Operation Of Star Topology Computer Science Essay

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According to the review at whole reports, I have to know basic network topologies such as bus topology and star topology. And I know the advantages and disadvantages of these topologies and which topology and media is suitable with the in-house network (LAN) for the Police Department. Then, I recommend about topology, why I choose those topology. I don't know all of about topology and others but I try to report and to know as possible.

I investigate the internet connection requirements for the police department. And find out why police department require the internet connection services. The suitable of the internet connections services speeds are known in our country. Why high speed internet connection is required for what kind of facts.

And I had to implement for two-way voice communications full duplex and half duplex. I also need to find legal requirement, allocation of frequencies, licensing requirements for full duplex and half duplex in our country. And then, I need to find out the cost of setting up and operating the system, including licensing costs and equipment costs. When I know them, I have to find limitation for full duplex and half duplex.

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After, I need to know for single-site organization like the police department in our country. I think, Public Branch Exchange (PBX) and Key Telephone System (KTS) are suitable for single- site organizations. They are suitable in their own purpose. After that, I need to find out equipment cost, installation cost and operating the system.

Investigate the possible network topologies and media that could be used to create the in-house network (LAN) for the Police Department.

Firstly I investigate the task1 assignment, consists of topology and medium. I created the topologies and medium in the search internet. But I search the internet very different. All of the end of task 1 assignment, I am not satisfaction. The network topologies submit to the configuration of cables, computers, and other nonessential. Network topology had different logical topology which is defined to pass data information between each workstation or server and client. There are four basic network topologies such as star, ring. I explain the ring topology and Star topology below.

Operation of star topology

Star topology is a connected to a central point by a separate cable. Many businesses and home networks use the star topology. The design of a star topology resembles an old wagon with the wooden spokes extending from the center point. It is can add new stations just by running a single new cable. All user nodes are connected via a dedicated link to the central server node. If a node other than the server fail all other route are still available. If the server fails the whole network fails.

Operation of ring topology

In the ring topology, each computer is connected directly to two other computers in the network. Data moves down a one-way path from one computer to other. The bad news is that, as with bus topology, any beak, such as adding or removing a computer, disrupts the entire network. Also, because you have to break the ring in order to add another station, it is very difficult to reconfigure without down the station, it is very difficult to reconfigure without bringing down the whole network. For this reason, the physical ring topology is seldom used.

Fiber Optic Cable

Fiber optic cabling consists of a center glass core surrounded by several layers of protective materials. It transmits light rather than electronic signals eliminating the problem of electrical interference. This makes it ideal for certain environments that contain a large amount of electrical interference.

Advantages

It also has the capability to carry information at vastly greater speeds.

Cable of covering large areas

Most popularly used intruded upon.

Disadvantages

More expensive

Unshielded Twisted Pair (UTP) Cable

UTP cable is the wires in this cable type are twisted. When electromagnetic signal are conducted on copper wire that are in close proximity, some electromagnetic interference occur.

Advantages

Easy Troubleshooting

Easy Move and Changes

Disadvantages

Distance

Sensitive to Noise

Coaxial Cable

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Coaxial Cable contains a centre conductor, made of copper, surrounded by a plastic jacket, with a braided shield over the jacket.

Advantages

Resists EMI better than twisted pair

Allows for longer distances

Disadvantages

Cable is heavy, bulky and expensive

Difficult install

Businesses typically use the Star topology because easy to manage and easy to locate problems (cable/workstations). Moreover it can easier to expend than a bus and ring topology.

Fiber optic cable makes it ideal for certain environments that contain a large amount of electrical interference. It has also made it the standard for connecting networks between. This has the ability to transmit signals over much longer distances than coaxial and twisted pair.

For voice communication over the Internet. (e. g. Voice Over IP)

For use to E-mail (Electronic Mail), sending messages from one Internet user to another using Internet as delivery mechanism.

The headquarters will house all the communications and computer system for the Police Department.

To send top secrets data.

To connect Townsville Police Department and four districts headquarters building.

