Result: standard mapping
How many E4s are in a STM-64?
A STM-64 carries 64 E4s, per ITU-T G.707. This is a client mapping of E4 into STM-1.
64
E4s in a STM-64
Working
STM-64 → 64 × STM-1 → 1 × E4
- 64 × STM-1 in each STM-64 ITU-T G.70764 × STM-1.
- 1 × E4 in each STM-1 ITU-T G.707Client mappingAsynchronous E4 mapped into the C-4 / VC-4. This client holds 64 E1s internally; the VC-12 tributary count of an STM-1 is 63.
- 64 STM-1s
- 64 × 1 = 64 E4s
Leftover capacity
1.040384 Gbit/s of each STM-64 line rate (9.953280 Gbit/s) sits outside 64 × 139.264 Mbit/s of E4 line rate (8.912896 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 71.47, which floors to 71 E4s by bit rate only. The standard mapping is 64. Use the mapping.