The OSI Model Layers   

7

Application

Provides services and utilities that enable application programs to access a network and its resources.

  

6

Presentation

Translates data so that it can be moved on the network.

  

5

Session

Establishes a connection between network devices, maintaining that connection, and then terminating it when appropriate

  

4

Transport

Ensures reliable data transmission by breaking up big data blocks into smaller packets that can be sent more efficiently on on the network.

  

3

Network

Addresses and delivers packets across a network.

 L3 Switch, Router

2

Data Link

Ensures frames get from one device to another without error.
After sending frames, the waits for ack. Hardware address.

 Bridge, Switch,

1

Physical

Moves bits of data on and off the physical cabling media.

 hub, repeater, NIC, MAU

Brief Overview:
The OSI networking model is divided into 7 layers. Each layer has a different responsibility, and all the layers work together to provide network data communication.

The Application layer represents user applications, such as software for file transfers, for database access, and for e-mail. It handles general network access, flow control, and error recovery.

The Presentation layer determines data exchange formats and translates specific files from the Application layer format into a commonly recognized data format. It provides protocol conversion, data translation, encryption, character-set conversion, and graphics-command expansion.

The Session layer handles security and name recognition to enable two applications on different computers to communicate over the network.

The Transport layer provides flow control, error handling, and is involved in correction of transmission/reception problems. It also breaks up large data files into smaller packets, combines small packets into larger ones for transmission, and reassembles incoming packets into the original sequence.

The Network layer addresses messages and translates logical addresses and names into physical addresses. It also manages data traffic and congestion involved in packet switching and routing.

The Data Link layer is the interface between the upper "software" layers and the lower "hardware" Physical layer. One of its main tasks is to create and interpret different frame types based on the network type in use. The Data Link layer is divided into two sub-layers: the Media Access Control (MAC) sub-layer and the Logical Link Control (LLC) sub-layer.

The Physical layer is the specification for the actual hardware connection, the electronics, logic circuitry, and wiring that transmit the actual signal.  MEDIA