Application-layer framing

Application-layer framing or application-level framing (ALF) is a method of allowing an application to use its semantics for the design of its network protocols.

This procedure was first proposed by D. D. Clark and David L. Tennenhouse.^[1] It works as follows:

• The application splits the data into useful segments.
  • These segments are called ADUs (application data units).
• The ADUs can be processed in any order.
• The lower layers keep the ADU borders.

This procedure simplifies the quality of service negotiation and provides a simpler method of error checking.

The Real-time Transport Protocol (RTP) is an example of where the semantics of the real-time application are used to segment the data.