Which three of these are optical channel data unit (ODU) overhead fields? (Choose three)

Question

Options

• Ageneral communication channel 0 (GCC0)
• Bsection monitoring
• Creserved (RES)
• Dgeneral communication channels 1 and 2 (GCC1 GCC2)
• Etandem connection monitoring activation deactivation (TCM ACT)

• A
  9% (3)
• B
  18% (6)
• C
  73% (24)

Explanation

Optical Data Unit (ODU) The ODU overhead is broken into several fields: RES, PM, TCMi, TCM ACT, FTFL, EXP, GCC1/GCC2 and APS/PCC. The reserved (RES) bytes are undefined and are set aside for future The path monitoring (PM) field is similar to the SM field described above. It contains the TTI, BIP- 8, BEI, BDI and Status (STAT) sub-fields. There are six tandem connection monitoring (TCMi) fields that define the ODU TCM sub-layer, each containing TTI, BIP-8, BEI/BIAE, BDI and STAT sub-fields associated to each TCM level (i=1 to 6). The STAT sub-field is used in the PM and TCMi fields to provide an indication of the presence or absence of maintenance signals. The tandem connection monitoring activation/deactivation (TCM ACT) field is currently undefined in the standards. The fault type and fault location reporting communication channel (FTFL) field is used to create a message spread over a 256-byte multiframe. It provides the ability to send forward and backward path-level fault indications. The experimental (EXP) field is a field that is not subject to standards and is available for network operator applications. General communication channels 1 and 2 (GCC1/GCC2) fields are very similar to the GCC0 field except that each channel is available in the ODU. The automatic protection switching and protection communication channel (APS/PCC) supports up to eight levels of nested APS/PCC signals, which are associated to a dedicated-connection monitoring level depending on the value of the multiframe.

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