OSI Upper Layers

The upper OSI layers provide application level support such as the user interface, data formatting, and communication sessions. The upper layers are as follows:

• Application— The layer where applications and users interface with the network. Examples include web browsers, electronic mail, or a word processing program.

• Presentation— The layer that controls format translation and provides data encryption and compression. Examples include ASCII and JPEG.

• Session— The layer responsible for establishing, maintaining, and terminating sessions between presentation layer entities. Protocols that fall at this layer include NetBIOS and RPC.