# Bus Topology Star Topology Computer Science Essay

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In computer networkingÂ topologyÂ refers to the layout of connected devices. So it includes the way that cables and other pieces of hardware connect to one another. We can simple describe the topology as the way that computers are connected. Computer network topologies can be categorized in the following categories.

According to this topology all devices are connected to a central cable called theÂ bus orÂ backbone. Common backbone is which that bus topology uses to connect all the network devices in a network in a linear shape. So this is how bus topologyÂ connects each computer on the network into the segment trunk.Â This was generally implemented using coaxial cable during the 1980's.According to this network topology single cable functions as the shared communication medium for all the devices attached with this cable with an interface connector.

The signal travels from one end of the bus to the other. At every end a terminator is placed in the cable. A terminator is required at each to absorb the signal so as it does not reflect back across the bus. Normally a true bus network considered to be a passive network because the computers are largely dependent on the signal that is being transmitted. In a Bus Topology a signal is broadcast to all modes, but only the destination node responds to the signal. Bus topology can represent as follows,

bus.JPG

Figure

According to this topology if break part of the cable or remove the terminator, all machines on that segment lose communication with the network. When consider about this topology we can identify that traffic generated by any computer will travel across the backbone and be received by all workstations.

So when the number of computers increases network traffic can greatly decrease the performance and available bandwidth of the network. however to the bus topology it is easy to add devices or delete them from the Network as devices are simply daisy chained along the Network Bus. Bus Topology is most appropriate when the linked devices are physically close to one another.

## Advantages of a Bus Topology

Easy to connect a computer or peripheral to a linear bus.

Requires less cable length than a star topology

Well suited for temporary networks

Good for smaller networks not requiring higher speeds

Quick setup

Less expensive than a star topology due to less footage of cabling and no network hubs

Easy to implement and extend.

## Disadvantages of a Linear Bus Topology

Entire network shuts down if there is a break in the main cable.

Terminators are required at both ends of the backbone cable.

Difficult to identify the problem if the entire network shuts down.

Not meant to be used as a standalone solution in a large building.

One host can transmit at a time.

Don't react well to more and more hosts being added.

The most hosts we have on a bus, the more collisions we have. So more retransmissions

Maximum data transfer speed is 16mbps

Maximum 200m.

If two PCs are communicated the PC on either side will not be able to communicate.

One bad connector can take down entire network

Maintenance cost may be higher in the long run.

As the number of computers increase in the network the data transfer rate goes down

## Reference:

http://homepages.uel.ac.uk/u0116771/bus_topology.htm

http://en.wikipedia.org/wiki/Bus_network

## Star Topology

Star topology consider as the most commonly used topology in LAN of computer networking world. The idea of star topology comes from Telecommunication system.Â Â In telephone system all telephone calls are handled by central switching station. Here all the computers in the star topologies are connected to central devices like hub, switch or router. It involves a centralized host Computer connected to several other Computer system which are usually smaller than the host.

star.JPG

Figure

However star network requires more devices & cables to complete the network. However failure of each node or cable in a star network won't take down the entire network. But this is a Central type of failure type network. If the main switch or the hub was gone entire network will down. Star topology is very easy to extend and modify the network. It is easy to install and manage. In the same time due to the centralization in star topology it is very easy to monitor and manage the network.Â So according to the star topology all wiring is done from a central point while supporting the greatest cable lengths of any topology. Also in the star topology fail of singleÂ computerÂ will not affect the whole network.

According to the star topology procedure it prevents the passing of data packets through an excessive number of nodes. Each device is inherently isolated by the link that connects it to the central point. So this makes the isolation of individual devices straightforward and amounts to disconnecting each device from the others and in the same time increases the size of the network very easily if the network has implemented according to the stat topology because of centralization feature in the star topology. In the same time it is really easy to understand, establish and navigate. Not only that star topology has a number of concentration points. These provide easy access for service or reconfiguration of the network. However the topology is high dependence of the system on the functioning of the central hub and these topologies implementations are a little more expensive.

## Advantages of a Star Topology

Better performance

Isolation of devices

Benefits from centralization

Simplicity

Easy to understand

Easy establish

Ease of service

No disruptions to the network when connecting or removing devices.

Easy to detect faults and to remove parts.