To used investigate serious crimes such as murder.

The connection speeds that are suitable for these requirements are 512 kbps. It is high bandwidth, high speed internet access and secure. So, it won't be slowed down by heavy traffic while dialing into an Internet Service Provider (ISP).

Broadband ADSL Services

Activation fee (FEC) 840, monthly fee (FEC), free e-mail accounts 25, 2 VoIP services, speed (MIR) 512, data limit (MB) 10,000.

IPstar Satellite Broadband

Activation fee (FEC) 1,250, monthly fee (Kyat) 280,000, free e-mail accounts 25, 2 VoIP services, speed (MIR) 384, data limit (MB) 10,000.

Broadband wireless

Activation fee (FEC) 840, monthly fee (FEC) 130, free e-mail accounts 25, 2 VoIP services, speed (MIR) 512, data limit (MB) 10,000.

Broadband ADSL Service is suitable for these requirements.

ADSL is a technology that allows telecommunication service providers to use today's existing wiring to the home for high-speed digital communications.

Free e-mail accounts are 25, 2 VoIP services, (MIR) 512 speed.

Activation fee is FEC 840, monthly fee is FEC 130, data limit (MB) 10,000.

Cordless Telephone

The most cordless telephone frequencies are 900 MHz (902-928 MHz). A cordless telephone offers full duplex.

- Public Trunked Mobile Radio (PTMR)

Half duplex operation requiring strict operation procedures. The PTMR frequencies are eight frequencies used are 697, 770, 852, 941 Hz which are termed the "low tones" and 1209, 1336, 1477, and 1633 Hz which are "high tones".

- Global System for Mobile (GSM)

Full duplex operation requiring strict operation procedures.

The most frequencies are 1800MHz.

- Cordless Telephone

The most cordless telephone frequencies are 900 MHz (902-928 MHz)

Requires a license from the appropriate government department

Public Trunked Mobile Radio (PTMR)

The PTMR eight frequencies used are 697, 770, 852, 941 Hz which are termed the "low tones" and 1209, 1336, 1477, and 1633 Hz which are "high tones".

Requires a license from the appropriate government department

- Global System for Mobile (GSM)

GSM allocation of frequencies is 1800MHz

Permits roaming with other countries networks

To have the call charges passed back to their home cellular network service provider.

- Cordless Telephone

Licensing costs are 100,000 kyat at one month.

Equipment costs one base and two handset are 110,000 kyat.

Public Trunked Mobile Radio (PTMR)

Licensing costs are 80,000 kyat at one year.

Equipment costs one base station and one handset is 230,000 kyat.

Global System for Mobile

Licenses costs are 1,650,000 kyat.

Equipment costs are 350,000 kyat.

- Cordless Telephone

900 MHz cordless phones are still sold today and have a huge install, feature include even shorter antenna, up to 30 auto selecting channels, and higher resistance to interference.

Public Trunked Mobile Radio (PTMR)

Coverage limitations (25 km radius)

The antenna may be mounted on a high tower; coverage may extend up to distances of 50 kilometers apart.

Global System for Mobile

Data speed up to 9.6 Kbit/s without the need for modems, by a data port on the handset.

Public Trunked Mobile Radio (PTMR)

PTMR is suitable for these requirements. This is a radio-based network service are offered in other. The business and government requires communications between a fixed set of user (a closed user group).Network operator allocates information channels and polices network. Moreover, PTMR is designed of voice communications but it can also support data.

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PBX

PBX is acronym for Private Brach Exchange which is very powerful phone system. PBX is an automatic call distribution system. PBX means any kind of switchboard system that allows users to reach each other by phone not using the general telephone system. PBX system is run by hand by telephone operators.

PBX system uses digital technology to control a central processing unit (CPU) to connect any internal extension to any external line and to allow internal extensions to connect to each other. PBXs are more economic for larger installations. PBX system selects external line.

