Issue Description
Q：
Do AR46 serials support port mirroring? If AR46 serials support port mirroring, what should be noticed?
Handling Process
A：
1. AR46 serials of VRP3.40-R201 and later versions support port mirroring.
2. Pacl mirrored packets are classified into physical layer packets and IP layer packets. A port can be configured with two types of mirroring on the physical layer and IP layer.
3. AR46 serials support local mirroring and remote mirroring. Only one type of mirroring mode can be used.
4. Multiple mirrored ports can be mirrored to the same mirroring port.
5. The mirroring port must be Ethernet port.
6. The same interface cannot function as mirroring port and mirrored port at the same time.
7. The command for physical layer mirroring cannot be configured on the sub-interface or logical interface.
