The Types Of Available Network Topology Computer Science Essay

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In the question one, the question is require to ask to define what is topology. Besides that, the question also is require to explain types of topologies and the last is to require user to recommend what is best suitable network topology for the small networking office. Besides that, topology is very important for now.

What is meaning of topology? Actually, topology is arrangement of network for different type of network topology. Network topology connects to the computer through using cable. Besides that, network topology can be defined in two ways which are physical and logical. Physical topology is can be defined as design of the network topology and logical network topology can be defined as how the data be transferred in network topology. Besides that, different type of network topology also contains different advantages and disadvantages.

There are few most common types of network topologies which are bus topology, star topology, ring topology, tree topology and mesh topology. These few types of topologies are used by nowadays' network. Different of topologies also contain different of design of network topology and arrangement of the network topology.

First, let's discuss about the bus topology. Below is the picture of bus topology.

Bus-Network-Topology.png

Diagram 1.1

(Source: Anonymous, 2010, bus topology, viewed on 28th October 2010 http://www.edrawsoft.com/images/network/Bus-Network-Topology.png)

Bus topology is a quite simple network topology. Bus topology is connecting few of computers through a single linear. That linear also can know as backbone, but bus topology is using a common backbone to connect those computers. Bus topology also is a multipoint transmission medium. All the computers share a communication through a bus topology. Bus topology is only allowed one computer to transmit the signal in a specified direct of time. Bus topology also is a type of full- duplex connection. The bus topology contains four types of alternative media that can available in bus topology. These four types are twister pair, baseband coaxial cable, broadband coaxial cable and optical fiber. When the bus topology has transmitted a signal, then the end of the bus topology should be terminated. The terminator is to prevent the signal wouldn't absorb back to bus topology.

(Anonymous, What is topology, 2010)

Besides that, there are some advantages and also disadvantages of the bus topology. First, let's discuss about the advantages of the bus topology. There are few disadvantages of the bus topology. The first advantage of the bus topology is once one of the computers has breakdown and it also wouldn't affect other computers and it can be continued. The second of the advantage of the bus topology is bus topology is easy and fast to be installed and it is very fit of to be impermanent network topology. The third advantage of the bus topology is bus topology has used the less cable to spend up less cost.

Besides that, there also some disadvantage of the bus topology. The first disadvantage of the bus topology is bus topology cannot cover well when there has occurred traffic jam. The second advantages of the bus topology are when the bus topology of common backbone has breakdown then the other computer cannot communicate with each other.

(Behrouz A. Forouzan, Data Communications And Networking, 2010)

Second one is about the star topology. Below is the figure of the star topology.

star.jpg

Figure 1.2

(Source: Anonymous, 2010, star topology, viewed on 28th October 2010, http://www.cs.umd.edu/class/fall2001/cmsc411/proj01/pub/figure2.jpg)

Star topology is a network topology that the entire computers are to connect to the central node. As from the above the figure 1.2, the canter one is called as central computer. The central computer is to control the communication between each of the computer. Besides that, the central computer also can act as switch node. In nowadays, the star network is mostly used by house and office. Besides that, the central node is only allowing one computer to transmit the signal in one time. If there are two computers are transmit the data at the same time then it will caused delay. The node will transmit the data to the central computer. The start networks currently are using twisted-pair or the optical fiber as wiring.

(Anonymous, What is topology, 2010)

Besides that, there are also contain few types of advantages and disadvantages of the star topology. First, let's discuss about the advantages of the star topology. There are some advantages of the star network which first of the advantage of the star topology is the star topology is very easy be installed it. Besides that, the second advantage of the star topology is the star topology is very easy to control and expand. Another advantage of the star network is if one of the nodes is breakdown and it wouldn't to other nodes too and the other node can be worked by normally.

Besides that is about the disadvantages of the star topology. There are some disadvantages of the star topology too. The first disadvantages of the star topology are all the nodes are too reliable to the central computer. If the central computer is breakdown then the whole network will also going to breakdown too. The second advantage of the star topology is the maintenance fee of the star network is quite expensive.

