1-11 Port Mirroring ConfigurationWhen configuring port mirroring, go to these sections for information you are interested in:z Introduction to Port Mirroringz Configuring Local Port Mirroringz Configuring Remote Port Mirroringz Displaying and Maintaining Port Mirroringz Port Mirroring Configuration ExamplesIntroduction to Port MirroringPort mirroring is to copy the packets passing through a port (called a mirroring port) to another port(called the monitor port) connected with a monitoring device for packet analysis.You can select to port-mirror inbound, outbound, or bidirectional traffic on a port/VLAN as needed.Classification of Port MirroringPort mirroring can be local or remote.z In local port mirroring, the mirroring port or ports and the monitor port are located on the samedevice.z In remote port mirroring, the mirroring port or ports and the monitor port can be located on the samedevice or different devices. Currently, remote port mirroring can be implemented only at Layer 2.As a monitor port can monitor multiple ports, it may receive multiple duplicates of a packet in somecases. Suppose that port P 1 is monitoring bidirectional traffic on ports P 2 and P 3 on the same device.If a packet travels from P 2 to P 3, two duplicates of the packet will be received on P 1.Implementing Port MirroringPort mirroring is implemented through port mirroring groups. There are three types of mirroring groups:local, remote source, and remote destination.The following subsections describe how local port mirroring and remote port mirroring are implemented.Local port mirroringIn local port mirroring, all packets passing through a port can be mirrored. Local port mirroring isimplemented through a local mirroring group.As shown in Figure 1-1, packets on the mirroring port are mirrored to the monitor port for the datamonitoring device to analyze.
