Result: standard mapping
How many STM-4s are in an OTU2?
An OTU2 carries 16 STM-4s, per ITU-T G.709 and ITU-T G.707. This path maps STM-64 into ODU2 as a client, then follows that client's tributaries.
16
STM-4s in an OTU2
Working
OTU2 → 1 × ODU2 → 1 × STM-64 → 16 × STM-4
- 1 × ODU2 in each OTU2 ITU-T G.709The OTU2 frame carries exactly one ODU2.
- 1 × STM-64 in each ODU2 ITU-T G.709Client mappingCBR STM-64 mapped into OPU2.
- 16 × STM-4 in each STM-64 ITU-T G.70716 × STM-4.
- 1 ODU2
- 1 × 1 = 1 STM-64
- 1 × 1 × 16 = 16 STM-4s
Leftover capacity
755.945316 Mbit/s of each OTU2 line rate (10.709225316 Gbit/s) sits outside 16 × 622.080 Mbit/s of STM-4 line rate (9.953280 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 17.21, which floors to 17 STM-4s by bit rate only. The standard mapping is 16. Use the mapping.