MAC Address Table

Configuring Unicast Static MAC Address

You can configure static MAC addresses for unicast traffic. This feature improves security and reduces unknown unicast flooding.

To configure Unicast Static MAC address, run the following:

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            mac-address-table static unicast <destination mac address> vlan <vlan identifier(1-4094)> interface ethernet <slot>/<port>

For example:

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            switch (config) # mac-address-table static 00:11:22:33:44:55 vlan 1 interface ethernet 1/1

MAC learning may be disabled using the command mac-learning disable which is beneficial in the following situations:

To prevent denial-of-service attacks
To manage the available MAC address table space by controlling which interfaces can learn MAC addresses
To duplicate to a dedicated server (port7 in the figure below) all the packets that one host (host1; port1) sends to another (host2; port2), like in port mirroring. To accomplish this, MAC learning is disabled on port2. In this case the FDB does not obtain the MAC address of host2. Also, to prevent broadcast to every port, it is possible to configure a VLAN (VLAN 80) which ports 1, 2 and 7 are member of.

	mac-address-table aging-time <age> no mac-address-table aging-time Sets the maximum age of a dynamically learnt entry in the MAC address table. The no form of the command resets the aging time of the MAC address table to its default.
Syntax Description	age	10-1000000 seconds
Default	300
Configuration Mode	config
History	3.1.0600
Example	switch (config) # mac-address-table aging-time 50
Related Commands	show mac-address-table show mac-address-table aging time
Notes

	mac-address-table static <mac address> vlan <vlan> interface <if-type> <if-number> no mac-address-table static <mac address> vlan <vlan> interface <if-type> <if-number> Configures a static MAC address in the forwarding database. The no form of the command deletes a configured static MAC address from the forwarding database.
Syntax Description	mac address	Destination MAC address
	vlan	VLAN ID or VLAN range
	if-type	Ethernet or port-channel interface type
	if-number	Interface number (i.e. 1/1, 3)
Default	No static MAC addresses available in default
Configuration Mode	config
History	3.1.0600
Example	switch (config) # mac-address-table static aa:aa:aa:aa:aa:aa vlan 1 interface ethernet 1/7
Related Commands	show mac-address-table mac-address-table aging time
Notes	The no form of the command will not clear a dynamic MAC address. Dynamic MAC addresses are cleared using the “clear mac-address-table dynamic” command.

	mac-learning disable no mac-learning disable Disables MAC-address learning. The no form of the command enables MAC-address learning.
Syntax Description	N/A
Default	Enabled
Configuration Mode	config interface ethernet config interface port-channel
History	3.1.0600
Example	switch (config interface ethernet 1/1) # mac-learning disable
Related Commands
Notes	When adding a port to a LAG, the port needs to be aligned with the LAG’s configuration When removing a port from a LAG, the port remains in whichever configuration the LAG is in Disabling MAC learning is not supported on a local analyzer port. Disabling MAC learning is not supported on an IPL LAG.

	clear mac-address-table dynamic Clear the dynamic entries in the MAC address table.
Syntax Description	N/A
Default	N/A
Configuration Mode	config
History	3.1.0600
Example	switch (config) # clear mac-address-table dynamic
Related Commands	mac-address-table aging-time mac-address-table static show mac-address-table
Notes	This command does not clear the MAC addresses learned on the mgmt0 port. Static entries are deleted using the “no mac-address-table static” command.

	show mac-address-table [address <mac-address> \| <if-number> \| vlan [<vlan> \| range <range>] \| unicast] Displays the static and dynamic unicast and multicast MAC addresses for the switch. Various of filter options available.
Syntax Description	mac-address	Filters the table to a specific MAC address.
	if-number	Filters the table to a specific interface.
	vlan	Filters the table to a specific VLAN number (1-4094).
	range	Filters the table to a range of VLANs.
	unicast	Filters the table to a unicast addresses only.
Default	N/A
Configuration Mode	Any command mode
History	3.1.0600
	3.3.4500	Updated example
	3.8.1000	Updated syntax & example
Example	switch (config) # show mac-address-table Switch ethernet-default Vlan Mac Address Type Interface ---- ----------- ---- ------------ 1 00:00:00:00:00:01 Static Po5 1 00:00:3d:5c:fe:16 Dynamic Eth1/1 1 00:00:3d:5d:fe:1b Dynamic Eth1/2 Number of unicast: 2 switch (config) # show mac-address-table unicast ----------------------------------------------------------- Vlan Mac Address Type Port\Next Hop ----------------------------------------------------------- 1 24:8a:07:2e:61:72 Dynamic Eth1/31 6 00:00:11:22:33:44 Static 192.168.2.2(nve1) 6 00:00:66:77:88:99 Static 192.168.2.2(nve1)
Related Commands	mac-address-table static clear mac-address-table
Notes

	show mac-address-table aging-time Displays the MAC address table aging time.
Syntax Description	N/A
Default	N/A
Configuration Mode	Any command mode
History	3.1.0600
Example	switch (config) # show mac-address-table aging-time Mac Address Aging Time: 300
Related Commands	mac-address-table aging-time mac-address-table static clear mac-address-table
Notes	MAC addresses learned on the mgmt0 is not shown by this command.

	show mac-address-table interface [port-channel \| mlag-port-channel <if>] Displays the MAC address table of a LAG or an MPO.
Syntax Description	N/A
Default	N/A
Configuration Mode	Any command mode
History	3.6.4006
Example	switch (config) # show mac-address-table --------------------------------------------------- Vlan Mac Address Type Port --------------------------------------------------- 1 E4:1D:2D:37:11:22 Static Eth1/1 1 E4:1D:2D:37:3E:11 Static Po5 Number of unicast: 2 Number of multicast: 0 switch (config) # show mac-address-table interface port-channel 5 --------------------------------------------------- Vlan Mac Address Type Port --------------------------------------------------- 1 E4:1D:2D:37:3E:11 Static Po5 Number of unicast: 1 Number of multicast: 0
Related Commands	mac-address-table static clear mac-address-table
Notes

	show mac-address-table interface nve <nve-id> Displays MAC address table on specific NVE interface.
Syntax Description	nve-id	NVE ID
Default	N/A
Configuration Mode	Any command mode
History	3.8.1000
Example	switch (config) # show mac-address-table interface nve 1 ----------------------------------------------------- Vlan Mac Address Type Port\Next Hop ----------------------------------------------------- 60 E4:1D:2D:37:11:22 Dynamic Number of unicast(local): 1 Number of NVE: 1
Related Commands	protocol nve mac-address-table static clear mac-address-table
Notes	This command is not supported if NVE is not enabled.

	show mac-address-table summary Displays total number of unicast/multicast MAC address entries.
Syntax Description	N/A
Default	N/A
Configuration Mode	Any command mode
History	3.6.2002
History	3.8.1000	Updated example
Example	switch (config) # show mac-address-table summary Number of unicast(local): 4 Number of NVE: 2
Related Commands	mac-address-table static clear mac-address-table
Notes