Method and apparatus for transporting client signal in optical transport network

A method for receiving a client signal in an optical transport network (OTN), comprising:

• parsing an optical channel payload unit-k (OPUk) of an OTN frame to acquire a second area in an OPUk overhead field;
• if it is determined that values of a first series of bit positions in the second area of the OTN frame are reversed relative to values of the first series of bit positions of the previous OTN frame, according to a increased Cn value, restoring data of the OPUk payload area of a next OTN frame to acquire a client signal data stream;
• and
• if it is determined that values of a second series of bit positions in the second area of the OTN frame are reversed relative to values of the second series of bit positions of the previous OTN frame, according to a decreased Cn value, restoring data of the OPUk payload area of the next OTN frame to acquire the client signal data stream.

An apparatus for transmitting a client signal in an optical transport network (OTN), comprising:

• an acquiring unit configured to acquire the client signal, and extract a client signal clock from the client signal;
• a client signal byte number Cn generating unit configured to generate a client signal byte number Cn transported in an OTN frame period according to the client signal clock and a system clock;
• a first processing unit configured to reverse, if the Cn transported in the OTN frame needs to be increased, values of a first series of bit positions of a second area in an optical channel payload unit-k (OPUk) of the OTN frame, and fill values of a second series of bit positions of the second area in the OPUk with a Cn filled in a previous OTN frame;
• and
• a second processing unit configured to reverse, if the Cn transported in the OTN frame needs to be decreased, values of a second series of bit positions of the second area in the OPUk overhead field of the OTN frame, and fill values of the first series of bit positions of the second area in the OPUk with the Cn filled in the previous OTN frame.

An apparatus for receiving a client signal in an optical transport network (OTN), comprising:

• a parsing unit configured to parse an optical channel payload unit-k (OPUk) of an OTN frame to acquire a second area in an OPUk overhead field;
• if it is determined that values of a first series of bit positions in the second area of the OTN frame are reversed relative to values of the first series of bit positions of the previous OTN frame, according to a increased Cn value, a restoring unit configured to restore data of the OPUk payload area of a next OTN frame to acquire a client signal data stream;
• and
• if it is determined that values of a second series of bit positions in the second area of the OTN frame are reversed relative to values of the second series of bit positions of the previous OTN frame, according to a decreased Cn value, a restoring unit configured to restore data of the OPUk payload area of the next OTN frame to acquire the client signal data stream.

A method for transmitting a client signal in an optical transport network, OTN, comprising:

• saving an acquired range of a client signal byte number Cn of a client signal transported in one OTN frame period;
• acquiring the client signal, and computing the Cn transported in the OTN frame period according to a client signal clock and a system clock;
• identifying whether the Cn exceeds the range in a first area of a Cbyte field of an optical channel payload unit-k, OPUk, wherein the Cbyte field is divided into the first area and a second area;
• in a current OTN frame, if the computed Cn exceeds the range, filling in a second area of the Cbyte field of the OPUk with the computed Cn;
• and if the computed Cn falls in the range, filling in the second area of the Cbyte field of the OPUk of the current OTN frame with the Cn same as that filled in the previous OTN frame;
• and
• in the frame next to the current OTN frame, mapping Cn client signal bytes to an OPUk payload area, and transmitting an optical channel transport unit, OTU, comprising the OPUk to the OTN network.

A computer readable storage medium, comprising a program, adapted to execute the step:

• saving an acquired range of a client signal byte number Cn of a client signal transported in one OTN frame period;
• acquiring the client signal, and computing the Cn transported in the OTN frame period according to a client signal clock and a system clock;
• identifying whether the Cn exceeds the range in a first area of a Cbyte field of an optical channel payload unit-k, OPU;
• in a current OTN frame, if the computed Cn exceeds the range, filling in a second area of the Cbyte field of the OPUk with the computed Cn;
• and if the computed Cn falls in the range, filling in the second area of the Cbyte field of the OPUk of the current OTN frame with the Cn same as that filled in the previous OTN frame;
• and
• in the frame next to the current OTN frame, mapping Cn client signal bytes to an OPUk payload area, and transmitting an optical channel transport unit, OTU, comprising the OPUk to the OTN network.

A component comprising:

• a processor configured to implement a method for transmitting a client signal in an optical transport network (OTN), comprising:
• acquiring the client signal;
• extracting a client signal clock from the client signal;
• generating a client signal byte number Cn transported in an OTN frame period according to a client signal clock and a system clock;
• if the Cn transported in the OTN frame needs to be increased, reversing, values of a first series of bit positions of a second area in an optical channel payload unit-k (OPUk) of the OTN frame, and filling values of a second series of bit positions of the second area in the OPUk with a Cn filled in a previous OTN frame;
• if the Cn transported in the OTN frame needs to be decreased, reversing, values of the second series of bit positions of the second area in the OPUk overhead field of the OTN frame, and filling values of the first series of bit positions of the second area in the OPUk with the Cn filled in the previous OTN frame.