Result: standard mapping
How many STM-64s are in an OTU4?
An OTU4 carries 10 STM-64s, per ITU-T G.709. This is a client mapping of STM-64 into ODU2.
10
STM-64s in an OTU4
Working
OTU4 → 1 × ODU4 → 10 × ODU2 → 1 × STM-64
- 1 × ODU4 in each OTU4 ITU-T G.709The OTU4 frame carries exactly one ODU4.
- 10 × ODU2 in each ODU4 ITU-T G.709Ten ODU2s use all 80 tributary slots, eight slots each.
- 1 × STM-64 in each ODU2 ITU-T G.709Client mappingCBR STM-64 mapped into OPU2.
- 1 ODU4
- 1 × 10 = 10 ODU2s
- 1 × 10 × 1 = 10 STM-64s
Leftover capacity
12.277173568 Gbit/s of each OTU4 line rate (111.809973568 Gbit/s) sits outside 10 × 9.953280 Gbit/s of STM-64 line rate (99.532800 Gbit/s). That remainder is overhead, fixed stuff or justification. It is not another whole tributary.
By bit rate only
Dividing the line rates gives 11.23, which floors to 11 STM-64s by bit rate only. The standard mapping is 10. Use the mapping.