fire Department is the part of Public Service Department, allocation of Frequency will not be a problem,

Coverage area to be specified (Within the site, or the city limit) Fire Department requires a whole town coverage. The frequency range will be provided by TRA, and equipment must be bought accordingly.

Cost of setting up and operating the system, including licensing costs, etc.

Motorola Two-Way radio is widely used radio system, This ratio also support an interface that allows Third party software to develop and create application that run on as a separate control.

The base station of Motorola Model GM 340 is $ 800. Each 800*2 = $1600

The Vehicle base station Model GM 340 is $ 800. Each 800*6 = $4800

The hand set Ratio Model GP 328 is $ 250. Each 250*8 = $2000

The base station power supply & antenna is $ 350. Each 350*2 = $700

The installation cost will be $ 300. $300

Since Fire department is public service one

The radio licensing will be free of charge.

The total cost of setting up the radio system will be $9400

Limitations of each method:


Complexity signal strength to be covered by the transmission tower, it is a battery operated unit battery is always charged, service provider to ensure the service is available all the time.


Complexity it is a battery operated unit the battery to be charged, base station power supply should connected through (UPS) uninterruptable power supply, while talking talk push button to be pressed for mike operation, channel selector button to be selected in allocated channel, RF antenna to be provided near the base station, if it is mobile unit then the vehicle should have RF antenna.


Complexity should track the position of satellite, climate disturbance like cloudy and rain.

Provide a recommendation for how voice communications should be set up and run including reasons for this recommendation.

Radio communication is recommended because it is cheap, easy to setup and operate and provides the services required by the fire department. Other communication methods rely on the service providers.

Task 4

The main equipment that would be installed.

Panasonic NCP Phone Systems

KX-NCP 500/1000The NCP platforms combine advanced digital and IP telephony together with integral user productivity applications, providing extensive business communications functionality.

The features available with each system.

KX-NCP 500/1000 Features

Enhance User Productivity

• VoIP

• Application Integration

• Support for cordless phones

• Built-in Application Server - providing desktop solutions

• Choice of IP, digital, analogue or wireless DECT terminals

• Voicemail

Enhance Remote User Productivity

• SIP support

• Remote dialing supported

Strata CIX100 IP Telephone System Features and Capabilities

Toshiba's IP business communication systems provide optimum solutions for any sized business whether you need a basic telephone system or one with advanced capabilities.

Advanced Applications

Toshiba's Media Application Server (MAS) connects to Strata CIX IP Systems via Ethernet and hosts a variety of value-added applications integrated within one platform.

Applications include:

• Auto Attendant and Voice Mail

• Unified Messaging and Fax Integration

• Automated Speech Recognition (ASR)

• Text-to-Speech (TTS)

• Interactive Voice Response (IVR)

• Automatic Call Distribution (ACD) and ACD Reporting

• Call Manager unified communications

• Video Conferencing, file sharing, and collaboration solutions

The cost equipment and installation.

(KX-NCP 1000x IP PBX 4 x SIP Trunks, 12users)

The PBX with 12 extension with extendable ports cost $ 2100

The installation and commissioning cost $ 400

The total cost of installation will be $ 2500.

The cost of operating system.

The PBX equipment and installation cost will be $ 2500

The cable from the distribution board to the building will be provided by the service provider, from the building termination box to pbx and pbx to extensions and other equipments to be laid it will be cost around $ 1000.

Service and connection charges will be $ 400.

The total cost of operating system will be $ 3900.

Provide a recommendation for which system to purchase including reasons for this recommendation.

Panasonic is recommended because it is cheap, reliable and it has got more feature than other systems for the fire department single site operation.

Task 5

It is crucial that the Fire Department stays online at all times and there should always be a backup plan in the case that anything goes wrong. The list below details some of the measures that can be taken:


The Fire Department can use satellite or GSM networks to transfer data to mobile units. If they don't have their own GSM network, they can use the carrier network to ensure on-going communication.

Natural disasters

Natural disasters cannot be avoided but the risk can be reduced. Therefore, all data held within the servers must be backed up and stored offsite. This will reduce data loss and recovery will be easy.


Every server, base station and telephone exchange should be connected to an Uninterrupted Power Supply, or a generator or a battery connected to a solar panel.

All data centers should have methods to counteract fires and terrorists.

Task 6

Star Topology is recommended for for this application, a star network features a central connection point called hub that may be a hub, switch or router. Failure in any star net work cable will stop one computer not the entire network.

Requirement of internet services World Wide Web (Internet): Internet connection is required for mail communication to the outside world for employees and common public to send feedback or report issues. Telnet, FTP, Newsgroup, Website.

How the each method of communication work is explained (Task 3), required services are, Gsm, Private Mobile Radio and Satellite telephone.

Single site best telephone system recommended. Panasonic KX-NCP 1000X.

All the necessary system backup and natural disaster recovery explained in Task 5.

All the above are the findings and recommendation for the fire department.