Result: standard mapping
How many E4s are in a STM-4?
A STM-4 carries 4 E4s, per ITU-T G.707. This is a client mapping of E4 into STM-1.
4
E4s in a STM-4
Working
STM-4 → 4 × STM-1 → 1 × E4
- 4 × STM-1 in each STM-4 ITU-T G.7074 × 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.
- 4 STM-1s
- 4 × 1 = 4 E4s
Leftover capacity
65.024 Mbit/s of each STM-4 line rate (622.080 Mbit/s) sits outside 4 × 139.264 Mbit/s of E4 line rate (557.056 Mbit/s). That remainder is overhead, fixed stuff or justification. It is not another whole tributary.