What is an OSI Model?
If you have been in the tech field for some time, chances are that you have come across the term OSI Model or have heard someone mention the term. If you haven't well you are still in the right place for a simplified answer😊.
To begin with, the OSI Model stands for Open Systems Interconnection Reference Model. It's a framework that's used to understand how different parts of a computer network communicate with each other.
The model itself is divided into 7 layers, each having specific functions to ensure that data can be transmitted smoothly across a network.
1. Physical Layer (Layer 1)
This layer is not about protocols, it's about the signaling, cabling, and connectors. It's more of dealing with physical problems like:
- Fixing the cables, punch-downs, etc...
- Running loopback tests, replacing cables, swapping adapters, etc...
2. Data Link Layer (Layer 2)
Also referred to as the Data Link Control protocol or the Switching layer. It focuses on creating reliable links between directly connected devices. Its main tasks involve:
- handling data framing
- error detection and correction to ensure that data sent from one device is delivered accurately.
3. Network Layer (Layer 3)
Also known as the routing layer. It's the layer associated with IP addresses. It's responsible for routing data over the network. It determines the best path for data to travel from the source to the destination across multiple devices and networks.
4. Transport Layer (Layer 4)
Sometimes also referred to as the post office layer as it describes how data is being delivered and where it is being delivered. Some of its protocols include TCP and UDP. In addition to this it also
- manages data flow,
- provides error checking, and
- reassembles data packets in the correct order if they arrive out of sequence.
5. Session Layer (Layer 5)
Designed to establish, maintain, and terminate connections between one device and another.
6. Presentation Layer (Layer 6)
Mainly used for character encoding and application encryption to be easily understood by the receiving device. It's mostly combined with layer 7. It handles tasks like data compression, encryption, and formatting conversions.
7. Application Layer (Layer 7)
This is the layer that we as humans get to see and interact with. It includes protocols and interfaces used by software applications to exchange information over the network, such as web browsers, email clients, and file transfer programs.
Throughout your career, you will from time to time refer to this model, and understanding it might be challenging but by using the mnemonic All People Seem To Need Data Processing, you can easily recall the entire OSI Model structure.
For a more elaborate guide check this video by Professor Messer.
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