OSI Layer Model

OSI Model 💬

The OSI model is a layered framework for the design of network systems that allows communication between all types of computer systems. It consists of seven separate but related layers, each of which defines a part of the process of moving information across a network.

Layer 7: Application Layer

According to the project scenario, we know that data travels from the lecturer’s computer to reach the OnlineLearning System server which is in the Cobham College IT Center. Like the first, the process will start with the application layer. By using network applications, such as web browsers, it provides an application layer protocol to receive and send the data. These applications generate data that must be transferred via the network. The data format will be specified by the application layer, and the data will be sent to the presentation layer. In this layer, it provides user interfaces and support for services.

Layer 6: Presentation Layer

In this layer, the data from the application layer is retrieved and processed here so that it may be transmitted across the network in the required format. Another process that will happen in this layer is:

Process	Function
Translation	Before being transferred, the running applications must be converted to bitstreams.
Data encryption / Decryption	- A system must be able to protect privacy when transporting sensitive data. - Encryption refers to the process by which the sender converts the original data into a different format and then delivers the resultant message across the network. - Decryption reverses the encryption process, restoring the communication to its original state.
Data compression	Data compression reduces the number of bits contained in the information.

For instance, at the lecturer’s computer, data will be done process translation, data encryption, and data compression. Data compression reduces the number of bits to successfully receive data on the end-user site, this process was important for the transmission of multimedia. At the receiver site which is the online learning System server in the Cobham College IT Center, it takes data from the session layer and implements data translation, decryption, and decompression.

Layer 5: Session Layer

The session layer being the fifth layer in the OSI model performs several different as well as important functions which are needed for establishing as well as maintaining a safe and synchronizing the interaction between communicating systems.

For example, lectures want to send notes or assignments to students by using an online learning system. The server system in the Cobham College IT Center should support or maintain data from the transport layer that data from the lecturer computer.

Layer 4: Transport Layer

The transport layer defines services to segment transfer, and reassemble the data for individual communications between the end devices. It describes general services and functions that provide ordered and reliable delivery of data between source and destination hosts and implements TCP and UDP protocols.

During the stage, the transport layer provides multiplexing enables the host to send and receive error-corrected data through the implementation of TCP and UDP protocols. The flow and error control will be performed, and the data will be segmented then broken up into packets at the network layer.

Layer 3: Network Layer

The network layer controls the operation of the subnet. The main aim of this layer is to deliver packets from source to destination across multiple links (networks). If two computers(system) are connected on the same link, then there is no need for a network layer. It routes the signal through different channels to the other end and acts as a network controller. It also divides the outgoing messages into packets and assembles incoming packets into messages for higher levels. In broadcast networks, the routing problem is simple. sp the network layer is often thin or even non-existent.

Functions of Network Layer

1. It translates a logical network address into a physical address. Concerned with a circuit, message, or packet switching.

2. Routers and gateways operate in the network layer. The mechanism is provided by the network layer for routing the packets to their final destination.

3. Connection services are provided including network layer flow control network layer error control and packet sequence control.

4. Breaks larger packets into small packets.

Layer 2: Data Link Layer

The data link layer ensures that all packets of information are passed on free of errors. It makes sure the appropriate physical protocol is assigned to the data. The data link layer is the second layer in the OSI Model.

The three main functions of the data link are to deal with transmission errors, regulate the flow of data, and provide a well-defined interface to the network layer. When it transfers the data to the network layer, it uses timers and sequence numbers to check for errors to ensure that all data is successfully received. The data link layer has different services and protocols to complete its tasks. The protocols are the rules required to pass data successfully to the nest layer.

Layer 1: Physical Layer

The Physical Layer, which is a physical and electrical representation of the system, is the lowest layer in the Open System Interconnection (OSI) Model. It is made up of various network components such as power plugs, connectors, receivers, and different cable kinds. The Physical Layer transports data bits from one device (such as a computer) to another (s). The types of encoding (how the 0s and 1s in a signal are encoded) are defined by the Physical Layer. The Physical Layer is in charge of transmitting unstructured raw data streams across a physical channel.