Result: standard mapping
How many E1s are in an ODU4?
An ODU4 carries 40,320 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.
40,320
E1s in an ODU4
Working
ODU4 → 10 × ODU2 → 1 × STM-64 → 64 × STM-1 → 63 × E1
- 10 × ODU2 in each ODU4 ITU-T G.709Ten ODU2s use all 80 tributary slots, eight slots each.
- 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.
- 10 ODU2s
- 10 × 1 = 10 STM-64s
- 10 × 1 × 64 = 640 STM-1s
- 10 × 1 × 64 × 63 = 40,320 E1s
Leftover capacity
22.219085815 Gbit/s of each ODU4 line rate (104.794445815 Gbit/s) sits outside 40,320 × 2.048 Mbit/s of E1 line rate (82.575360 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 51,169.16, which floors to 51,169 E1s by bit rate only. The standard mapping is 40,320. Use the mapping.