Dell PowerConnect 55xx Systems User Guide 411Port MirroringSwitches usually only forward frames to relevant ports. To monitor traffic,either for information gathering, such as statistical analysis, or fortroubleshooting higher-layer protocol operation, the Mirroring featureforwards frames to a monitoring port.Mirroring provides the ability to specify that a desired destination (target)port will receive a copy of all traffic passing through designated source ports.The frames arriving at the destination port are copies of the frames passingthrough the source port at ingress, prior to any switch action.It is possible to specify several source ports to be monitored by a single targetport. However, in this case, the traffic sent to the target port is placed in thetarget port's queues on a first come, first served basis, and any excess traffic issilently discarded. This may mean that the traffic actually seen by any deviceattached to the target port is an arbitrarily selected subset of the actual trafficgoing through the source ports.Port mirroring is only relevant to physical ports. Therefore, if you want a LAGto function as the source of a port mirroring session, the member ports mustbe individually specified as sources.Up to eight sources can be mirrored. This can be any combination of eightindividual ports.Before configuring Port Mirroring, note the following:• Monitored ports cannot operate faster than the monitoring port.• All Rx/Tx packets should be monitored to the same port.Destination Port RestrictionsThe following restrictions apply to destination ports:• Destination ports cannot be configured as source ports.• Destination ports cannot be a member of a LAG.• IP interfaces cannot be configured on the destination port.• GVRP cannot be enabled on the destination port.• The destination port cannot be a member of a VLAN.• Only one destination port can be defined.