The third network topology is about the ring topology. Below is the figure of ring topology.

ring.gif

Figure 1.3

(Source: Anonymous, ring topology, viewed on 28th October 2010, http://www.studynotes.net/net1.htm)

Let's discuss about the ring topology. Ring topology is a network topology that a computer is going to connect to the second computer and the second computer will connect to the third computer and the computer will connect back to the first computer within a loop. It means that each of the computers must contain two of neighbour to transmit the data. Besides that, in the ring topology, there are doesn't have termination for the ring topology because the ring topology does not contain of terminator and the ring topology will keep loop and loop. After the computer has received the packet then it will retransmit to another computer.

(Behrouz A. Forouzan, Data Communications And Networking, 2010)

Besides that, the ring topology also is allowing the network to transmit the packet in one direction by whether is clockwise direction or anti-clockwise direction. To let the ring topology to work with normally, there are three types of the function to provide to ring network and those three networks are data insertion, data reception and also data removal.

There are some advantages and disadvantages of the ring topology. Let's discuss about the advantages of the ring topology. The first advantage of the ring topology is the packet is transmitting to other computer with speedy. Another advantage of the ring topology is can load heavy network while transmitting packet to other computer.

Next is about the disadvantages of the ring topology. There are some disadvantages of the ring topology and the first disadvantage of the ring topology is about the computer. If one of the computer has breakdown and the whole network will be breakdown too. It means that the ring topology wouldn't transmit packet anymore. The second disadvantage of the ring topology is when the ring topology has to increase one or more computer then the whole network has to close and after set up a new computer only can open back the network. If close the ring topology and it mean that the whole network has to stop. So it maybe would be because some trouble.

(Ahmad, Data Communication Principles for Fixed and Wireless Networks, 2010)

Next is about the tree topology. Below is the figure of tree topology.

tree_topology.gif

Figure 1.4

(Source: Anonymous, tree topology, viewed on 28th October 2010, http://chauncy-ict.pbworks.com/f/tree_topology.gif)

Actually, tree topology is the combination of the bus topology and the star topology. From the above figure, the structure just like the star network is connecting to the other star network. Tree topology also is considered as hybrid topology because it contains more than two of topology. The most centre one, is the root of the computer. Tree topology contain network that with speedy.

There are some advantages and disadvantages of the tree topology. Let's discuss about the advantage of the tree topology first. The advantage of the tree topology is the tree topology has solved the insufficient of star topology. Another advantage for the tree topology is a point to point is available in the tree topology.

(Ahmad, Data Communication Principles for Fixed and Wireless Networks, 2010)

The last topology is the mesh topology. Below is the figure of the mesh topology.

mesh.gif

Figure 1.5

(Source: Anonymous, mesh topology, viewed on 28th October 2010, http://oreilly.com/catalog/lgscalelans/chapter/dlsl_0304.gif)

Above of the diagram is structure of mesh topology. Mesh topology is a topology that the entire computers are connecting to each other. Mesh topology is also creating a point to point connection.

There are some advantages of the mesh topology. The first one is mesh topology will transmit the signal to reach the destination with the fastest route. So, the mesh topology is containing of lesser breakdown than to other topology. Besides that, if there are one of the computers has been breakdown and the mesh topology still can work by normally.

There are some advantages of the mesh topology. The first disadvantage of the mesh topology is the installation of the mesh topology is needed to spend up so much cost. Because of the cable that use by mesh network is very much. The second advantage of the mesh topology is the installation of the mesh topology is very hard and complex.

In the last, I choose star topology as their network topology, because the star network is suitable for the house or the small network. Besides that, the star topology is very easy to installed and easy to manage by the office.

(Bhakti Satalkar, Mesh Topology, 2010)

After this question, I have learned about the different type of topology also got they own different arrangement and shape of design. Different types of topologies also contain different advantages and disadvantages too. Topology can be implementing in different place. Not every type of topology also can apply at a same place.

Hope at the future can see more hybrid network topology.

Introduction Q2

The question two is to require explaining some function of the data link control. The purpose of data link control is to provide some functions which are flow control, error detection and also the error control. Different function also contains of different its own method.

First, let's discuss about the flow control. Flow control is to make sure the sending unit do not overcome the receiving unit. This also is prevent the buffer will overflow. Besides that, there are two methods which contain by flow control that can to control the overflow. These two methods or techniques are stop and wait flow control and the other one is sliding window flow control.

