28MAC Information configurationOverviewIntroduction to MAC InformationTo monitor a network, you must monitor users who are joining and leaving the network. Because a MACaddress uniquely identifies a network user, you can monitor users who are joining and leaving a networkby monitoring their MAC addresses.With the MAC Information function, Layer 2 Ethernet ports send Syslog or trap messages to the monitorend in the network when they obtain or delete MAC addresses. By analyzing these messages, themonitor end can monitor users who are accessing the network.How MAC Information worksWhen a new MAC address is obtained or an existing MAC address is deleted on a device, the devicewrites related information about the MAC address to the buffer area used to store user information.When the timer set for sending MAC address monitoring Syslog or trap messages expires, or when thebuffer reaches capacity, the device sends the Syslog or trap messages to the monitor end.The device writes information and sends messages only for the following MAC addresses: automaticallylearned source MAC addresses, MAC addresses that pass or fail MAC authentication, MAC addressesthat pass 802.1X authentication, MAC addresses matching OUI addresses in the voice VLAN feature,and secure MAC addresses. The device does not write information or send messages for blackhole MACaddress, static MAC addresses, dynamic MAC addresses that are manually configured, multicast MACaddresses, and local MAC addresses.For more information about MAC authentication, 802.1X, and secure MAC addresses in port security,see Security Configuration Guide. For more information about voice VLAN and OUI addresses, see thechapter “Voice VLAN configuration.”Configuring MAC InformationEnabling MAC Information globallyFollow these steps to enable MAC Information globally:To do… Use the command… RemarksEnter system view system-view —Enable MAC Information globally mac-address information enable RequiredDisabled by default.Enabling MAC Information on an interfaceFollow these steps to enable MAC Information on an interface:
