23To do… Use the command… RemarksEnable global MACaddress learningundo mac-address mac-learningdisableOptionalEnabled by default.Enter interface view orport group view• Enter Layer 2 Ethernet interfaceview or Layer 2 aggregateinterface view:interface interface-typeinterface-number• Enter port group view:port-group manual port-group-nameRequiredUse either command.Settings in Layer 2 Ethernet interface viewor Layer 2 aggregate interface view takeeffect on the interface only. Settings inport group view take effect on all memberports in the port group.Disable MAC addresslearning on the interfaceor all ports in the portgroupmac-address mac-learning disable RequiredEnabled by default.NOTE:• When MAC address learning is disabled, the obtained MAC addresses remain valid until they age out.• For configuration about port groups, see the chapter “Ethernet interface configuration.”Configuring the aging timer for dynamic MAC address entriesThe MAC address table uses an aging timer for dynamic MAC address entries for security and efficientuse of table space. If a dynamic MAC address entry has failed to update before the aging timer expires,the device deletes the entry. This aging mechanism ensures that the MAC address table can quicklyupdate to accommodate the latest network changes.Set the aging timer appropriately. Too long an aging interval might cause the MAC address table toretain outdated entries, exhaust the MAC address table resources, and fail to update its entries toaccommodate the latest network changes. Too short an interval might result in removal of valid entries,causing unnecessary broadcasts, which might affect device performance.Follow these steps to configure the aging timer for dynamic MAC address entries:To do… Use the command… RemarksEnter system view system-view —Configure the aging timerfor dynamic MAC addressentriesmac-address timer{ aging seconds |no-aging }Optional300 seconds by default.The no-aging keyword disables the aging timer.You can reduce broadcasts on a stable network by disabling the aging timer to prevent dynamic entriesfrom unnecessarily aging out. By reducing broadcasts, you improve not only network performance, butalso security, because you reduce the chances that a data packet will reach unintended destinations.Configuring the MAC learning limit on portsTo prevent the MAC address table from getting too large, you can limit the number of MAC addressesthat a port can obtain.
