Result: standard mapping
How many E0s are in a STM-64?
A STM-64 carries 120,960 E0s, per ITU-T G.707 and ITU-T G.704.
120,960
E0s in a STM-64
Working
STM-64 → 64 × STM-1 → 63 × E1 → 30 × E0
- 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.
- 30 × E0 in each E1 ITU-T G.70430 voice channels in 32 timeslots. TS0 is framing and TS16 is channel-associated signalling.
- 64 STM-1s
- 64 × 63 = 4,032 E1s
- 64 × 63 × 30 = 120,960 E0s
Leftover capacity
2.211840 Gbit/s of each STM-64 line rate (9.953280 Gbit/s) sits outside 120,960 × 64 kbit/s of E0 line rate (7.741440 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 155,520, which floors to 155,520 E0s by bit rate only. The standard mapping is 120,960. Use the mapping.