Overview of MAC Addresses

A MAC address defines the location of a network device. A MAC address consists of 48 bits and is displayed as a 12-digit hexadecimal number. Bits 0 to 23 are assigned by the IETF and other institutions 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: indicates all terminals on a LAN. The broadcast address is all 1s (FF-FF-FF-FF-FF-FF).

• Multicast MAC address: indicates a group of terminals on a LAN. All the MAC addresses with the eighth bit as 1 are multicast MAC addresses (for example, 01-00-00-00-00-00), excluding the broadcast MAC address.