PBX's basic features are-

Dial other extensions

Dial external lines

To receive external calls

To make an enquiry call to another extension

To transfer a call to another extension

PBX provides a signal when a call is being received. It sends a signal to the exchange when the user wants to originate a call. It also permits the user to advise the exchange to what number the call should be connected. PBX advises the exchange when a call is finished. It converts voice signals to varying electrical signals to allow their movement via an electrical circuit. It also converts varying electrical signals back to voice signals and present these to the user in an audible form and receive voice signals in preparation for conversion.

If the business is small then a single telephone line may suffice. It is more nowadays for any business to manage without at least two lines, one for telephone calls and the other for use with a facsimile machine, or personal computer.

Equipments for PBX

RJ11 Jack

Cables

Modem Surge Protector

Telephone

Central Processor

KTS (Key Telephone System)

Key Telephone System is smaller than PBX system and it is cheaper than PBX. KTS is equipped with several buttons that allow a caller to directly select outgoing lines or incoming calls. KTS also uses intercoms and conference facilities. In KTS, the user does not need to dial 9 to access the phone line.

KTS is a multi-line phone system. It is commonly used in small organization.

Equipments for KTS

RJ11 Jack

Cable

Modem Surge Protector

Telephone

Features of PBX system are-

PBX account code

PBX alternate number ring

PBX attendant

PBX automatic hold

PBX automated directory

PBX automatic call delivery

PBX Call Center Technology

PBX call forwarding

PBX call monitoring

Passive call recording

PBX call return

PBX account code

Account code is used for tracking bill for the user by entering account code during the conversation.

PBX alternate number ring

A function used for assigning more than one extension number so that if one of the numbers is dialed by a particular line. This rings when one of the extension number is dialed by one tone and another tone rings when other extension number is dialed.

PBX attendant

It is a kind of extension to which calls can be transferred to if the person deals 0. The attendant number can be changed by the operator from 0.

PBX automatic hold

During a call, the user can select a new outgoing line according to this function by the system places the original call on hold and the user receive dial tone.

PBX automated directory

A program with name of people from the organization and their extension number is called automated directory. A caller from outside the organization can check the person name spelling and their extension numbers from the organization by using this feature.

Automated call delivery

It is known as ACD system. It is used to route calls in a call center to the appropriate place. It places calls into a queue where they are typically handled in the order received. It can handle routing of inbound or outbound calls.

PBX call center technology

This technology supports automated phone systems capable of answering incoming phone calls and performing outbound autodialing. A call center is a department in the organization corporate this technology.

PBX call forwarding

It is a function to route calls to other places. Call forwarding takes place when call forward on busy, transferred when the original extension is engaged.

PBX call monitoring

A supervisor tapping into a phone transaction between an agent and a caller is called call monitoring. Some examples are-

Voice only monitoring and

Voice and data monitoring

Features of Key Telephone System

Automatic Call Back

Automatic Call Redial

Call Trace

Call hold

Call barring

Call diversion- calls transfer to another extension

Conference Call

Dial other extensions

Dial external telephone lines

Night Service - Handle out-of-hours calls

Receive external calls

Short code dialing

User select the external outgoing line

PBX

Central equipment and installation cost

Item

Quantity

Unit Price(USD)

Total Price(USD)

Central Processor-Cisco M-xs9164

1

1700.00

1700.00

Operation control Device

1

450.00

450.00

Operation Software Cost

1

135.90

135.90

Gateway-

Cisco R-tc261

1

500.50

500.50

Installation Cost

1

590.00

590.00

Total cost

3376.40

Client

Item

Quantity

Unit Price(USD)

Total Price(USD)

Cisco SPA942 Phone

1

95.00

95.00

RJ-11 Standard Modem/Phone Cable (50 Feet)

3

7.88

23.64

RJ-11Connector

2

4.00

8.00

Installation Cost

1

80.00

80.00

Total cost

206.64

KTS

Central equipment and installation cost

Item

Quantity

Unit Price(USD)

Total Price(USD)

Central Processor-Cisco M-xs9164

1

1700.00

1700.00

Cisco SPX-860 Phone

1

444.00

444.00

UM IP Gateway-

Cisco R-tc261

1

546.00

546.00

Installation Cost

1

322.00

322.00

Total cost

3012.00

Client

Item

Quantity

Unit Price(USD)

