Introduction to the MAC Address
A MAC address defines the location of a network device. It consists of 48 bits and is displayed as a 12-digit hexadecimal number. Bits 0 to 23 are assigned by an institution such as the IETF to identify vendors, and bits 24 to 47 are the unique ID assigned by vendors to identify their network adapters.
MAC addresses fall into the following types:
Physical MAC address: uniquely identifies a terminal on an Ethernet network and is the globally unique hardware address.
Broadcast MAC address: used to broadcast a message to all terminals on a LAN. The broadcast address is all 1s (FF-FF-FF-FF-FF-FF).
Multicast MAC address: used to broadcast a message to group of terminals on a LAN. All MAC addresses besides the broadcast MAC address with a 1 as the eighth bit are multicast MAC addresses; for example, 01-00-00-00-00-00. Multicast MAC addresses starting from 01-80-c2 are BPDU MAC address and are often used as the destination MAC address of protocol packets.