MAC Address Learning Control
Hackers can send a large number of packets with different source MAC addresses to a switch, causing useless MAC addresses to fill up the MAC address table. As a result, the switch cannot learn source MAC addresses of valid packets and the switch wastes bandwidth broadcasting these invalid packets.
The switch has the following MAC address learning control methods to protect against this issue:
Disabling MAC address learning on a VLAN or an interface
Limiting the number of MAC address entries that can be learned from a VLAN or an interface
| MAC Address Learning Control Method | Principle | Application Scenario |
|---|---|---|
Disabling MAC address learning on a VLAN or an interface |
After MAC address learning is disabled on a VLAN or an interface, the switch does not learn new dynamic MAC address entries on that VLAN or interface. The learned dynamic MAC address entries will age out when the aging time expires. They can also be manually deleted using commands. |
|
Limiting the number of MAC address entries that can be learned from a VLAN or an interface |
The switch can only learn a specified number of MAC address entries from a VLAN or an interface. When the number of learned MAC address entries reaches the limit, the switch generates an alarm to notify the network administrator. After that, the switch cannot learn new MAC address entries from the VLAN or interface and discards any packets with source MAC addresses not in the MAC address table. |