TM is a terminal multiplexer, and its functions are: the line end inputs/outputs one STM-N signal, and the branch port can output/input multiple low-speed branch signals.

If a business call is required between two REG devices, E1 or E2 bytes can be used.

40G non-coherent systems and 100G coherent systems cannot be mixed.

When the working PQ1 board fails, the equipment will perform TFS protection switching. Which of the following statements about the switching process are correct? (Multiple choice)

User management can ensure the security of user information and system. The core of user management is to achieve decentralized management.