Page 1194 - 5G Basics - Core Network Aspects

2 Transport aspects

client bits. For the case of C128 = 949, 16 byte blocks #1, #318 and #635 are carrying stuff bits and the other
16-byte blocks are carrying client bits. The stuff bits are set to zero.

Scrambled 64b/66b blocks of the client signal are mapped into 66-bits of the OPUflex payload area skipping
the 16-byte Stuff blocks under control of the BGMP control mechanism. The 66b blocks are aligned so that
the first bit of the sync header appears in one of the bit positions 1, 3, 5, or 7 of a byte in the OPUflex
payload.

Figure 17-22 – Mapping of the combined FlexE stream into ODUflex
via deterministic stuffing and using GMP encoding
During a signal fail condition of an incoming FlexE signal (e.g., in the case of a loss of input signal or FlexE
local fault condition), this failed incoming FlexE signal and the p-1 other FlexE signals are not mapped into
the payload of the OPUflex. Instead the OPUflex payload is filled with the stuff blocks, 66b blocks that carry
a local fault sequence ordered set (as specified in [FlexE IA]) and the OPU CSF bit is set to "1". The OPUflex
clock is derived from a local clock. The OPUflex payload signal bit rate shall be within the limits specified in
Table 7-3 and the limits for the ODCb defined in [ITU-T G.8251] and no frame phase discontinuity shall be
introduced in this case and when resynchronization on the incoming client signal.

During a signal fail condition of the incoming ODUflex/OPUflex signal (e.g., in the case of an ODUflex-AIS,
ODUflex-LCK, ODUflex-OCI condition) or a CSF condition is present in the OPUflex overhead, a stream of
66b blocks, with each block carrying one local fault sequence ordered sets (as specified in [FlexE IA]) is
generated as a replacement signal for each of the p lost FlexE signals.
NOTE 4 – A FlexE signal local fault sequence ordered set is a 66B control block (sync header = 10) with a block type of
0x4B, an "O" code of 0x00, a value of 0x01 to indicate a "local fault" in lane 3, and all of the other octets (before
scrambling) equal to 0x00.

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