Configuring Port Mirroring

Port mirroring is used to monitor the network traffic that a port sends and receives. The Port Mirroring feature creates a copy of the traffic that the source port handles and sends it to a destination port. The source port is the port that is being monitored. The destination port is monitoring the source port. The destination port is where you would connect a network protocol analyzer to learn more about the traffic that is handled by the source port.

A port monitoring session includes one or more source ports that mirror traffic to a single destination port. 200 Series software supports a single port monitoring session. LAGs (port channels) cannot be used as the source or destination ports.

For each source port, you can specify whether to mirror ingress traffic (traffic the port receives, or RX), egress traffic (traffic the port sends, or TX), or both ingress and egress traffic.

The packet that is copied to the destination port is in the same format as the original packet on the wire. This means that if the mirror is copying a received packet, the copied packet is VLAN tagged or untagged as it was received on the source port. If the mirror is copying a transmitted packet, the copied packet is VLAN tagged or untagged as it is being transmitted on the source port.

After you configure the port mirroring session, you can enable or disable the administrative mode of the session to start or stop the probe port from receiving mirrored traffic.