# MAC Change Messages

## Navigation

1. Select Device > Configure > MAC Notification > History Table.

2. With a table entry selected, click MAC Change Messages.

cmnHistMacChangedMsg, the MIB object upon which this dialog box is based, describes what happened during a particular MAC change notification event. It consists of several tuples packed together as follows: <tuple1><tuple2> and so on. Each tuple consists of an 11 octet string that's composed of the following components: <operation><VLAN><MAC><dot1dBasePort>. These components are defined below.

### Operation (Operation)

This object, which is 1 octet in length, indicates what operation took place. There are three possible values:

- 0—indicates the end of a MIB object

- 1—a MAC address was learned

- 2—a MAC address was removed

### VLAN (VLAN)

Numerical identifier of the VLAN to which a MAC address belongs. This object is 2 octets in length.

### MAC Addr (MAC Addr)

Indicates the Layer 2 MAC address. This object is 6 octets in length.

### dot1dBasePort (dot1dBasePort)

The value of dot1dBasePort for the interface from which a MAC address was learned. This object is 2 octets in length.