Huawei OSN3500 is a STM-64 level MSTP, It have 15 service slots and can MAX support 12*STM-64 interface. OSN3500 Subrack comes with two PIU (Power Interface Unit), one AUX (System Auxiliary Interface Board), others system board and service board are configurable. Its Clock Synchronization function includes:
Line clock source
Tributary clock source
Two external clock inputs/outputs (2 MHz or 2 Mbit/s)