Optical transport network frame structure with in-band data channel and forward error correction
View Patent ↗An optical transport network data frame structure is configured to provide an in-band data channel. The in-band channel data is contained in the data frame space that would otherwise be allocated to forward error correction (“FEC”) bytes. Consequently, the provision of the in-band data channel does not affect the number of client data bytes contained in the data frame structure. In accordance with a practical embodiment, the data frame structure is compliant with Intra Domain Interface (IaDI) specifications set forth in International Telecommunication Union Telecommunication Standardization Sector (ITU-T) Recommendation Guide For Recommendation, G.709/Y.1331.
1. An optical transport network data frame structure comprising:
a fixed number of client data bytes in a data frame; and
a fixed number of non-client data bytes in the data frame, the fixed number of non-client data bytes comprising a number of in-band channel data bytes and a quantity of forward error correction (“FEC”) parity bytes, the combination of said number of in-band channel data bytes and said quantity of FEC parity bytes occupying a fixed space in the data frame allocated for FEC parity bytes.
2. A data frame structure according to claim 1 , wherein said non-client data bytes comprise a fixed number of overhead bytes.
3. A data frame structure according to claim 1 , wherein a fixed quantity of said FEC parity bytes and a fixed quantity of said in-band channel data bytes fully occupy said fixed data frame space.
4. A data frame structure according to claim 1 , wherein said fixed number of client data bytes, said number of in-band channel data bytes, and said quantity of FEC parity bytes are arranged in N rows.
5. A data frame structure according to claim 4 , wherein N=4.
6. A data frame structure according to claim 5 , wherein each of said N rows contains 4,080 bytes.
7. A data frame structure according to claim 6 , wherein each of said N rows contains 16 overhead bytes.
8. A data frame structure according to claim 7 , wherein each of said N rows contains 3,808 client data bytes.
9. A data frame structure according to claim 8 , wherein said data frame structure is compliant with Intra Domain Interface (“IaDI”) specifications set forth in ITU-T Recommendation G.709/Y.1331.
10. A data frame structure according to claim 4 , wherein:
each of said N rows contains 32D in-band channel data bytes, 32T FEC parity bytes, and 16[254−2(D+T)] client data bytes; and
D and T are integers.
11. A data frame structure according to claim 10 , wherein the sum of D and T is at least eight and no greater than twenty-five.
12. A data frame structure according to claim 10 , wherein the value of T corresponds to a magnitude of FEC applied to said fixed number of client data bytes, to said number of in-band channel data bytes, and to said quantity of FEC parity bytes.
13. A data frame structure according to claim 4 , wherein each of said N rows comprises a plurality of interleaved codewords.
14. A data frame structure according to claim 13 , wherein each of said N rows consists of 16 interleaved Reed-Solomon codewords, each having a length of 255 bytes.
15. A method of formatting an optical transport network data frame structure, said method comprising:
obtaining client data bytes and in-band channel data bytes;
framing said client data bytes into a client data payload section of a data frame structure, said client data payload section having a fixed byte capacity;
inserting said in-band channel data bytes into a first portion of a fixed forward error correction/forward error correction data channel (“FEC/FDC”) data frame space of said data frame structure, said FEC/FDC data frame space having a fixed byte capacity allocated for forward error correction (“FEC”); and
adding a quantity of FEC parity bytes into a second portion of said FEC/FDC data frame space.
16. A method according to claim 15 , further comprising:
allocating a first fixed byte capacity of said FEC/FDC data frame space for said in-band channel data bytes; and
allocating a second fixed byte capacity of said FEC/FDC data frame space for said quantity of FEC parity bytes.
17. A method according to claim 16 , wherein allocating said second fixed byte capacity is responsive to performance characteristics of a data communication network that supports said data frame structure.
18. A method according to claim 16 , wherein said in-band channel data bytes and said quantity of FEC parity bytes fully occupy said FEC/FDC data frame space.
19. A method according to claim 15 , wherein:
said framing step arranges said client data bytes into N rows;
said inserting step arranges said in-band channel data bytes into said N rows; and
said adding step arranges said FEC parity bytes into said N rows.
20. A method according to claim 19 , wherein:
N=4; and
each of said N rows contains 4,080 bytes.
21. A method according to claim 20 , wherein:
each of said N rows contains 3,808 client data bytes; and
each of said N rows contains 256 bytes allocated to said FEC/FDC data frame space.
22. A data communication apparatus comprising:
a framer having a client data input for receiving client data and an in-band channel data input for receiving in-band channel data, said framer being configured to frame client data bytes representing said client data and in-band channel data bytes representing said in-band channel data into a data frame structure;
said data frame structure comprising a client data payload section having a fixed byte capacity for said client data bytes, and a fixed forward error correction/forward error correction data channel (“FEC/FDC”) data frame space having a fixed byte capacity allocated for forward error correction (“FEC”) that accommodates said in-band channel data bytes; and
a FEC encoder coupled to said framer, said FEC encoder being configured to receive partially filled data frame structures from said framer and to add a quantity of FEC parity bytes into said fixed FEC/FDC data frame space.
23. A data communication apparatus according to claim 22 , wherein:
said framer includes an overhead data input for receiving overhead data; and
said framer is further configured to frame overhead data bytes representing said overhead data into a fixed overhead data frame space of said data frame structure.
