Result: standard mapping
How many E3s are in an OTU1?
An OTU1 carries 48 E3s, per ITU-T G.709 and ITU-T G.707. This path maps STM-16 into ODU1 as a client, then follows that client's tributaries.
48
E3s in an OTU1
Working
OTU1 → 1 × ODU1 → 1 × STM-16 → 16 × STM-1 → 3 × E3
- 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 × STM-16 in each ODU1 ITU-T G.709Client mappingCBR STM-16 mapped into OPU1.
- 16 × STM-1 in each STM-16 ITU-T G.70716 × STM-1.
- 3 × E3 in each STM-1 ITU-T G.707Three VC-3s, each carrying an E3.
- 1 ODU1
- 1 × 1 = 1 STM-16
- 1 × 1 × 16 = 16 STM-1s
- 1 × 1 × 16 × 3 = 48 E3s
Leftover capacity
1.016393143 Gbit/s of each OTU1 line rate (2.666057143 Gbit/s) sits outside 48 × 34.368 Mbit/s of E3 line rate (1.649664 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 77.57, which floors to 77 E3s by bit rate only. The standard mapping is 48. Use the mapping.