MAC Address confusion while labbing

AB.Calculus

Working on ICND1 Simulator from Odom Cisco Press, I came across this while labbing on Port Security section:

R1#show int
FastEthernet0/0 is up, line protocol is up
Hardware is MV96340 Ethernet, address is 0200.8888.8888 (bia 0013.197b.1101)

The MAC address are shown, but two different are displayed. I would like to know how can this be?

cpartin

BIA stands for Burned In Address. That's the address that's hard coded into the chip. You can however change the mac address that's actually used for an interface via an IOS command. In this case it was probably done just to make it easier to pick out.

R1(config-if)#do show int fast 0/0
FastEthernet0/0 is administratively down, line protocol is down
  Hardware is Gt96k FE, address is c402.0c10.0000 (bia c402.0c10.0000)
  ....
R1(config-if)#mac-address ?  
  H.H.H  MAC address

R1(config-if)#mac-address 1234.5678.9012
R1(config-if)#do show int fast 0/0
FastEthernet0/0 is administratively down, line protocol is down
  Hardware is Gt96k FE, address is 1234.5678.9012 (bia c402.0c10.0000)