Network models

The models are used to describe how data moves around a network. There are two network models: OSI and TCP/IP. The OSI model was created at a time when networks were not widely used. And the TCP/IP is a modern network model. However, the OSI model is still in use by the network guys to describe Network Architecture.

The OSI model consists of 7 layers: 

Physical layer

This is the lower layer of the OSI model. It describes how the data in the form of electrical impulses moves between devices. It includes cables, hubs, network adapters, and modems.

Data Link layer

This is the layer where the data is being structured and evaluated. 64 bits of data in the form of an Ethernet packet are being sent from one MAC address to another. Switches and network cards do the main job here.

Network layer

This layer is responsible for sending data in the form of IP packets from one IP address to another. At this level, routers are the main actors.

Transport layer

The layer controls data structure and size and ensures that all the sent packets are delivered. The best example is the Transmission Control Protocol (TCP).

Session layer

On this layer exists the actual connection established between two systems. It controls the creation of the connection and its termination.

Presentation layer

This is the layer where data is converted into the format that the system or the application can read.

Application layer

Parts of the application that are aware of the network communication. All the communication between the world and the application is processed here.

The modern TCP/IP model is simpler and some layers include more than 1 OSI model layer. It has 4 layers:

Network interface layer

Also known as a Link layer. It includes the data transfer between MAC addresses of the network. The hardware list that works here: cables, hubs, switches, network cards

Internet layer

This layer is responsible for sending data between IPs. Corresponds to the Network layer of the OSI model. The main actor here is a router.

Transport layer

Manages the connection between hosts, controls data chunks delivery. 

Application layer

On this layer, data is converted into the syntax that the application accepts. Also, the network communication software is situated here.

By Eugene Okulik