Configuring Port and VLAN Mirroring

The Port and VLAN Mirroring Page enables configuring the port and VLAN mirroring feature. This feature is useful when attempting to debug network issues and there is a need to capture the traffic between two stations.

Port and VLAN mirroring monitors and mirrors network traffic by forwarding copies of incoming and outgoing packets from a single port to a monitoring port. Port mirroring can be used as diagnostic tool and/or a debugging feature. Port mirroring also enables performance monitoring.

Configure port mirroring by selecting a port to which to copy all packets and the ports from which packets are copied.

To enable the usage of traffic analysis and monitoring devices, you may specify that a desired target port receives a copy of all traffic passing through any designated VLAN. By default VLAN mirroring is disabled.

The analyzer port (target port for VLAN mirroring) is the same as for the port-based mirroring.

A packet that is received on a network port (packets sent by the CPU are not mirrored) and is assigned to a VLAN that is subject to mirroring, is mirrored to the analyzer port even if the packet was trapped to CPU or discarded.

BPDU packets are also subject to mirroring.

The analyzer port for VLAN mirroring should be the same for all the mirrored VLANs and should be the same port as the analyzer port for port ingress mirroring traffic.

You may enter the source VLAN and destination port. Up to eight sources (VLANs, ports or a mix between them) may be entered.

Mirroring does not guarantee that all the traffic of the source port is received on the monitor port, since it can be monitoring several ports.

To enable port and VLAN mirroring:

Click Administration > Diagnostics > Port and VLAN Mirroring. The Port and VLAN Mirroring Page opens.

This page contains the following fields:

Destination Port — Select the port to which traffic is to be copied.

The source ports mirrored on the destination port are displayed along with the following fields:

Source Port and VLAN — Displays the interface from which traffic is to be analyzed.
Type — Is this an ingress, egress or both ingress and egress interface.
Status — Displays whether the interface is up or not.

Adding Port and VLAN Mirroring

To add a port or VLAN to be mirrored, click Add in the Port and VLAN Mirroring Page. The Add Port/VLAN Mirroring Page opens.

This page contains the following fields:

Source Port — Select the port from which traffic is to be mirrored (analyzed).
Type — Select whether ingress, egress or both types of ports are mirrored. The possible options are:
RxOnly — Defines the port mirroring on receiving ports.
TxOnly — Defines the port mirroring on transmitting ports.
Tx and Rx — Defines the port mirroring on both receiving and transmitting ports.
Source VLAN — Select the VLAN from which traffic is to be analyzed.