Open Systems interconnection (OSI) model
The OSI model was presented by the International Organisation for Standardisation (ISO) for how networks should be structured. Its ultimate goal is to gaurentee safe communication between two hosts that may or may not be on the same network. It has 7 layers each with a different responsibility.
- Physical layer,
- Data Link layer,
- Network layer,
- Transport layer,
- Session layer,
- Presentation layer, and
- Application layer
This separation allows for scalability, molecularity and flexibility to add or remove components. Though comes with some down sides such as
- Some layers’ functionality depends on the information from other layers, which can violate the goal of layer separation.
- One layer may duplicate lower-layer functionalities. For example, the functionality of error recovery can occur in lower layers but also in upper layers as well.
- Some additional overhead that is caused by the abstraction between layers.