The SONET/SDH OC12/4xOC3 & STM-4/4xSTM-1 Framer core implements the STS-12/4xSTS-3 and STM-4/4xSTM-1 layer function of Telcordia GR-253-CORE/ITU-T G.707, supporting data rate at 622M/s.
In the source direction, the payload is loaded by the SPE handler which sends out data request to the source client. The SPE handler wraps the payloads into a SPE envelope. The SPE envelope is then framed with STS or STM frame structure by the Source Frame Generator. The TOH generator provides all transport overhead information (TOH) to the Source Frame Generator. The TOH can be programmed by software or altered by External TOH Insert Port.
In the sink direction, the Sink Framer delineates the STS or STM frame structure and extracts the TOH and sends the TOH to TOH processor for alarm and OAM processing. All TOH bytes are made available to the External TOH Extract Port. The SPE envelope is sent to the Payload Extractor for payload extraction.