Generic Framing Procedure (GFP) is a multiplexing technique defined by ITU-T G.7041.
This allows mapping of variable length, higher-layer client signals over a circuit switched transport network like OTN, SDH/SONET or PDH.
The client signals can be protocol data unit (PDU) oriented (like IP/PPP or Ethernet media access control) or can be block-code oriented (like Fibre Channel).
The GFP control frame currently consists only of a core header field with no payload area.
This frame is used to compensate for the gaps between the client signal where the transport medium has a higher capacity than the client signal, and is better known as an idle frame.