This document describes the types and bit rates of the OTUk, ODUk, OPUk, OTUCn, ODUCn, and OPUCn signals of

OTN line board supports beyond 100 Gbit/s, 40 Gbit/s, 10 Gbit/s, 2.5 Gbit/s, 1.25 Gbit/s and other line rates.

Note:

- OTUk (k = 1, 2, 3, 4, X5, or X10); ODUk (k = 0, 1, 2, 2e, 3, 4, flex, X5, or X10); OPUk (k = 0, 1, 2, 2e, 3, 4, flex, X5, or X10)
- OTUCn (n = 2 or 4); ODUCn (n = 2 or 4); OPUCn (n = 2 or 4)

##### OTU Types and Bit Rates

`OTUk rate = 255/(239-k) x STM-N bit rate`

OTU Type | OTU Nominal Bit Rate | OTU Bit Rate Tolerance |
---|---|---|

OTU1 | 255/238 × 2 488 320 kbit/s | ±20 ppm |

OTU2 | 255/237 × 9 953 280 kbit/s | ±20 ppm |

OTU3 | 255/236 × 39 813 120 kbit/s | ±20 ppm |

OTU4 | 255/227 × 99 532 800 kbit/s | ±20 ppm |

OTUX5 | 255/227 × 155 520 × 640/2 kbit/s | ±20 ppm |

OTUX10 | 255/227 × 155 520 × 640 kbit/s | ±20 ppm |

OTUCn | n × 239/225 × 99 532 800 kbit/s | ±20 ppm |

Note:

- The nominal OTUk rates are approximately: 2 666 057.143 kbit/s (OTU1), 10 709 225.316 kbit/s (OTU2), 43 018 413.559 kbit/s (OTU3), 55,904,986.784 kbit/s (OTUX5), and 111,809,973.568 kbit/s (OTU4/OTUX10).
- The nominal OTUCn rates are approximately: n × 105 725 952.000 kbit/s.

Note: each OTUk consists of 4080 x 4 bytes. Each OPUk payload consists of 3808 x 4 bytes. The 255/238, 255/237, and 255/236 in the OTUk nominal rates indicate the ratio of post-FEC check bytes to pre-FEC check bytes. The supplementary description is as follows:

- OTU1: The ratio of post-FEC check bytes to pre-FEC check bytes is as follows: (4080 x 4)/(3808 x 4) = 255/238. The OTU1 bit rate is 255/238 times the STM-16 bit rate.
- OTU2: 16 columns of stuffing information are added when STM-64 is mapped to OPU2 as payload. Therefore, the ratio of post-FEC check bytes to pre-FEC check bytes is as follows: (4080 x 4)/[(3808- 16) x 4] = 255/237. The OTU2 bit rate is 255/237 times 4 times the STM-16 bit rate.
- OTU3: 32 columns of stuffing information are added when STM-256 is mapped to OPU3 as payload. Therefore, the ratio of post-FEC check bytes to pre-FEC check bytes is as follows: (4080 x 4)/[(3808- 32) x 4] = 255/236. The OTU3 bit rate is 255/236 times 16 times the STM-16 bit rate.
- OTU4: The OTU4 bit rate is 255/227 times 10 times the STM-64 client bit rate.

##### ODU Types and Bit Rate

`ODUk rate = 239/(239-k) x STM-N bit rate`

ODU Type | ODU Nominal Bit Rate | ODU Bit Rate Tolerance |
---|---|---|

ODU0 | 1 244 160 kbit/s | ±20 ppm |

ODU1 | 239/238 × 2 488 320 kbit/s | ±20 ppm |

ODU2 | 239/237 × 9 953 280 kbit/s | ±20 ppm |

ODU3 | 239/236 × 39 813 120 kbit/s | ±20 ppm |

ODU2e | 239/237 × 10 312 500 kbit/s | ±100 ppm |

ODU4 | 239/227 × 99 532 800 kbit/s | ±20 ppm |

ODUX5 | 239/227 × 49 766 400 kbit/s | ±20 ppm |

ODUX10 | 239/227 × 99 532 800 kbit/s | ±20 ppm |

ODUflex for CBR client signals | 239/238 × client signal bit rate | Client signal bit rate tolerance, with a maximum of ±100 ppm |

ODUflex for GFP-F mapped client signals | 476/3,824 × n × 15,230/15,232 × ODU2 bit rate | ±20 ppm |

ODUCn | n × 239/225 × 99 532 800 kbit/s | ±20 ppm |

Note:

- The nominal ODUk rates are approximately: 2 498 775.126 kbit/s (ODU1), 10 037 273.924 kbit/s (ODU2), 40 319 218.983 kbit/s (ODU3), 10 399 525.316 kbit/s (ODU2e), and 104 794 445.815 kbit/s (ODU4), 52,397,222.907 kbit/s (ODUX5), and 104,794,445.815 kbit/s (ODU4/ODUX10).
- The nominal ODUCn rates are approximately: n × 105 725 952.000 kbit/s.
- The value “n” represents the number of tributary slots occupied by the ODUflex (GFP-F).

