PROGRESS 1

OSI Layer Model

Application layer:

This is the only layer that directly interacts with data from the user. In this case, software applications like web browsers such as Google Chrome and Microsoft Edge rely on the application layer to initiate communications. For example, when a student requests content in ULearn such as a lecture note, this application session will return the content “lecture note” to the student. But it should be made clear that client software applications are not part of the application layer, rather the application layer is responsible for the protocols and data manipulation that the software relies on to present meaningful data to the user. Application layer protocols include HTTP.

 

Presentation layer:

 

This layer is primarily responsible for preparing data so that it can be used by the application layer, in other words, presentation makes the data presentable for applications to consume. The presentation layer is responsible for translation, encryption, and compression of data. Two communicating devices communicating may be using different encoding methods, For example in this case when a student request a file in ULearn, the data will go through a different type of translation, encryption and compression before going to the application layer, so presentation layer is responsible for translating incoming data into a syntax that the application layer of the receiving device can understand. If the devices are communicating over an encrypted connection, presentation layer is responsible for adding the encryption on the sender’s end as well as decoding the encryption on the receiver's end so that it can present the application layer with unencrypted, readable data.

Finally, the presentation layer is also responsible for compressing data it receives from the application layer before delivering it to session layer. This helps improve the speed and efficiency of communication by minimizing the amount of data that will be transferred.

Session layer:

The session layer is responsible for managing, opening, and closing communication between the two devices. The session layer ensures that the session stays open long enough to transfer all the data being exchanged, and then promptly closes the session in order to avoid wasting resources. The session layer will also synchronize data transfer with checkpoints. In this case, if a student submits a 100-megabyte file, the session layer could set a checkpoint every 10 megabytes. In the case of a disconnect or a crash after 64 megabytes have been transferred, the session could be resumed from the last checkpoint, meaning only 40 more megabytes of data need to be transferred. Without the checkpoints, the entire transfer would have to begin again from scratch.

 

 

Transport layer:

The transport layer is responsible for end-to-end communication between the two devices. In this case, data from the session layer is broken into chunks called segments before sending it to the network layer. The transport layer on the sender’s end has flow control to determine the optimal speed of transmission, ensuring that when the connection is fast, it doesn’t overwhelm a receiver with a slow connection. The transport layer on the receiving device is responsible for error control by ensuring that the data received is complete. Furthermore, the receiving end also reassembles the segments into data compatible with the session layer.

 

Network layer:

The network layer is responsible for facilitating data transfer between two different networks. The network layer breaks up segments from the transport layer into smaller units, called packets, on the sender’s end, and reassembling these packets on the receiving end. To send data packet from one location to another there should be some way of identifying the exact receiver among all the hosts like sending a postal mail. The network layer on the sender’s side will find the best physical path for the data to reach its destination which is known as routing. It adds the sender IP address and receiver IP address to the data packet. 

Data link layer:

 

 

As the packet moves down the layer net, it reaches the data link layer. The data packet is now ready to be sent via Ethernet. The data packet will be converted into data frames for this purpose. Let's take an example to explain what happens throughout this layer, let say a food delivery man delivering meals to your home. How could the delivery man knows who the package is for, if there are 6 people in the house? However, if you specify the recipient's name, the delivery person will know where it should be delivered. That’s why, the data link layer performs the same function. It specifies the data frame's unique physical address, commonly known as the MAC address. The NIC's MAC address is mostly burnt in. As a result, it can quickly determine which host the packet should be delivered to using this address. This layer will add the sender MAC address as well as the receiver MAC address to the data frame and transmit it over.

Physical layer:

 

The data is now ready to be sent to the receiver. It will prepare data frames in the physical layer. The data frame will be converted to bits in this physical layer. It will be sent across physical media, such as your NIC or wireless connection after it is converted. There isn't much further preparation or action in this layer.

Group Members

1) Mugilan a/l Jayabalan B032010387

2) Ong Pei Kang B032010100

3) Joerizal Bin Pilip B032010310