More connect more computers than other topologies

More suited for larger networks

Easy to expand network

Cabling types can be mixed

Due to its centralized nature the topology offers simplicity of operation

Reliable

if one connection fails, it doesn't affect other computers

High data transfer speed(100mbps)

## Disadvantages of a Star Topology

Requires more cable length than a linear topology.

When the main connector fails the Entire Network system will be down.

Expensive than other topologies

## Reference:

http://www.computerhope.com/jargon/s/startopo.htm

## Ring Topology

Ring topology is a network within which all computers are connected like in a circle. So all devices are connected to one another in the shape of a closed loop, So each device is connected directly to two other devices, one on either side of it in this topology data transmission is depending on a token. In ring Network every computer or devices has two adjacent neighbors for communication in the same time all the communication messages travel in the same directory whether clockwise or anti clockwise. In this topology also any damage of the cable of any cable or device can result in the breakdown of the whole network.Â

ring.JPG

Figure

When we concern about the process of ring topology, we can identify that ring topology is used token ring networks. Each device processes and retransmits the signal, so it is capable of supporting many devices in a somewhat slow but very orderly fashion. To transfer the token or the small data packet, it continuously passed around the network.

When a device needs to transmit, it reserves the token for the next trip around and then after attaches its data packet to it. The receiving device sends back the packet with an acknowledgment of receipt. Then the sending device puts the token back out on the network.

This is how ring topology functions. This topology is easy to expand and can create much larger networks using token ring and no need of terminators for the network. But these networks performance will depend according to the number of the computer. When the number of the computer become high , performance of the network minimize. In the same time cable breaks and failure of the computer can lead as a reason for the entire network down.

## While considering all these above things and by go through the ring topology we can present following advantages and disadvantages of the ring topology in point form as follows,

Easy to expand

Can create much larger network using Token Ring.

Every device has access to the token and the opportunity to transmit

No terminators required

According to the number of computers performance of the network will depend

If the cable break whole network will down

Moves, Add and Changes of devices can affect the network.

Much slower than an Ethernet network under normal load.

Failure of one computer can affect the whole network.Â

It is difficult to troubleshoot.Â

## Reference:

http://it.toolbox.com/wiki/index.php/Ring_Topology

## Tree Topology

A tree topology combines characteristics of linear bus and star topologies. Normally this topology consists of groups of star configured workstations connected to a linear bus backbone cable. Only the hub devices can connect directly with the tree bus and each Hub functions as a root of a tree of the network devices.Â So tree topology occurs when multiple star topologies are connected together such that not every node is directly connected to a central hub. That's why we can derive thatÂ the TreeÂ TopologyÂ is a combination of the bus andÂ the StarÂ Topology.

Figure tree.JPG

This topology is particularly helpful for colleges, universities and schools so that each of the branches can identify the relevant systems in their own network and yet connect to the big network in some way. Because treeÂ like structure allows to have many servers on the network and can branch out the network in many ways. TreeÂ TopologyÂ is supported by many network vendors and evenÂ hardwareÂ vendors and in the same time point to pointÂ connection is possible with Tree Networks. However TreeÂ TopologyÂ network isÂ big. So it is difficult to configure and can get complicated after a certain point even though it is entirely dependent on trunk. So If it has fail entire network would fail.

## Advantages of a Tree Topology

Point to point wiring for individual segments.

Point to pointÂ connection is possible with Tree Networks.

Supported by several hardware and software venders.

All the computers have access to the larger and their immediate networks.

Good to branch out networks.

## Disadvantages of a Tree Topology

More difficult to configure and wire than other topologies.

More difficult to configure and wire than other topologies.

If the backbone line breaks, the entire segment goes down.

Overall length of each segment is limited by the type of cabling used.

Entirely dependent on the trunk

## Reference:

http://fcit.usf.edu/Network/chap5/chap5.htm

http://www.exforsys.com/tutorials/networking/tree-topology.html

## Mesh Topology

Mesh topology is a type of network setup where each of the computers and network devices are interconnected. Mesh topology work on the concept of routes. According to tihs topology message sent to the destination can take any possible shortest and easiest route to reach its destination. So it offers superior redundancy and reliability. In a mesh topology each computer is connected to every other computer by separate cabling. So this configuration provides redundant paths throughout the network.

