MAC address table - multiple static entries

The MAC address table is a construct found within switches that corresponds MAC addresses with interfaces on a switch.

It is possible to configure a static MAC address table entry, thus hardwiring a single MAC address to a particular port.

On some platforms, it is possible to assign a static MAC address to multiple ports like so:

SW1(config)#mac address-table static 0000.0000.0001 vlan 1 interface gigabitethernet0/0 gigabitethernet0/1 ?
  GigabitEthernet  GigabitEthernet IEEE 802.3z
  HundredGigE      Hundred Gigabit Ethernet
  Port-channel     Ethernet Channel of interfaces
  TwentyFiveGigE   Twenty Five Gigabit Ethernet
               

SW1(config)#mac address-table static 0000.0000.0001 vlan 1 interface gigabitethernet0/0 gigabitethernet0/1
SW1(config)#

The result is a MAC address table that indicates two or more interfaces that correspond with that MAC address like so:

SW1#show mac address-table 
          Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
   1    0000.0000.0001    STATIC      Gi0/0 Gi0/1 
   1    5254.0006.1a88    DYNAMIC     Gi0/1
Total Mac Addresses for this criterion: 2
SW1#

When this is configured, the last port in the command is the port that is used by the switch to forward frames.

Some platforms, like the 2950 don't allow this configuration, issuing an error message if it is attempted.

Static MAC address entries in the MAC address table should be applied with much care, as misconfigurations can cause problems such as MAC address flapping.

Links:

https://forum.networklessons.com/t/static-mac-address-table-entry/1089/52?u=lagapidis

https://networklessons.com/switching/static-mac-address-table-entry