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Adding and Removing Static Address Entries on Catalyst Switches

June 3, 2008 By Leave a Comment

A static address has these characteristics:

  • It is manually entered in the address table and must be manually removed.
  • It can be a unicast or multicast address.
  • It does not age and is retained when the switch restarts.

You can add and remove static addresses and define the forwarding behavior for them. The forwarding behavior determines how a port that receives a packet forwards it to another port for transmission. Because all ports are associated with at least one VLAN, the switch acquires the VLAN ID for the address from the ports that you specify. You can specify a different list of destination ports for each source port.

A static address in one VLAN must be a static address in other VLANs. A packet with a static address that arrives on a VLAN where it has not been statically entered is flooded to all ports and not learned.

You add a static address to the address table by specifying the destination MAC address (unicast or multicast) and the VLAN from which it is received. Packets received with this destination address are forwarded to the interface specified with the interface-id option.

Beginning in privileged EXEC mode, follow these steps to add a static address:

 

 

Command

Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

mac address-table static mac-addr vlan vlan-id interface interface-id

Add a static address to the MAC address table.

•For mac-addr, specify the destination MAC address (unicast or multicast) to add to the address table. Packets with this destination address received in the specified VLAN are forwarded to the specified interface.

•For vlan-id, specify the VLAN for which the packet with the specified MAC address is received. Valid VLAN IDs are 1 to 4094.

•For interface-id, specify the interface to which the received packet is forwarded. Valid interfaces include physical ports and port channels. For interface-id, specify the interface to which the received packet is forwarded. Valid interfaces include physical ports or port channels. For static multicast addresses, you can enter multiple interface IDs. For static unicast addresses, you can enter only one interface at a time, but you can enter the command multiple times with the same MAC address and VLAN ID.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show mac address-table static

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

 

To remove static entries from the address table, use the no mac address-table static mac-addr vlan vlan-id [interface interface-id] global configuration command.

This example shows how to add the static address c2f3.220a.12f4 to the MAC address table. When a packet is received in VLAN 4 with this MAC address as its destination address, the packets is forwarded to the specified interface:

Switch(config)# mac address-table static c2f3.220a.12f4 vlan 4 interface gigabitethernet0/1

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