84Port mirroring configurationIntroduction to port mirroringPort mirroring is the process of copying the packets passing through a port/CPU to the monitor portconnecting to a monitoring device for packet analysis.Terminologies of port mirroringMirroring sourceThe mirroring source can be one or more monitored ports or the CPUs. Packets (called “mirrored packets”)passing through them are copied to a port connecting to a monitoring device for packet analysis. Sucha port/CPU is called a “source port/CPU” and the device where the port or CPU resides is called a“source device”.Mirroring destinationThe mirroring destination is the destination port (also known as the monitor port) of mirrored packets andconnects to the data monitoring device. The device where the monitor port resides is called the“destination device”. The monitor port forwards mirrored packets to its connecting monitoring device.NOTE:A monitor port may receive multiple duplicates of a packet in some cases because it can monitor multiplemirroring sources. For example, assume that Port 1 is monitoring bidirectional traffic on Port 2 and Port 3on the same device. If a packet travels from Port 2 to Port 3, two duplicates of the packet will be receivedon Port 1.Mirroring directionThe mirroring direction indicates that the inbound, outbound, or bidirectional traffic can be copied on amirroring source.• Inbound: Copies packets received on a mirroring source.• Outbound: Copies packets sent out a mirroring source.• Bidirectional: Copies packets both received and sent on a mirroring source.Mirroring groupPort mirroring is implemented through mirroring groups, which fall into local, remote source, and remotedestination mirroring groups. For more information about the mirroring groups, see “Port mirroringclassification and implementation.”Reflector port, egress port, and remote probe VLANA reflector port, remote probe VLAN, and an egress port are used for Layer 2 remote port mirroring. Theremote probe VLAN specially transmits mirrored packets to the destination device. Both the reflector portand egress port reside on a source device and send mirrored packets to the remote probe VLAN. Theegress port must belong to the remote probe VLAN while the reflector port may not. For more informationabout the source device, destination device, reflector port, egress port, and remote probe VLAN, see“Port mirroring classification and implementation.”
