This read-write Integer32 specifies which physical port on the D-Link Prime switch receives a copy of mirrored (monitored) traffic, i.e. the destination port for a port-mirroring session. An administrator sets this when configuring port monitoring for troubleshooting or traffic analysis, pointing mirrored packets to the port where a packet-capture tool or protocol analyzer is connected. For example, setting this object to port 24 would direct all mirrored traffic to physical port 24, where a network engineer's laptop running a packet sniffer could be plugged in.