Computer Sciences - - Assignment Example

Computer Sciences and Information Technology  Year: Question A Transmission Control Protocol (TCP) is a protocolthat facilitates the transportation of data across a network. In network communication, many layers are involved in the movement of packets from one host to another. These layers all have different functions that help with the movement of packets. These layers are under the Open System Interconnection (OSI) model, and they are broken down into the following layers; physical, data link, network, transport, session, presentation and application.

These have been listed from the Network interface card to the computer interaction interface. These layers show how a data packet travels from one host to another, when it has been sent from a computer interface, for example, an email sent from a computer browser. It is encapsulated and changed into different forms until it reaches the network interface card in the physical layer, where it is sent as a signal, and the process of conversion takes place again. The result for the viewer is the email on the browser (Tanenbaum 86).

Many processes take place in the different layers to facilitate this communication. The Transmission Control protocol takes place in the transport layer of the OSI. This layer facilitates the transmission of packet using different communication protocols. This is done with accordance to the type of data and the communication/connection type. There are different types of protocols for handling this function. The TCP protocol uses a method called ‘handshake’ (Tanenbaum 92). In this method, the packet sends a request to the receiver, to query if it is able to receive the packet before it sends it.

When the packet has been sent to the receiver, the host has to give an acknowledgement that the packet has been received. When sending these packets, an IP address of the source is attached to the data segment and the destination host IP address. This is to confirm that the requesting host is the one that sent the data. It is also done for the reverse process. For this question, when the Host A has the source port number x and the destination port number y (Tanenbaum 213). When segments are travelling from Host B to Host A, the source port number is y, and the destination port number is x.

because the sender is now the receiver of the data segment. Question 2 In the transport layer of the OSI model, another method of Internet Protocol communication is the User Datagram Protocol (UDP). The factor that brings the difference between UDP and TCP is that UDP does not have the handshaking feature. This means that, in the UDP protocol, the packets do not need to query for permission before they start transmitting. When the packets have been sent, they do not need to send acknowledgements to the transmitter.

This can be viewed as problematic because some packets can be lost along the way and they will not be re-transmitted. For sensitive information, this can lead to data losses or corrupted packets received at the receiving host. The use of UDP always leads to dropped packets, duplicated packets, or incomplete packets at the receiver (Palmer 214). This protocol is useful for systems or applications that require real time data, or applications that would rather drop packets as a way for acknowledgement or re-sending of delayed packets.

This is used in time sensitive applications. This can provide reliable data transfer on an application that is running over a UDP network (Palmer 215). This is essential, as previously stated, for applications that do not require the resending of dropped packets. For example, when streaming a movie or a video, UDP would be more reliable as the data will be received in real time, without waiting for acknowledgement before sending. The dropped or lost packet for high volumes of data transfer like this will be almost negligible.

UDP also provides reliable data transfer over networks that require broadcast or multicasts of data (Palmer 216). Question 3 The TCP connections are designed towards reliability over time concerns. The protocol ensures that the data is delivered reliably over the network. This is with the acknowledgement mechanism where the data has to be acknowledged before it is sent. These other mechanisms that ensure reliability are the error checking mechanism which checks every packet that is received for errors in the data composition (Forouzan 111).

In the scenario where two TCP connections are present over some bottleneck, and both connections need to send a huge file, the connection will share the available transmission rate. This kind of bottleneck scenario usually results in reduced data transmission rates. The bandwidth allocated has to be shared among all the available connections. This will happen if the files are to be sent at the same time. The transmission rate R bps will be shared between the two connections so that each connection will send the file with R/2 bps (Forouzan 112).

References Forouzan, B 2003, TCP/IP Protocol Suite, McGraw Hill, New York. Palmer, M 2006, Hands-On Networking Fundametals, Cengage Learning, New York. Tanenbaum, A 2003, Computer Networks, Prentice Hall PTR, New York.