Because of that if one cable fails, another will take over the traffic. This technology consider as more beneficial because of its backup capabilities by providing multiple paths through the network. This type of topology is not commonly used for most computer networks as it is difficult and expensive to have redundant connection to every computer. In the same time it ensures the data privacy or security, because every message travels along a dedicated link. However these topologies are very expensive because a large number of cabling and 110 ports are required and in the same time these type of topologies are difficult to install.

mesh.JPG

Figure

## Advantages of a Mesh Topology

Ensures the data privacy or security.

Troubleshooting is easy as compared to other networks.

Its performance is not affected with heavy load of data transmission.

Each connection can have its own data load.

Expensive

Difficult to install.

Complex topology

## System administrator & users and the IDM network

There are number of roles take in place of a network. Among those roles we can identify two main roles who are directly enroll with the network.

## 2. User

System administrator also known as systems administrator orÂ sysadmin. System administrator is a person employed to maintain and operate aÂ computerÂ system or network. We can say that system administrator is a supreme being who maintains and troubleshoots the computer systems. While considering all these things we can simply say that system administrator is the person who manages and maintains computer systems and software, as for a business or institution.

Normally Â systems administrator needs a fairly extensive knowledge of various computer operations to be effective. So he or she must understand how theÂ mainframeÂ server operates and know how to maintain the computer system, install software and patches, resolve problems, maintain data files, monitor the system and execute systems backup and recovery.

Because of these reasons we can simply define that systems administrator should know how to do nearly everything the system requires for maintenance. A good systems administrator keeps things working smoothly day to day while trying to grow with the job and improve the way the organization uses technology. There are number of functions we can identify as the functions which are handle by a system administrator.

D:\Program Files\Microsoft Office\MEDIA\CAGCAT10\j0302953.jpg

When we consider about the system administrator within the IDM network we can identify few day today task performed by system administrator as follows,

Performing backups

Adding and deleting new network users

Making sure that virus protection software is up to date, and cleaning any viruses that infect staff computers

Training and assisting staff in using hardware and software efficiently

Troubleshooting any routine problems

Planning for and responding to service outages and other problems.

As daily basic system administrator handle these task to maintain more advantagerable network and to provide more quality service to the users who are involved with the network.

System Administration privileges are really important to handle system or a network. When we talk about the privileges of the System administrator we can say that,

System administrator privilege's can mostly equal to the privileges of a owner of own computer .Which means System Administrator has well privileges. We can clear identify when we concern about the idm network handling process.

## Responsibilities of a system administrator

When we go through out the role of the System Administrator, we can identify that there are such number of responsibilities to handle . Here are few responsibilities that we can identify when we go through out the IDM network such as,

Research and troubleshooting

Database supervision

Protecting the user's privacy to the fullest extent possible.

Back up and recovery for critical data

User support

Network monitoring

Equipment maintenance

Standard security settings

AnalyzingÂ system logsÂ and identifying potential issues with computer systems.

Introducing and integrating new technologies into existingÂ data centerÂ environments.

ApplyingÂ operating systemÂ updates, patches, and configuration changes.

Installing and configuring newÂ hardwareÂ andÂ software.

Ensuring that the network infrastructure is up and running.

Normally a system administrator is responsible for these responsibilities. So we can identify this role as more responsible role plays in a network.

## Users

Users are the people who always move with the network. Normally network environment resources are shared equitably among users. When we concern about the IDM network we can identify that the students are the main users of the network.

However we can say that IDM staff members and all are become a part of the users of the network. Only a System administrator can't handle better service within a network. So the users support is really important to handle a better manageable network. That's why we can say that users also have some part to cover in their way.

## Users Privileges

According to the IDM procedure network service is provided for staff and students of the IDM to undertake their duties and studies related to the operations and mission of the IDM.

## we can identify these things as responsibilities of the users ,

Better disciplinary

Respects the computer use guidelines for connected networks.

Free of illegal or malicious acts

Users are responsible for proper password maintenance,

Protect the resources

Provide their fullest support for a better network management

Self behavior management

Responsibility of own works

Do not engage in unauthorized duplication, transmission, alteration or destruction of data, programs or software.

Not use computing resources for commercial or profit-making purposes without written authorization.

## Conclusion

So while considering all these this we can come to an conclusion to that System administrator lays a main role in a network to maintain the network with high quality performance while providing a better service. To maintain a better and more quality servicer users support is also needed.C:\Documents and Settings\Poornima Senarathne\Local Settings\Temporary Internet Files\Content.IE5\E9CCKNGB\MPj04393590000[1].jpg