HUAWEI STM-4 (622M) optical interface board supports the implementation of sending and receiving STM-4 signal, STM-4 signal of the photoelectric conversion is completed, the overhead byte extraction and insertion, and reporting to the alarm on the line. STM-4 optical interface board SDH board are: SL4, SL4A, SLD4, SLD4A, SLQ4, SLQ4A, each type of plate distance distance, according to customer demand, the corresponding configuration panel.