Result: standard mapping
How many DS0s are in a DS3?
A DS3 carries 672 DS0s, per ANSI T1.107.
672
DS0s in a DS3
Working
DS3 → 28 × DS1 → 24 × DS0
- 28 × DS1 in each DS3 ANSI T1.10728 DS1s, which is 7 DS2s × 4 DS1s.
- 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.
- 28 DS1s
- 28 × 24 = 672 DS0s
Leftover capacity
1.728 Mbit/s of each DS3 line rate (44.736 Mbit/s) sits outside 672 × 64 kbit/s of DS0 line rate (43.008 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 699, which floors to 699 DS0s by bit rate only. The standard mapping is 672. Use the mapping.