3Com S7906E Command Reference Manual page 82

Features
Mirroring
Port mirroring copies packets passing through a port to another port
connected with a monitoring device for packet analysis to help implement
network monitoring and troubleshooting. Traffic mirroring is implemented
by a QoS policy, which defines certain match criteria to match the packets
to be mirrored and defines the action of mirroring such packets to the
specified destination.This document introduces the commands for:
Local port mirroring configuration
Remote port mirroring configuration
On the S7900E series switches, traffic mirroring is achieved mainly
through QoS policies and remote port mirroring. For QoS policy
configuration commands, refer to QoS Commands in the QoS Volume.
Description