(single) Is the following description correct? When upgrading the version, use the database upgrade tool to upgrade the dat file to the high version. You can also use the upgrade tool to lower the high version of the dat file to the lower version.

(single) In the EPON network, what management and maintenance channel does the OLT use to configure and maintain the terminal equipment?

(single) Is the following description correct? VPI/VCI is a global concept and must be unique under the interface.

Which of the following description is wrong about MA5616 description?

(single) Is the following description correct? The link layer defines electrical and mechanical processes and functions to enable activation, maintenance, and removal of lines when systems are connected at both ends.