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

This procedure was first proposed by D. D. Clark and D. 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 among others the quality of service negotiation and allows a simpler way of error checking.

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