3Com WX3000 operation manual Local Port Mirroring, Remote Port Mirroring

zVLAN-based mirroring: a device copies packets of a specified VLAN to the destination port.

Local Port Mirroring

In local port mirroring, packets passing through one or more source ports of a device are copied to the destination port on the same device for packet analysis and monitoring. In this case, the source ports and the destination port must be located on the same device.

Remote Port Mirroring

Remote port mirroring does not require the source and destination ports to be on the same device. The source and destination ports can be located on multiple devices across the network. Therefore, administrators can monitor the traffic on remote devices conveniently.

To implement remote port mirroring, a special VLAN, called remote-probe VLAN, is needed. All mirrored packets are sent from the reflector port of the source switch to the monitor port (destination port) of the destination switch through the remote-probe VLAN, so as to implement the monitoring of packets received on and sent from the source switch on the destination switch. Figure 1-2 illustrates the implementation of remote port mirroring.

Figure 1-2Remote port mirroring application

Source Switch

Remote-probe VLAN

Intermediate Switch

Destination

Switch

Source Port Reflector port Trunk port Destination port

The switches involved in the remote port mirroring implementation play the following three roles.

zSource switch: The monitored port resident switch. It copies traffic to the reflector port, which then transmits the traffic to an intermediate switch or destination switch through the remote-probe VLAN.

zIntermediate switch: Switches between the source switch and destination switch on the network. An intermediate switch forwards mirrored traffic flows to the next intermediate switch or the destination switch through the remote-probe VLAN. No intermediate switch is present if the source and destination switches directly connect to each other.

zDestination switch: The remote mirroring destination port resident switch. It forwards mirrored traffic flows it received from the remote-probe VLAN to the monitoring device through the destination port.

Table 1-1 describes how the ports on various switches are involved in the mirroring operation.

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