OSI models in computer networks

Last updated on November 13th, 2018

What is the OSI model?

OSI model means Open System Interconnection is a reference model that shows how applications communicate over a network.

A reference model is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computer system while not referring to its underlying internal structure and technology.

It is a seven-layer design with every layer having a specific practicality to perform. Of these seven layers work collaboratively to transmit the info from one person to a different across the world.

OSI Model

OSI Model

  1. Application Layer: This layer interacts with software system applications that implement a human activity element. Application-layer functions usually embrace characteristic communication partners, crucial resource convenience, and synchronizing communication. Once characteristic communication partners, the application layer determines the identity and convenience of communication partners for an application with information to transmit. The foremost vital distinction within the application layer is that the distinction between the application-entity and therefore the application.
  2. Presentation Layer: It establishes context between application-layer entities, during which the application-layer entities could use totally different syntax and linguistics if the presentation service provides a mapping between them. If a mapping is offered, presentation protocol knowledge units are encapsulated into session protocol knowledge units and passed down the protocol stack.
  3. Session Layer: Session layer sets up, terminates and coordinates conversations. It services embrace authentication and reconnection once a disruption. On the net, Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) offer these services for many applications.
  4.  Transportation Layer: This Layer is the heart of OSI. It manages packetization of information, then the delivery of the packets, as well as checking for errors within the information once it arrives. On the web, TCP and UDP give these services for many applications likewise.
  5. Network Layer: Network layer provides shift and routing technologies, making logical ways, referred to as virtual circuits, for transmission knowledge from node to node. Routing and forwarding are functions of this layer, also as addressing, internetworking, error handling, congestion management, and packet sequencing.
  6.  Data Link Layer: The data link layer provides node-to-node data transfer—a link between 2 directly connected nodes. It detects and probably corrects errors which will occur within the physical layer. It defines the protocol to determine and terminate an association between 2 physically connected devices. It conjointly defines the protocol for flow management between them.
  7. Physical Layer: Physical layer conveys the bit stream – electrical impulse, light or radio wave — through the network at the mechanical and electrical level. It provides the hardware suggests that of causing and receiving information on a carrier, as well as shaping cables, cards and physical aspects.

Difference between the OSI model and the TCP/IP model:

OSI Model TCP/IP Model
OSI means Open System Interconnection. TCP/IP means Transmission Control Protocol and Internet Protocol.
It has seven layers. It has four layers.
It follows a vertical approach. It follows a horizontal approach.
It developed model then protocols. It developed protocols then model.
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