March 14, 2016
Open System Interconnection or OSI is a standard for computer communications that defines a networking framework for protocols that is set in seven layers. When a computer begins a transmission data is passed from one layer to the next, starting at the application layer in one computer, flowing to the bottom layer being the physical layer, over to the next computer and back up the seven layers. At one time, most vendors created their own standards to get companies to only use their computers in one form or another, because the OSI was too loosely defined so proprietary standards were the norm. Now ...view middle of the document...
This same idea applies for any data which needs to be sent from one computer to another. The OSI model which was created by the IEEE committee is to ensure that everyone follows these guidelines (just like the production line above) and therefore each computer will be able to communicate with every other computer, regardless of whether one computer is a Macintosh and the other is a PC. In the picture below you can see how the headers are added through each layer as in the analogy of the production line.
In the TCP/IP model some of the layers have been condensed into the application layer. Instead of having seven layers there are only four as shown in this figure.
The layers are as follows,
The Application layer provides applications the ability to access the services of the other layers and defines the protocols that applications use to exchange data. The Hypertext Transfer Protocol (HTTP) is used to transfer files that make up the Web pages of the World Wide Web.
The File Transfer Protocol (FTP) is used for interactive file transfer. The following Application layer protocols help facilitate the use and management of TCP/IP networks: The Domain Name System (DNS) is used to resolve a host name to an IP address. The Routing Information Protocol (RIP) is a routing protocol that routers use to exchange routing information on an IP internetwork. Next is the transport Layer, the transport layer is responsible for providing the Application layer with session communication services. The core protocols of the Transport layer are Transmission Control Protocol (TCP). TCP provides a one-to-one, connection-oriented, reliable communications service. TCP is responsible for the establishment of a TCP connection, the sequencing and acknowledgment of packets sent, and the recovery of packets lost during transmission. The Transport layer picks up the responsibilities of the OSI Transport layer and some of the responsibilities of the OSI Session layer. The internet layer is responsible for addressing, packaging, and routing. The Internet...