Result: standard mapping
How many E1s are in a STM-64?
A STM-64 carries 4,032 E1s, per ITU-T G.707.
4,032
E1s in a STM-64
Working
STM-64 → 64 × STM-1 → 63 × E1
- 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.
- 64 STM-1s
- 64 × 63 = 4,032 E1s
Leftover capacity
1.695744 Gbit/s of each STM-64 line rate (9.953280 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 4,860, which floors to 4,860 E1s by bit rate only. The standard mapping is 4,032. Use the mapping.