What is the function of the overhead TCM in ODUk?

Question

Options

• AChannel monitoring unlocking
• BPath Trace Identifier Overhead
• CTandem connection monitoring overhead
• DGeneral communication channel overhead

• A
  12% (2)
• B
  6% (1)
• C
  82% (14)

Explanation

TCM stands for Tandem Connection Monitoring, making C the correct answer. In ODUk (the OTN payload/overhead layer defined in ITU-T G.709), TCM overhead enables per-segment performance monitoring and fault management along a multi-operator or multi-domain connection - up to six nested TCM levels (TCM1–TCM6) can be stacked, each covering a different portion of the end-to-end path.

Why the distractors are wrong:

• A ("Channel monitoring unlocking") - Not a defined OTN concept; fabricated phrasing.
• B ("Path Trace Identifier Overhead") - Describes TTI (Trail Trace Identifier), which identifies the endpoints of a connection, not tandem segments.
• D ("General communication channel overhead") - Describes GCC (General Communication Channel, GCC1/GCC2), a separate overhead field used for management-plane communication between network elements.

Memory tip: Think of "tandem" as relay runners handing off a baton - TCM monitors each leg of the handoff between carriers. If you see tandem or segment monitoring in OTN context, the answer is always TCM.

No community discussion yet for this question.