How many bytes does the EthernetII header (without VLAN TAG) include?

When testing the average transmit optical power of an optical interface, which of the following descriptions are incorrect?

Is the following description correct? The OLT supports directly copying the user message priority as the priority of forwarding messages, and also supports the local setting of the priority directly on the OLT.

Is the following description correct? Version rollback generally includes three steps: 1. Load the original version of the package file; 2. Load the original version database backed up before the upgrade; 3. Reset the system.

What fax modes are supported in UA5000?