What an OC-12 contains
An OC-12 carries 8,064 DS0s, per Telcordia GR-253 and ANSI T1.107.
OC-12 → 12 × OC-1 (STS-1) → 28 × DS1 → 24 × DS0
- 12 OC-1s
- 12 × 28 = 336 DS1s
- 12 × 28 × 24 = 8,064 DS0s
E1 mapping: 252 E1s, which is 7,560 voice channels at 30 per E1. E1s in an OC-12.
Down to DS0
- 12 × OC-1 (STS-1) Telcordia GR-25312 × OC-1 (STS-1). Channelized OC-12 is 12 STS-1s.
- 28 × DS1 Telcordia GR-253Seven VT groups × four VT1.5 (DS1).
- 24 × DS0 ANSI T1.10724 payload timeslots. The framing bit adds 8 kbit/s and brings the line rate to 1.544 Mbit/s.
- 1 × DS3 Telcordia GR-253Asynchronous DS3 mapping into the STS-1 synchronous payload envelope.
- 7 × DS2 Telcordia GR-253Seven VT groups, one VT6 (DS2) each.
- 21 × E1 Telcordia GR-253Seven VT groups × three VT2 (E1).
- 28 × DS1 Telcordia GR-253Seven VT groups × four VT1.5 (DS1).
- 4 × OC-3 Telcordia GR-2534 × OC-3. Channelized OC-12 is 12 STS-1s.