3Com 4200G, 5500G, 4210 manual Remote port mirroring application

Remote Port Mirroring Configuration 231

Remote Port Mirroring Remote port mirroring does not require the source and destination ports to be on

Configuration 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.

A special VLAN, called remote-probe VLAN, is needed to implement remote port mirroring. 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 that you can monitor packets received on and sent from the source switch on the destination switch. Figure 68 illustrates the implementation of remote port mirroring.

Figure 68 Remote port mirroring application

Remote-probe VLAN

Source Switch

Intermediate Switch

Destination

Switch

Source Port Reflector Port Trunk Port Destination Port

Switches involved in remote port mirroring play one of the following three roles:

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

■Intermediate switch: Switches between the source switch and the destination switch on the network. An intermediate switch forwards mirrored traffic to the next intermediate switch or the destination switch through the remote-probe VLAN. No intermediate switch is present if the source switch and the destination switch are directly connected to each other.

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