Result: standard mapping
How many DS0s are in an OC-1?
An OC-1 carries 672 DS0s, per Telcordia GR-253 and ANSI T1.107.
672
DS0s in an OC-1
Working
OC-1 (STS-1) → 28 × DS1 → 24 × DS0
- 28 × DS1 in each OC-1 (STS-1) Telcordia GR-253Seven VT groups × four VT1.5 (DS1).
- 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
8.832 Mbit/s of each OC-1 line rate (51.840 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 810, which floors to 810 DS0s by bit rate only. The standard mapping is 672. Use the mapping.