24. A data communication apparatus according to claim 22 , wherein said framer is further configured to allocate said fixed FEC/FDC data frame space between a first portion reserved for said in-band channel data bytes and a second portion reserved for said quantity of FEC parity bytes.
25. A data communication apparatus according to claim 24 , wherein said FEC encoder is further configured to add said quantity of FEC parity bytes to said second portion of said fixed FEC/FDC data frame space.
26. A data communication apparatus according to claim 22 , wherein:
said data frame structure consists of four rows, each containing 32D in-band channel data bytes, 32T FEC parity bytes, and 16[254−2(D+T)] client data bytes; and
D and Tare integers.
27. A data communication apparatus according to claim 26 , wherein the sum of D and T is at least eight and no greater than twenty-five.
28. A data communication method comprising:
receiving a data frame structure comprising a client data payload section having a fixed byte capacity for a number of client data bytes, and a fixed forward error correction/forward error correction data channel (“FEC/FDC”) data frame space having a fixed byte capacity allocated for forward error correction (“FEC”) that accommodates a number of in-band channel data bytes and a quantity of FEC parity bytes;
performing FEC on said data frame structure in response to said quantity of FEC parity bytes; and
extracting said number of client data bytes and said number of in-band data channel bytes from said data frame structure.
29. A method according to claim 28 , further comprising identifying said quantity of FEC parity bytes in said FEC/FDC data frame space.
30. A method according to claim 28 , wherein said extracting step separates said number of client data bytes from said number of in-band data channel bytes.
31. A method according to claim 28 , wherein said number of in-band channel data bytes and said quantity of FEC parity bytes fully occupy said FEC/FDC data frame space.
32. A method according to claim 28 , wherein:
said data frame structure consists of four rows, each containing 32D in-band channel data bytes, 32T FEC parity bytes, and 16[254−2(D+T)] client data bytes; and
D and T are integers.
33. A method according to claim 32 , wherein the sum of D and T is at least eight and no greater than twenty-five.
34. A data communication apparatus comprising:
a forward error correction (“FEC”) decoder configured to receive a data frame structure comprising a client data payload section having a fixed byte capacity for a number of client data bytes, and a fixed forward error correction/forward error correction data channel (“FEC/FDC”) data frame space having a fixed byte capacity allocated for FEC that accommodates a number of in-band channel data bytes and a quantity of FEC parity bytes, said FEC decoder being configured to perform FEC on said data frame structure in response to said quantity of FEC parity bytes; and
a deframer coupled to said FEC decoder, said deframer being configured to extract said number of client data bytes and said number of in-band data channel bytes from said data frame structure.
35. A data communication apparatus according to claim 34 , wherein said FEC decoder is further configured to identify said quantity of FEC parity bytes in said FEC/FDC data frame space.
36. A data communication apparatus according to claim 34 , wherein said in-band channel data bytes and said quantity of FEC parity bytes fully occupy said FEC/FDC data frame space.
37. A data communication apparatus according to claim 34 , wherein:
said data frame structure consists of four rows, each containing 32D in-band channel data bytes, 32T FEC parity bytes, and 16[254−2(D+T)] client data bytes; and
D and T are integers.
38. A method according to claim 37 , wherein the sum of D and T is at least eight and no greater than twenty-five.
39. A data communication method comprising:
receiving a data frame structure comprising a client data payload section having a fixed byte capacity for a number of client data bytes, and a fixed forward error correction/forward error correction data channel (“FEC/FDC”) data frame space having a fixed byte capacity allocated for forward error correction (“FEC”) that accommodates a first set of in-band channel data bytes and a first set of FEC parity bytes;
performing FEC on said data frame structure in response to said first set of FEC parity bytes; and
changing the contents of said fixed FEC/FDC data frame space from said first set of in-band channel data bytes to a second set of in-band channel data bytes.
40. A method according to claim 39 , further comprising replacing said first set of FEC parity bytes in said fixed FEC/FDC data frame space with a second set of FEC parity bytes.
41. A method according to claim 40 , wherein:
said first set of FEC parity bytes corresponds to a FEC process having a first magnitude; and
said second set of FEC parity bytes corresponds to a FEC process having a second magnitude.
42. A method according to claim 39 , wherein said changing step comprises extracting a portion of said first set of in-band channel data bytes.
43. A method according to claim 42 , wherein said changing step further comprises adding new in-band channel data bytes to said fixed FEC/FDC data frame space.
44. A method according to claim 39 , wherein said changing step comprises adding new in-band channel data bytes to said fixed FEC/FDC data frame space.
45. An optical transport network data frame structure comprising:
four rows of data, each having a total of 4,080 eight-bit bytes;
a forward error correction/forward error correction data channel (“FEC/FDC”) data frame space having a fixed byte capacity allocated for forward error correction (“FEC”) that accommodates in-band channel data bytes and FEC parity bytes;
each row of data having 16 overhead bytes, 3,808 client data bytes, and 256 bytes allocated to said FEC/FDC data frame space; and
said data frame structure being compliant with Intra Domain Interface (“IaDI”) specifications set forth in ITU-T Recommendation G.709/Y.1331.
46. A data frame structure according to claim 45 , wherein:
said 256 bytes allocated to said FEC/FDC data frame space consists of 32D in-band channel data bytes and 32T FEC parity bytes; and
D and T are integers.
47. A data frame structure according to claim 45 , wherein each of said rows consists of 16 interleaved Reed-Solomon codewords, each having a length of 255 bytes.