This Recommendation defines a generic framing procedure (GFP) to encapsulate variable-length payload of various client signals for subsequent transport over synchronous digital hierarchy (SDH), plesiochronous digital hierarchy (PDH) and optical transport network (OTN) networks as defined in [ITU-T G.707], [ITU-T G.8040] and [ITU-T G.709]. This Recommendation defines the:

– frame formats for protocol data units (PDUs) transferred between GFP initiation and termination points;

– mapping procedure for the client signals into GFP.

The framing procedure described in this Recommendation can be applied to both the encapsulation of entire client frames (frame-mapped GFP), in which a single client frame is mapped into a single GFP frame, and to character-mapped transport (transparent GFP), in which a number of client data characters are mapped into efficient block codes for transport within a GFP frame