This Recommendation defines a generic framing procedure (GFP) to encapsulate variable-length payload of various client signals for subsequent transport over SDH, PDH and 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.