Let's discuss another technique in the flow control function. The second technique of the flow control function is known as sliding windows flow control. Sliding window flow control is can transmit packet of frame in one time. In this sliding windows flow control, the sender sends the packet of frame and receiver receives the packet of frame. After that, the receiver no need send the acknowledgement to the sender but the sender is already can send the next packet of frame to the receiver. Besides that, each of the frame also contain of number. When the receiver sends the acknowledgement, the acknowledgement is already including the number.

(Yang, Information Processing and Routing in Wireless Sensor Networks, 2010)

Secondly, let's discuss about the error detection which is one of the function of the data link control. What is error detection? Error detection is the frame that detects some error inside the code of frame. There are two techniques to detect error. These two of the techniques or methods are parity and CRC which is also known as Cyclic Redundancy Check.

First, let's discuss about the technique of parity. Parity is the technique that about 1s and 0s in the code. Besides that, the value of code is only contain even or odd number in the bit. If the bit of codes is even number than the error will undetected. But, if the bit of code is odd number, then the error will appear. Then the bit will add 1s to let it between numbers of even and then problem is already solved.

Secondly, let's talk about the CRC which is also known as Cyclic Redundancy Check. Cyclic Redundancy Check is if the number is divided by a number. After that, the number that be divided has appear reminder. Then the error will appear. The remainder will be adding up to the original code and then it will be divided by the same number again. After that, if the number that be divided is no more reminder, then the error will disappear.

(Yang, Information Processing and Routing in Wireless Sensor Networks, 2010)

Next is discussing about the function of error control. What is the function of the error control? Function of error control is to detect error and to correct the error. It will reject the damaged frame. There are three type of ARQ which is standing by Automatic Repeat Request. What is the function of ARQ? Automatic Repeat Quest is will help to transmit again the frame if the frame is lost in the middle way to send to the receiver. Besides that, the Automatic Repeat Quest also will to detect the error and will process positive acknowledgement. The three type of Automatic Repeat Quest are Stop and Wait ARQ, Go Back N ARQ, and also the Selective Reject. These three types of Automatic Repeat Request also is the technique of the function of error control.

(Yang, Information Processing and Routing in Wireless Sensor Networks, 2010)

At first, let's discuss about the Stop and Wait ARQ. Stop and wait ARQ's concept is almost similar with stop and wait. Stop and wait ARQ is also the sender sends the frame to the receiver. After that, the receiver will send the acknowledgement to the sender that informs the sender that the receiver has received the frame so that the sender will send the next frame to the receiver. Besides that, if the frame that transmit to the receiver has lost or damaged then the stop and wait Automatic Repeat Request will throw away the lost or damaged frame. The transmitter contain of time limit. If the acknowledgement didn't send back to the sender in the time limit, then the stop and wait ARQ will automatically to request the sender to send the same frame to the receiver again.

By the way, if the acknowledgement that send to the sender has lost or damaged, then the ARQ also will request receiver to resend the acknowledgement to the sender. In this case, the receiver will receive the same two frames from the sender. Below is the example of the wait and stop Automatic Repeat Request.

Figure 1.1

(Source: Anonymous, Wait and stop ARQ, viewed on 29th October 2010)

Next is discussing about the Go Back Automatic Repeat Request. Go Back N ARQ is similar with sliding windows. Go back N can transmit the frame with packet by packet. The sender receives the packet of frame and one of the frames is getting damaged and the receiver will send the rejection of the damaged frame. After that, the sender will receive the rejection from the receiver and then the senders will retransmit the same packet of the frame which includes the frame that reject by the receiver. Besides that, if the frame is get lost in the middle way of to transmit for the receiver, then the sender will transmit the frame with plus one. The receiver will receive the frame with plus one and then will reject the frame. After that, the sender will retransmit the frame to the receiver.

If the sender cannot send the frame in the time of limit, then the sender will the acknowledgement frame while P bit set as 1.

Below is the example of Go back N AR

.

Figure 2.2

(Source: Anonymous, Go Back N ARQ, viewed on 29th October 2010)

Next let's discuss about the third technique of error control which is selective reject. It is also same like sliding windows which can send the packet of frame to the receiver. If the one of the frame from the packet of frame has reject from the receiver, then the sender will just only to retransmit the rejected frame to the receiver. The following frame will receive and buffer from the receiver.

Below is the example of the selective reject.

Figure 2.3

(Source: Anonymous, selective reject, viewed on 29th October 2010)