A Layered Approach to Networking
Like IBM's SNA, the OSI model was also designed with seven layers:
Please keep in mind that the organization and functions of the OSI layers differed significantly from those of IBM's SNA. The layers were designed so that specific functions (such as ARP) would be contained at specific layers (ARP is a Data Link layer function) and the interface between functions would be specified at the boundaries between layers. All that this really means that an application should not have to know anything about the hardware in order to send or receive data over a network connection and that the hardware shouldn't have to know what application is running in order to send it data from the network.
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