Result: standard mapping
How many DS0s are in a STM-1?
A STM-1 carries 2,016 DS0s, per ITU-T G.707 and ANSI T1.107.
2,016
DS0s in a STM-1
Working
STM-1 → 84 × DS1 → 24 × DS0
- 84 × DS1 in each STM-1 ITU-T G.70784 VC-11 tributaries: 3 TUG-3 × 7 TUG-2 × 4 TU-11.
- 24 × DS0 in each DS1 ANSI T1.10724 payload timeslots. The framing bit adds 8 kbit/s and brings the line rate to 1.544 Mbit/s.
- 84 DS1s
- 84 × 24 = 2,016 DS0s
Leftover capacity
26.496 Mbit/s of each STM-1 line rate (155.520 Mbit/s) sits outside 2,016 × 64 kbit/s of DS0 line rate (129.024 Mbit/s). That remainder is overhead, fixed stuff or justification. It is not another whole tributary.
By bit rate only
Dividing the line rates gives 2,430, which floors to 2,430 DS0s by bit rate only. The standard mapping is 2,016. Use the mapping.