Huawei OpticX OSN 3500 protection mechanism includes Equipment level of protection and network level of protection.firstly, Huawei OptiX OSN 9500 provide the network level of self-healing protection mode.A)1+1 or 1:N LMSP. Switching time:0~50ms.B)supporting the reuse of two fiber and four fiber ring protection MSP（Multiplex Section Protection）STM-64、STM-16, both can use two fiber and four fiber.Switching time:0～50ms.C) sub-network connection protect (SNCP). Switching time:0～50ms.D)Mesh networking protection and reroute protection. Switching time:50ms~a few minutes. Secondly, Huawei OptiX OSN 3500 Provide the equipment level of protection, Cross board 1 + 1 hot backup, The clock plate 1 + 1 hot backup, 1 + 1 hot backup of master control board,providing key power backup, veneer implementation circuit board, JCOM board or light power amplifier board power supply centralized backup.