OC-12/STM-4 at 622.08 Mbps is four times OC-3 speed, carried over single-mode fiber with LC connectors. Used in metropolitan SONET rings and SDH equipment for higher-capacity carrier transport.
| Pin | Name | Function | Type |
|---|---|---|---|
| TX | TX | OC-12 optical transmit | BUS |
| RX | RX | OC-12 optical receive | BUS |