Note: each ODUk consists of 3824 x 4 bytes. Each OPUk payload consists of 3808 x 4 bytes. The 239/238, 239/237, and 239/236 in the ODUk nominal rates indicate the ratio of the ODUk bytes to the OPUk payload excluding the stuffing information. The supplementary description is as follows:

- The ODU0 bit rate is 50% of the STM-16 bit rate.
- ODU1: No stuffing information is added when STM-16 is mapped to OPU1 as payload. Therefore, the ratio of the ODU1 bytes to the OPU1 payload is as follows: (3824 x 4)/(3808 x 4) = 239/238. The ODU1 bit rate is 239/238 times the STM-16 bit rate.
- ODU2: 16 columns of stuffing information are added when STM-64 is mapped to OPU2 as payload. Therefore, the ratio of the ODU2 bytes to the OPU2 payload excluding the stuffing information is as follows: (3824 x 4)/[(3808- 16) x 4] = 239/237. The ODU2 bit rate is 239/237 times 4 times the STM-16 bit rate.
- ODU3: 32 columns of stuffing information are added when STM-256 is mapped to OPU3 as payload. Therefore, the ratio of the ODU3 bytes to the OPU3 payload excluding the stuffing information is as follows: (3824 x 4)/[(3808- 32) x 4] = 239/236. The ODU3 bit rate is 239/236 times 16 times the STM-16 bit rate.
- ODU2e: An ODU2e signal is generated using the timing of its client signal. The ODU2e bit rate is 239/237 times the 10GBASE-R client bit rate.
- ODU4: The ODU4 bit rate is 239/227 times 10 times the STM-64 client bit rate.

##### OPU Types and Bit Rates

`OPUk rate = 238/(239-k) x STM-N bit rate`

OPU Type | OPU Payload Nominal Bit Rate | OPU Payload Bit Rate Tolerance |
---|---|---|

OPU0 | 238/239 × 1 244 160 kbit/s | ±20 ppm |

OPU1 | 2 488 320 kbit/s | ±20 ppm |

OPU2 | 238/237 × 9 953 280 kbit/s | ±20 ppm |

OPU3 | 238/236 × 39 813 120 kbit/s | ±20 ppm |

OPU2e | 238/237 × 10 312 500 kbit/s | ±100 ppm |

OPU4 | 238/227 × 99 532 800 kbit/s | ±20 ppm |

OPUX5 | 238/227 × 49 766 400 kbit/s | ±20 ppm |

OPUX10 | 238/227 × 99 532 800 kbit/s | ±20 ppm |

OPUflex for CBR client signals | Client signal bit rate | Equals the client signal bit rate tolerance, maximum value ±100 ppm |

OPUflex for GFP mapped client signals | 238/239 × ODUflex signal bit rate | ±20 ppm |

OPUCn | n × 238/225 × 99 532 800 kbit/s | ±20 ppm |

Note:

The nominal OPUk payload rates are approximately: 1,238,954.310 kbit/s (OPU0), 2,488,320.000 kbit/s (OPU1 payload), 9,995,276.962 kbit/s (OPU2 payload), 10,356,012.658 kbit/s (OPU2e payload), 40 150 519.322 kbit/s (OPU3 payload), 52,177,987.665 kbit/s (OPUX5 payload), and 104,355,975.330 kbit/s (OPU4/OPUX10 payload).

The nominal OPUC2 payload rates are approximately: 210 567 168.000 kbit/s.

Note: Each ODUk consists of 3824 x 4 bytes. Each OPUk payload consists of 3808 x 4 bytes. In the OPU Payload Nominal Bit Rate column, “238/239” indicates the ratio of the OPU0 payload to the ODU0 bytes, and “238/237” indicate the ratio of the OPUk payload to the OPUk payload (excluding the padding information). The following provides a supplementary description:

- OPU0: The ratio of the OPU0 payload to the ODU0 bytes is derived from the following equation: (3808 x 4)/(3824 x 4) = 238/239. The OPU0 bit rate is 238/239 times 50% of the STM-16 client signal bit rate.
- OPU1: No padding information is added when STM-16 is mapped to OPU1 as payload. The OPU1 bit rate is the STM-16 client signal bit rate.
- OPU2: 16 columns of padding information are added when STM-64 is mapped to OPU2 as payload. Therefore, the ratio of the OPU2 payload to the OPU2 payload (excluding the padding information) is derived from the following equation: (3808 x 4)/[(3808 – 16) x 4] = 238/237. The OPU2 bit rate is 238/237 times 4 times the STM-16 client signal bit rate.
- OPU2e: The OPU2e bit rate is 238/237 times the 10GBASE-R client signal bit rate.
- OPU3: The ratio of the OPU3 payload to the OPU3 payload excluding the stuffing information is as follows: (3808 x 4)/[(3808- 32) x 4] = 238/236. The OPU3 bit rate is 238/236 times 16 times the STM-16 bit rate.
- OPU4: The OPU4 bit rate is 238/227 times 10 times STM-64 client bit rate.