11-111 Port Mirroring ConfigurationThis chapter includes these sections:z Introduction to Port Mirroringz Configuring Local Port Mirroringz Configuring Layer 2 Remote Port Mirroringz Configuring Layer 3 Remote Port Mirroringz Displaying and Maintaining Port Mirroringz Port Mirroring Configuration ExamplesIntroduction to Port MirroringPort mirroring is the process of copying the packets that pass through a port/CPU (a mirroringport/CPU) to another port (the monitor port) that is connected with a monitoring device for packetanalysis.You can select to port-mirror inbound, outbound, or bidirectional traffic on a port/CPU as needed.Classification of Port MirroringPort mirroring falls into the following types:z Local port mirroring: In local port mirroring, the mirroring ports/CPUs and the monitor port arelocated on the same device.z Layer 2 remote port mirroring: In Layer 2 remote port mirroring, the mirroring ports/CPUs and themonitor port are located on different devices but are on the same Layer 2 network.z Layer 3 remote port mirroring: In Layer 3 remote port mirroring, the mirroring ports/CPUs and themonitor port are separated by IP networks.z Because a monitor port can monitor multiple ports, in some case, it may receive severalduplicates of a packet. For example, suppose that Port 1 is monitoring bidirectional traffic on Ports2 and 3 of the same device. If a packet travels from Port 2 to Port 3, two duplicates of the packetwill be received on Port 1.z Given an S5820X&S5800 series switch, if incoming traffic is mirrored, the mirrored traffic is sentwith the same VLAN tag (if any) as the original traffic; if the outgoing traffic is mirrored, themirrored traffic carries the same VLAN tag as the original traffic did before it was sent out themirroring ports.
