Result: standard mapping
How many E2s are in an OTU3?
An OTU3 carries 3,072 E2s, per ITU-T G.709, ITU-T G.707 and ITU-T G.702. This path maps STM-256 into ODU3 as a client, then follows that client's tributaries.
3,072
E2s in an OTU3
Working
OTU3 → 1 × ODU3 → 1 × STM-256 → 256 × STM-1 → 3 × E3 → 4 × E2
- 1 × ODU3 in each OTU3 ITU-T G.709The OTU3 frame carries exactly one ODU3.
- 1 × STM-256 in each ODU3 ITU-T G.709Client mappingCBR STM-256 mapped into OPU3.
- 256 × STM-1 in each STM-256 ITU-T G.707256 × STM-1.
- 3 × E3 in each STM-1 ITU-T G.707Three VC-3s, each carrying an E3.
- 4 × E2 in each E3 ITU-T G.702Four E2s.
- 1 ODU3
- 1 × 1 = 1 STM-256
- 1 × 1 × 256 = 256 STM-1s
- 1 × 1 × 256 × 3 = 768 E3s
- 1 × 1 × 256 × 3 × 4 = 3,072 E2s
Leftover capacity
17.066157559 Gbit/s of each OTU3 line rate (43.018413559 Gbit/s) sits outside 3,072 × 8.448 Mbit/s of E2 line rate (25.952256 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 5,092.14, which floors to 5,092 E2s by bit rate only. The standard mapping is 3,072. Use the mapping.