OSI Model in Networking in Urdu , Computer Networking tutorial 17 lecture

OSI Model in Networking in Hindi Urdu p1, Computer Networking tutorial 17 lectur.

Developed by representatives of major computer and telecommunication companies beginning in 1983, OSI was originally intended to be a detailed specification of actual interfaces. Instead, the committee decided to establish a common reference model for which others could then develop detailed interfaces, which in turn could become standards. OSI was officially adopted as an international standard by the International Organization of Standards (ISO).

The seven Open Systems Interconnection layers are:

Layer 7: The application layer. 

       This is the layer at which communication partners are identified (Is there someone to talk to?), network capacity is assessed (Will the network let me talk to them right now?), and that creates a thing to send or opens the thing received.  

 Layer 6: The presentation layer. 

        In this layer is usually part of an operating system (OS) and converts incoming and outgoing data from one presentation format to another (for exp, from clear text to encrypted text at one end and back to clear text at the other..

Layer 5: The session layer. 

     This layer sets up, coordinates and terminates conversations. Services include authentication and reconnection after an interruption. On the Internet, Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) provide these services for most applications.

 Layer 4: The transport layer.

       This layer manages packetization of data, then the delivery of the packets, including checking for errors in the data once it arrives. On the Internet, TCP and UDP provide these services for most applications as well.

Layer 3: The network layer.

       This layer handles the addressing and routing of the data (sending it in the right direction to the right destination on outgoing transmissions and receiving incoming transmissions at the packet level). IP is the network layer for the Internet.

Layer 2: The data-link layer.

        This layer sets up links across the physical network, putting packets into network frames. This layer has two sub-layers, the Logical Link Control Layer and the Media Access Control Layer. Ethernet is the main data link layer in use.

Layer 1: The physical layer.

      This layer conveys the bit stream through the network at the electrical, optical or radio level. It provides the hardware means of sending and receiving data on a carrier network.