What is the OSI Model

The OSI pattern is a indite possibility which most IT professionals use to describe networks and material applications. The OSI assistant was originally deliberate to account a realized set of creation cloth protocols, but the outgo and complexity of the governing processes entangled in process the OSI mesh made the externalize enviable. In the case that the OSI designers spent arguing over who would be accountable for what, Protocol conquered the reality.

The seven layers of the OSI model are:

7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical


Application Layer:
The Application Layer of the OSI model is responsible for providing end-user services, Like file transfers, electronic messaging, e-mail, virtual terminal access, and network management. This is the layer with which the user interacts.

Presentation Layer:

The Presentation Layer of the OSI model is responsible for defining the structure which two network hosts use to communicate. Encryption and compression should be Presentation Layer functions.

Session Layer:

The Session Layer of the OSI model is responsible for establishing process-to-process communications between networked hosts.

Transport Layer:

The Transport Layer of the OSI model is responsible for delivering messages between networked hosts. The Transport Layer should be responsible for fragmentation and reassembly.

Network Layer:

The Network Layer of the OSI model is responsible for establishing paths for data transfer through the network. Routers operate at the Network Layer.

Data Link Layer:

The Data Link Layer of the OSI model is responsible for communications between adjacent network nodes. Hubs and switches operate at the Data Link Layer.

Physical Layer:

The Physical Layer of the OSI model is responsible for bit-level transmission between network nodes. The Physical Layer defines items such as: connector types, cable types, voltages, and pin-outs.