Result: standard mapping
How many OC-3s are in an OTU1?
An OTU1 carries 16 OC-3s, per ITU-T G.709 and Telcordia GR-253. This path maps OC-48 into ODU1 as a client, then follows that client's tributaries.
16
OC-3s in an OTU1
Working
OTU1 → 1 × ODU1 → 1 × OC-48 → 16 × OC-3
- 1 × ODU1 in each OTU1 ITU-T G.709The OTU1 frame carries exactly one ODU1. The line-rate gap is OTU overhead and FEC.
- 1 × OC-48 in each ODU1 ITU-T G.709Client mappingCBR OC-48, the same client rate as STM-16, mapped into OPU1.
- 16 × OC-3 in each OC-48 Telcordia GR-25316 × OC-3. Channelized OC-48 is 48 STS-1s.
- 1 ODU1
- 1 × 1 = 1 OC-48
- 1 × 1 × 16 = 16 OC-3s
Leftover capacity
177.737143 Mbit/s of each OTU1 line rate (2.666057143 Gbit/s) sits outside 16 × 155.520 Mbit/s of OC-3 line rate (2.488320 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 17.14, which floors to 17 OC-3s by bit rate only. The standard mapping is 16. Use the mapping.