VLAN Mirrors

Creating a VLAN and setting a mirror for the VLAN allows you to monitor all traffic to your specified VLAN interface. For example, you could track all data traveling in and out of a confidential group of workstations, such as a Finance VLAN, by analyzing only one connection point. Considerations when configuring VLAN mirrors include:

• A one-to-many or many-to-one VLAN mirror is considered a single destination port.
• Many-to-one mapping allows multiple VLANs to be sent to one specific destination port.
• Oversubscribed traffic will be dropped.

A VTAP interface provides the data source input of a VLAN mirror. VTAP creation is the mechanism for adding a MIB-II interface table entry for a VLAN. A VLAN will not have a MIB-II ifIndex if a VTAP interface does not exist for it. Use the set vlan interface command to create a VTAP interface.