Total Price(USD)

Cisco SPA942 Phone

1

95.00

95.00

RJ-11 Standard Modem/Phone Cable (50 Feet)

3

7.88

23.64

RJ-11Connector

2

4.00

8.00

Installation Cost

1

80.00

80.00

Total cost

206.64

The cost for operating the system is as the follow

Item

Cost

Initial state charge

$1400.00

Licensing charge

$1100.00

Registering user

$700.00

Charges for line man

$280.00

Charges for incoming call (average 200 minutes per month)

$80.00

Charges for outgoing call (average 200 minutes per month)

$130.00

Charges for yearly fee

$260.00

Total Cost

$7900.00

The total cost for setting up the system $7900.00. Incoming call and outgoing call are calculated with average.

PBX phone systems are suitable for this business. While the overall costs of a PABX system are higher than other systems, but the functionalities of PABX phone systems are higher than the other systems as well as more economic to install a PABX with standard telephone instruments. They are very lightweight phone systems designed for organizations with fewer than 10 employees that also have very basic phone requirements. They are portable and can be moved easily if you relocate. It is easy to set up and run. Adding extensions and lines to a PABX telephone system is very simple and straightforward, making upgrades relatively simple and cost-efficient. PBX system is easy to extendable new phone line in the organization. PBX system is programmable and can support integration requirements. The advantages of PABX telephone systems are Abbreviated or Short Code Calling, Enquiry Call, Transfer Call to Enquiry Extension, External Call with Someone on Hold, Saved Number Dialed, Extension Night Service, Automatic Call Back, Conference Call, Automatic Answer and Last Number Re-Dial. At these good facts and advantages, we should use the PBX telephone system.

Assumption and choice

I advise Star Topology and Radio wave. The reason for advice is all user nodes are connected via a dedicated link to the central server node. If a node other than the server fails all other routes are still available. If the server fails the whole network fails Data on a star network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, or concentrator manages and controls all functions of the network. It also acts as a repeater for the data flow. This configuration is common with twisted pair cable; however, it can also be used with coaxial cable or fiber optic cable. A linear bus network may be the least expensive way to install a network. The linear bus network uses shorter lengths of cable. With a star topology, expanding a network is easily done by adding another concentrator. The most common cable is unshielded twisted pair, which is most often used with star topologies. So, I choose star topology.

And Radio wave is more flexible rather than cable for use police department. The police system does not need WAN network. We determined to prefer 8 Mbps internet connection speed from Myanmar Info Tech (MPT) Internet Service Provider (ISP). 8 Mbps connection speed is suitable for the police system requirement. Police can make their job as quick as with that speed. The other cause is Myanmar Info Tech (MPT) Internet Service Provider also give appropriate fees charge for not only government organization but also for the public and other organization.

We decide to choice Public Trunked Mobile Radio (PTMR), system for the police division. The PTMR setting cost is very cheap rather than GSM. All police can hear the other police talking clearly and can know the instructions. Using PTMR does not need special facts for use PTMR and easy to change and flexible for use. So, I think PTMR is suitable for police station.

I determined to decide and install private branch exchange (PBX) system between private branch exchange (PBX) and Key Telephone System (KTS) system. The private branch exchange (PBX) system can called other with lack of charge. The system does not require any physical hub and all police can accept call from outside of the organization. Therefore police can communicate the outside of the organization. Private branch exchange (PBX) system is easy to extendable new phone line in the organization. Physical hub does not require a large amount of space and low profile. Private branch exchange (PBX) system allows all polices to call outside of the organization. Therefore every police can communicate the outside of the organization. Private branch exchange (PBX) system allows all police to transfer phone line to other police phone line if dialer is from the outside of the organization or within the organization. I determine to install private branch exchange (PBX) system between private branch exchange (PBX) and Key Telephone System (KTS) system. The private branch exchange (PBX) system can called other with lack of charge. The system does not require any physical hub /switch and all police can accept call from outside of the organization. Therefore police can communicate the outside of the organization. Private branch exchange (PBX) system is easy to extendable new phone line coverage by using repeaters in the organization. Physical hub does not need a much space and low profile. Private branch exchange (PBX) system allows all polices to call outside of the organization. Therefore every police can communicate the outside of the organization. Private branch exchange (PBX) system allows all police to transfer phone line to other police phone line if dialer is from the outside of the organization or within the organization.

Review of work, weakness and improvement

I have to find network topologies and cable for network media according to the assignment requirement. Therefore I know more about the network topologies such as star topology, bus topology and others. And I've go on in contact with network media such as UTP cable, coaxial cable and others. Our networking information is improved a lot because of as I describe. However, during learn about the network topologies and network media, I have a lot of difficulty to know because they are not familiar with me. So I try to discover on the internet and I request the facts to our lecturer that I do not understand. After asking many times and many time, our problems are clearer and understandable. The disadvantages of star topology are that it needs more cable length than a linear topology. If the central device like hub, switch, or concentrator fails, nodes are removed from the network. The cost of the hub (or) switch is expensive so the star topology is expensive, etc. The advantage of star topology is that it is simple to install and set up cable. No disturbance to the network when adding or taking out devices and detect error and take out element.

After that, I seek to look to solve the task 2. I have to talk about the police station that I've not ever been. However, I try to look for the police station work information on the internet for police station responsibility and why police station needs such internet connection speed. I also talk about the information every time when I got information and decide which would be acceptable facts for the police station and which facts would be removed. During study about the police station work, I know police station work improved and improved. After studying the police station work information, I try to search Internet Service Provider (ISP) for the police station and I found two Internet Service Providers in our country. And I check main point of connection speed and price form those ISP. Therefore I have a good knowledge about the Internet Service Provider (ISP).

After that, I seek to explain which two-way voice communication is appropriate for police station. I saw walky talky which are held by the policeman but I did not know how PTMR operate very well. So when I see two-way voice communication, I thought that would be GSM technology. But I know that it cannot be GSM technology when I read requirement carefully. So I had to read the books about the Public Trunked Mobile Radio (PTMR), finally I know about the Public Trunked Mobile Radio (PTMR) well and I also had to find out GSM technology and learn about the basic knowledge of the GSM ,too. It is not expensive than Global System for Mobile Communication (GSM). And Public Trunked Mobile Radio (PTMR) is suited to vehicle feet communications. For police car, the Public Trunked Mobile Radio (PTMR) is useful when the crimes occur. If the crimes such as murder happen, the police car calls other squads for more help. Public Trunked Mobile Radio (PTMR) data rate is 2.2kbps but low throughput. Not only trunking frequencies need licensing but also the process is slow. Improved employment of frequencies by sharing all channels and frequencies which are licensed protects mobile component against outside obstruction. Consistency is improved because network is more tolerant to error. Accessibility is certainly improved than mobile radio because more available channels and can use diverse configurations to enhance system operation.

The price is pretty high due to more complicated trunking equipment. I found private branch exchange (PBX) and Key Telephone System (KTS) may suitable for the police station requirement. So I study which system is the most suitable for the police station. And I found Key Telephone System (KTS) is only suitable with the small organization. I think police station is not like the small organization and police member telephone line can be extending depending on the city population and I found private branch exchange (PBX) system is the most suitable for the police station if telephone lines are going to extend. The main disadvantage of a private branch exchange (PBX) service, is that it is dependent on the Internet connection. Although the regular corporate Internet connection is very trustworthy, there is the threat of network problem, a virus or other disruption taking the police offline, even for a short time. While the user contact with the failure of their Internet service for a little while, being unreachable by phone is harder to swallow for the user even for an hour. Devoted telephone hardware is set up to be totally consistent and, small of a building crew cutting the phone lines outside the police building, will hardly ever suffering an outage. Our knowledge about the two-way voice communication is improved a lot because of this assignment.