Result: standard mapping
How many E1s are in an OC-768?
An OC-768 carries 16,128 E1s, per Telcordia GR-253.
16,128
E1s in an OC-768
Working
OC-768 → 768 × OC-1 (STS-1) → 21 × E1
- 768 × OC-1 (STS-1) in each OC-768 Telcordia GR-253768 × OC-1 (STS-1). Channelized OC-768 is 768 STS-1s.
- 21 × E1 in each OC-1 (STS-1) Telcordia GR-253Seven VT groups × three VT2 (E1).
- 768 OC-1s
- 768 × 21 = 16,128 E1s
Leftover capacity
6.782976 Gbit/s of each OC-768 line rate (39.813120 Gbit/s) sits outside 16,128 × 2.048 Mbit/s of E1 line rate (33.030144 Gbit/s). That remainder is overhead, fixed stuff or justification. It is not another whole tributary.
By bit rate only
Dividing the line rates gives 19,440, which floors to 19,440 E1s by bit rate only. The standard mapping is 16,128. Use the mapping.