Result: standard mapping
How many E1s are in an OTU2?
An OTU2 carries 4,032 E1s, 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.
4,032
E1s in an OTU2
Working
OTU2 → 1 × ODU2 → 1 × STM-64 → 64 × STM-1 → 63 × E1
- 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.
- 64 × STM-1 in each STM-64 ITU-T G.70764 × STM-1.
- 63 × E1 in each STM-1 ITU-T G.70763 VC-12 tributaries: 3 TUG-3 × 7 TUG-2 × 3 TU-12.
- 1 ODU2
- 1 × 1 = 1 STM-64
- 1 × 1 × 64 = 64 STM-1s
- 1 × 1 × 64 × 63 = 4,032 E1s
Leftover capacity
2.451689316 Gbit/s of each OTU2 line rate (10.709225316 Gbit/s) sits outside 4,032 × 2.048 Mbit/s of E1 line rate (8.257536 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 5,229.11, which floors to 5,229 E1s by bit rate only. The standard mapping is 4,032. Use the mapping.