Result: standard mapping
How many E0s are in an OC-1?
An OC-1 carries 630 E0s, per Telcordia GR-253 and ITU-T G.704.
630
E0s in an OC-1
Working
OC-1 (STS-1) → 21 × E1 → 30 × E0
- 21 × E1 in each OC-1 (STS-1) Telcordia GR-253Seven VT groups × three VT2 (E1).
- 30 × E0 in each E1 ITU-T G.70430 voice channels in 32 timeslots. TS0 is framing and TS16 is channel-associated signalling.
- 21 E1s
- 21 × 30 = 630 E0s
Leftover capacity
11.520 Mbit/s of each OC-1 line rate (51.840 Mbit/s) sits outside 630 × 64 kbit/s of E0 line rate (40.320 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 E0s by bit rate only. The standard mapping is 630. Use the mapping.