Managing the MAC Address Table 251

Perform the following configuration in system view.

Table 271 Setting MAC Address Table Entries

Operation

Command

 

 

Add or modify an address entry

mac-address { static dynamic }

 

hw-addrinterface {

 

interface-name interface-type

 

interface-num }

Delete an address entry

undo mac-address [ { static

 

dynamic } mac-addressinterface {

 

interface-name interface-type

 

interface-num } vlan-id ]

 

 

Disabling or Enabling Global MAC Address Learning

With the address learning function, an Ethernet switch can learn new MAC addresses. When it receives a packet destined for a MAC address it has already learned, the switch forwards the packet directly, instead of flooding all ports.

Sometimes, for the sake of security, it is necessary to disable the address learning function. A common threat is from hackers who attack the switch with packets from different source MAC addresses, thereby exhausting the address table resources and making it impossible for the switch to update the MAC address table to reflect network changes. Such an attack can be avoided by disabling the MAC address learning function.

You can use the following commands to disable or enable the MAC address learning globally.

Perform the following configuration in system view.

Table 272 Disabling or Enabling the MAC Address Learning

Operation

Command

 

 

Disable the MAC address learning

mac-address mac-learning disable

Enable the MAC address learning

undo mac-address mac-learning

 

disable

 

 

By default, the MAC address learning function is enabled.

Disabling or Enabling MAC Address Learning on a Port

After the MAC address learning has been enabled globally, you can disable it on individual ports.

Use the following commands to disable the MAC address learning on a specified port.

Perform the following configurations in the Ethernet port view.

Table 273 Disable/Enable the MAC Address Learning

Operation

Command

 

 

Disable the MAC address learning

mac-address mac-learning disable

Enable the MAC address learning

undo mac-address mac-learning

 

disable

 

 

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3Com 10014298 Disabling or Enabling Global MAC Address Learning, By default, the MAC address learning function is enabled