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. It works as follows:
The application splits the data into useful segments.
These segments are called ADUs (application data units).
The Real-time Transport Protocol (RTP) is an example of where the semantics of the real-time application are used to segment the data.
References
↑Clark, D. D. and Tennenhouse, D. L. (1990). Architectural considerations for a new generation of protocols. In: ACM SIGCOMM Computer Communication Review archive
Volume 20, Issue 4 (September 1990),
Pages 200 - 208,
ISSN 0146-4833.