Page 1150 - 5G Basics - Core Network Aspects

2 Transport aspects

Figure 15-20  ODU PM BIP-8 computation

15.8.2.1.3 ODU PM backward defect indication (BDI)

For path monitoring, a single-bit backward defect indication (BDI) signal is defined to convey the signal fail
status detected in a path termination sink function in the upstream direction.

BDI is set to "1" to indicate an ODU backward defect indication, otherwise it is set to "0".
The ODUk and ODUCn contain one instance of ODU PM BDI overhead.

15.8.2.1.4 ODU PM backward error indication (BEI)
For path monitoring, a four-bit backward error indication (BEI) signal is defined to convey in the upstream
direction the count of interleaved-bit blocks that have been detected in error by the corresponding ODU
path monitoring sink using the BIP-8 code. This count has nine legal values, namely 0-8 errors. The
remaining seven possible values represented by these four bits can only result from some unrelated
condition and shall be interpreted as zero errors (see Table 15-2).
The ODUk contains one instance of ODU PM BEI overhead. The ODUCn contains n instances of the ODU PM
BEI overhead, numbered 1 to n (BEI #1 to BEI #n).

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