The application layer is closest to the end user. It is the layer that provides the interface between the applications used to communicate and the underlying network over which messages are transmitted. Application layer protocols are used to exchange data between programs running on the source and destination hosts.
The upper three layers of the OSI model (application, presentation, and session) define functions of the single TCP/IP application layer.
There are many application layer protocols, and new protocols are always being developed. Some of the most widely known application layer protocols include Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Trivial File Transfer Protocol (TFTP), Internet Message Access Protocol (IMAP), and Domain Name System (DNS) protocol.
TCP/IP Application Layer Protocols
The TCP/IP application protocols specify the format and control information necessary for many common Internet communication functions. Click each application protocol in the figure to learn more about them.
Application layer protocols are used by both the source and destination devices during a communication session. For the communications to be successful the application layer protocols implemented on the source and destination host must be compatible.
Published on Tue 18 May 2010 by Sean Driscoll in Networking with tag(s): application layer