31Configuring MAC InformationOverviewIntroduction 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, the devicesends 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 MAC authentication, MAC addresses thatpass 802.1X authentication, MAC addresses matching OUI addresses in the voice VLAN feature, andsecure 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"Voice VLAN configuration."Enabling MAC Information globallyStep Command Remarks1. Enter system view. system-view N/A2. Enable MAC Informationglobally. mac-address information enable Disabled by default.Enabling MAC Information on an interfaceTo enable MAC Information on an Ethernet interface, enable MAC Information globally first.To enable MAC Information on an interface:
