Computer Science 代写：网络拓扑结构和操作论文

In this task I will make home network (LAN) for fire department so we can use cable network topologies or Wi-Fi network topologies. If we are use cable network topologies then we get bus network and star network and we are use wireless network then we get AP-based topology (Infrastructure Mode) and Peer-to-peer topology (Ad-hoc Mode) and I show all network each medium describe.

Network topologies

Network topology refers in the direction of the computer network is agreed. The network is physical topology or logical topology. The physical topologies describe the layout of computer and where the workstations be placed. The logical network topologies describe how the data flows through the network.

Reference

http://www.wisegeek.com/what-is-a-computer.htm

A. Topology operate

Cable network  Ethernet technology  BUS & STAR TOPOLOGY

Bus topology operation

The bus topology connects every computer on the network into impressive called the segment trunk. A bus is typically referred to a cable that connects end to end and this is use to send out the signals from one end to the other end. Each end a terminator is placed so that it understand in which track the data is traveling and also the terminator is used to take in the signals. The bus is careful to be an active network because the computers are mostly independent on the signal that is being transmitted.

Figure-Bus topology

Reference

http://fallsconnect.com

Star topology operation

Star Topology is common type of network topology that is use in home and office. Star Topology there is a central connection point called the hub which is a computer hub or sometimes just a switch. Star network is use the UTP or the unshielded twisted pair cable. Another common cable that is used in star networks is the RJ45 or the Ethernet cables. Star Network the whole network is reliant on the hub so if the whole network is not working then there could be a problem with the hub. This attribute make it simple to troubleshoot by offering a single point for error connection ad at the same time the dependence is also very high on that single point.

Figure-star topology

Reference

http://fallsconnect.com

Wireless network topology

AP-based topology (Infrastructure Mode)

Peer-to-peer topology (Ad-hoc Mode)

AP-based topology (Infrastructure Mode)

The clients communicate throughout Access Point.

BSA-RF coverage provide by an AP.

ESA-It consists of 2 or more BSA.

ESA cell include 10-15% lie on top to allow roaming.

Figure-WLAN (infrastructure mode)

Peer-to-peer topology (Ad-hoc Mode)

AP is not essential.

Client devices within a cell can communicate directly with each other.

It is useful for setting up of a wireless network quickly and easily.

Figure-ad-hoc

B. pros and cons of each medium

Cable network topology

1. Twisted pair

2. Fiber optics

Advantage of twisted pair

cheap and readily available

Flexible and light weight

Easy to work with and install

Disadvantage of twisted pair

vulnerability to interfering and noise

reduction problem

analog, repeaters considered necessary each 5-6km

digital, repeaters considered necessary each 2-3km

Advantage of fiber optics

exceptionally high bandwidth

simple to contain rising bandwidth

Resistance to electromagnetic interference

Disadvantage of fiber optics

setting up costs, whilst dipping, are still high

particular test tools is often required

vulnerability to substantial damage

Radio wave frequency

Radio waves are a type of electromagnetic waves. Radio wave has an a lot longer wavelength than does detectable light. We make use of radio waves expansively for connections. Naturally-occurring telephone system influence is made by lightning, or by exorbitant objects. Synthetically-generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems.

Wi-Fi technology

Wi-Fi network make use of Radio technology to transmit & accept numbers at high speed:

IEEE 802.11a

IEEE 802.11b

IEEE 802.11a of advantage

Operates at 5 GHz (less popular)

54 Mbps (theoretical speed)

15-20 Mbps (Actual speed)

IEEE 802.11a of disadvantage

50-75 feet range

More expensive

Not compatible with 802.11b

It does not support encryption

IEEE 802.11b of advantage

Operates at 2.4GHz radio spectrum

11 Mbps (theoretical speed) – within 30 m Range

C. Own recommendation

In this section, I have to recommend which type of networks & which topology are acceptable for an in-house network and I have described both ‘cable network topologies'(BUS & STAR) and ‘wireless network topologies'(ad hoc & infrastructure) and also motioned the advantages and disadvantages of ‘Twisted pair & fiber optic’ cables and ‘802.11a & 802.11b’ standards for the wireless technology (Wi-Fi). And finally I have chooses the ‘Wireless Network’ in which the ‘Wi-Fi technology’ will be used and the 802.11b standard for communication purpose because it supports encryption for data transmission.

Figure-wireless networking

Task-2/marks-10

A. Choose Internet Service Required (VPN)

In this task we will investigate internet connection required for Fire Department but we read Fire Department all necessary information in scenario. Mainly this Fire Department coverage area 70 square kilometers and Fire Department control centre has three controllers on duty at a time who receive call from the public and other emergency services. Control center receive information sends details to a printer then print copy provide fire officer then fire officer leaves the building and attend the incident.

So we thought that control center emergency information receives and print in this whole work we chose Virtual private Network (VPN). Virtual private Network (VPN) use in public network but it is use for privately own work.

When fire department all branches connect in VPN network then headquarter and control center and civilians staff area all necessary information send any branch is possible at any time so fire department all work will be very easy. Fire department printer will add in VPN network then control center all public news and fire officer can be print and attend the incident.

I:\Virtual_private_network_files\330px-Virtual_Private_Network_overview.png

Reference

Own opinion

B. Suitable connection speed

1 mbps connection speed suitable for these requirements because fire department only three religional offices and this office only use data communication and emergency incident location information receive and print by in this VPN network and emergency file shear branch to branch and when need remote access each branchs. So 1 mbps connection speed is sufficient for Fire Department.

Reference

Own opinion

C. Internet service provider (ISP) in my country

1. Asia net limited

Asia net limited is Internet Service Provider who provides high quality communications services to many office and homes.

Asia net limited offer

Corporate, SME, Residential & Reseller (Fiber to the last mile).

Corporate Virtual Private Network (VPN) solutions.

Server collocation and Bandwidth Service.

Reference

http//www.asianetbd.com

2. Aftab IT Limited

Aftab IT Limited is one of the top Internet and Intranet Service Provider in Bangladesh. Aftab IT can offer its clients the required level of services that have stability, security, reliability and network coverage.

Aftab IT Limited offer

Corporate Broadband Solution

Dial Up Internet Solution

VPN Solution

Reference

http//www.aftabitlimitedbd.com

3. BDCOM limited

BDCOM is an internet service provider in our country.

BDCOM limited offer

Shared Bandwidth

Dedicated Bandwidth

Leased Bandwidth

On-demand Bandwidth

Reference

http//www.bdcom.com

D. Recommendation on ISP and price charged

Asia net is a very large internet service provider (ISP) in our country and their facilities and service is high-quality and all time technical supports and service charged is better from other company.

Price charged

Service provider

Time

Speed

Download/upload

Taka

Dollar

duration

installation

Asia net

24Hours

1MB

896/896kbps

2550

$25

Per Month

Free

Aftab

24Hours

1MB

896/896kbps

2640

$26

Per Month

Free

BDCOM

24Hours

1MB

896/896kbps

2700

$27

Per Month

Free