Result: standard mapping
How many OC-3s are in an OTU2?
An OTU2 carries 64 OC-3s, per ITU-T G.709 and Telcordia GR-253. This path maps OC-192 into ODU2 as a client, then follows that client's tributaries.
64
OC-3s in an OTU2
Working
OTU2 → 1 × ODU2 → 1 × OC-192 → 64 × OC-3
- 1 × ODU2 in each OTU2 ITU-T G.709The OTU2 frame carries exactly one ODU2.
- 1 × OC-192 in each ODU2 ITU-T G.709Client mappingCBR OC-192, the same client rate as STM-64, mapped into OPU2.
- 64 × OC-3 in each OC-192 Telcordia GR-25364 × OC-3. Channelized OC-192 is 192 STS-1s.
- 1 ODU2
- 1 × 1 = 1 OC-192
- 1 × 1 × 64 = 64 OC-3s
Leftover capacity
755.945316 Mbit/s of each OTU2 line rate (10.709225316 Gbit/s) sits outside 64 × 155.520 Mbit/s of OC-3 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 68.86, which floors to 68 OC-3s by bit rate only. The standard mapping is 64. Use the mapping.