Whether LMP uses OTN overheads or DCC overheads


LMP stands for Link Management Protocol. For optical-layer ASON services, LMP uses the DCC bytes of the OSC channels. For electrical-layer ASON services, LMP uses OTN overheads.

Other related questions:
OTN overheads
The OTN optical-layer overheads include OTS, OMS, and OCh overheads and are transmitted through the OSC. OTN electrical-layer overheads include OPUk, ODUk, OTUk overheads, and the frame alignment overheads.

Monitoring sections of PM and TCM overheads in OTN overheads
The SM, PM, and TCM overheads are generated at the source node and terminated at the sink node. The corresponding boards at the source and sink nodes monitor the signals and report the performance of the signals. The SM overheads need to be terminated and then regenerated at all the nodes that have the 3R functions. That is, all the boards that support the OTN interface must process the SM overheads. The PM overheads are terminated at the sink node of a channel. The TCM overheads can be terminated at a selective sink node based on the actual situation. The TCM overheads have six levels and three allocation modes (cascaded, nested, or overlapped), which can be determined flexibly as required.

Difference between the operation mode and transparent mode in processing overheads
The operation mode and transparent mode differ in the generation of TCM overheads. To be specific, TCM overheads are re-generated in operation mode but not re-generated in transparent mode.

Whether the DCC channels of an SDH device can be disabled through OTU boards on an OTN device
GCC channels on OTU boards in OptiX OSN 6800 are electrical supervisory channels. The enable status of GCC channels does not adversely affect DCC byte transmission on an SDH NE.

Reason why the recommended usage status of ASON overhead bytes is set to "Disabled" for tributary boards when electrical-layer ASON features are enabled on an ASON network
For electrical-layer ASON, tributary boards cannot transmit ASON management bytes. Therefore, you are advised to set the usage status of ASON overhead bytes to "Disabled" for the tributary boards.

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