Interconnection between LW40 and LU40 (40G OTU boards)

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The UFEC modules in the LW40 and LU40 boards are provided by different vendors. As a result, the UFEC algorithms of the two boards are different and therefore the two boards cannot be interconnected.
To implement interconnection between LW40 and LU40 boards, disable the UFEC function of the two boards and enable the standard FEC function of the OTN equipment. The FEC error correction capability, however, will be greatly reduced when the standard FEC function of OTN equipment is used.

Other related questions:
Whether the OTU boards LW40 and LU40 in the BWS 1600G single-wavelength 40G system can be interconnected
Question: Can the OTU boards LW40 and LU40 in the BWS 1600G single-wavelength 40G system be interconnected? Root cause: None Answer: The LW40 and LU40 boards cannot be interconnected. The two types of boards use different UFEC algorithms because the chip vendors of the UFEC modules on the LW40 and LU40 boards are different. If the LW40 and LU40 boards need to be interconnected, you must disable the UFEC function on the boards and enable the OTN-based FEC function, but the FEC capability will be degraded.

Differences in dispersion compensation between 40G coherent boards and 40G non-coherent boards
40G non-coherent boards use the TDC technology and the dispersion tolerance is 800 ps/nm. 40G coherent boards use the DSP technology and the dispersion tolerance reaches 60,000 ps/nm. A network deploying non-coherent boards must use DCMs for dispersion compensation. A network that uses only coherent boards does not need to use DCMs.

Whether a board with FEC disabled can be interconnected with an OTU board that does not support FEC
Question: When the 73TRC board with FEC disabled is interconnected with the TWC board, the R_LOF alarm is reported at the receive end and services are unavailable, and even the R_LOS alarm is reported in some cases. Answer: 1. Functioning as a regeneration board of 73LWC, 73TRC also has the FEC function and has the same rate (2.66G) as 73LWC. After the FEC function is disabled on a board, FEC will not be performed at the receive end of the board; the signals transmitted at the transmit end, however, still contain FEC code. In other words, the board rate remains 2.66G. 2. You can use any of the following three methods to disable the FEC function of a board: Use the following command (applicable to NEs on the 5.0 platform): :cfg-set-fec: bid, port, path, enable/disable Use S3 DIP switches. S3.1 specifies the board type. 0: LWC 1: TRC S3.2 specifies whether FEC is configured. 0: with FEC 1: without FEC Use the :ptp,bid,f1,0; command. (The last byte 0 indicates that FEC is configured but 1 indicates that FEC is not configured.) For the 72LWC board, you can use only the PTP command because the board does not have S3 DIP switches. Use the :ptp:bid,b4,1; command. (The last byte 0 indicates that FEC is not configured but 1 indicates that FEC is configured.) Note: The meaning of the last byte in the command for the 71LWC board is opposite to that for the 72LWC board. The FEC setting and cancellation commands for the 71TRC board are the same as those for the 71LWC board, but the parameters are different. Command for setting the FEC mode: Ptp:slot ID,f1,2 (like S3.2 DIP switch setting to 0) Command for canceling the FEC mode: Ptp:slot ID,f1,3 (like S3.2 DIP switch setting to 1) 3. The regeneration boards as follows: The regeneration board of the TWC board is TWC, at a rate of 2.48G. The regeneration board of the 71LWC board is 71TRC, at a rate of 2.66G. The regeneration board of the 72LWC board is 72TRC, at a rate of 2.66G. The regeneration board of the 73LWC board is 73TRC, at a rate of 2.66G. Suggestion and conclusion: Assume that site A and site B are interconnected using an LWC board separately. LWC (A) ----- LWC (B) If you disable the FEC function of the LWC board at site A, the signals transmitted at the WDM side of the LWC board at site A remain unchanged, and the signal structure is still marked with FEC redundancy code and the rate is still 2.66G. However, the receive end on the WDM side of the LWC board at site A does not perform error correction. In this case, if the signals received by site A from site B contain bit errors, site A still transparently transmits the signals containing bit errors to the downstream site. Disabling the FEC function aims at testing the FEC coding gain of the board, rather than interconnecting with the boards that do not have the FEC function. The rate of 2.5G boards without the FEC function is 2.48G, whereas the rate of 2.5G boards with the FEC function is 2.66G. Therefore, the boards cannot be interconnected. Note that the FEC enabling status must be restored after the test.

Service interconnection between TOA and TOG boards
Services on the TOA board can be interconnected with those on the TOG board.

Optical ports of the OTU board
The OTU board provides two groups of optical ports: IN/OUT and Rx/Tx. The IN and OUT ports correspond to WDM-side input and output, and the Rx and Tx ports correspond to SDH-side input and output. The WDM side is also called the line side; the SDH side is also called the client side. In the alarm parameters, 1 indicates the WDM-side transceiver optical port, and 2 indicates the SDH-side transceiver optical port. In some documents, the optical ports of the OTU board are classified into system-side and line-side ports. In the early period, the system side is also called the client side.

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