Open Systems Interconnect Model

Defines Internet function through a vertical stack of seven layers. The uppermost layers represent the implementation of network services such as encryption and connection management, and the lowermost layers implement the hardware-oriented functions such as addressing, flow control, and routing.

Data communication begins with the top layer at the sending side, descends the OSI model stack to the bottom layer, crosses the network connection to the bottom layer on the receiving side, and ascends the OSI model stack.

The OSI model was developed in 1984 to be an abstract model, but it has become a practical framework for developing current network technologies such as Ethernet and protocols such as IP.

See Also: Encapsulation; Encryption or Encipher; Ethernet; Internet; Internet Protocol; Layers; Network.