Result: standard mapping
How many STM-64s are in an OTU3?
An OTU3 carries 4 STM-64s, per ITU-T G.709. This is a client mapping of STM-64 into ODU2.
4
STM-64s in an OTU3
Working
OTU3 → 1 × ODU3 → 4 × ODU2 → 1 × STM-64
- 1 × ODU3 in each OTU3 ITU-T G.709The OTU3 frame carries exactly one ODU3.
- 4 × ODU2 in each ODU3 ITU-T G.709Four ODU2s fill the 32 tributary slots of 1.25 Gbit/s.
- 1 × STM-64 in each ODU2 ITU-T G.709Client mappingCBR STM-64 mapped into OPU2.
- 1 ODU3
- 1 × 4 = 4 ODU2s
- 1 × 4 × 1 = 4 STM-64s
Leftover capacity
3.205293559 Gbit/s of each OTU3 line rate (43.018413559 Gbit/s) sits outside 4 × 9.953280 Gbit/s of STM-64 line rate (39.813120 Gbit/s). That remainder is overhead, fixed stuff or justification. It is not another whole tributary.