MAC (Medium Access Control) Address is unique identifier hardware address assigned to Network Interface Card (NIC) of any computing node. All computing nodes need a layer 2 hardware address for transmitting data which happens at Data Link Layer (Layer 2) and Physical Layer (Layer 1) of the OSI layer. When transmitting data on the LAN, the node adds Source MAC address and Destination MAC address to the frame in the Data Link Layer and then sends it to the Physical layer. The physical layer converts the frame into bits and puts in on the physical medium which can be wired or wireless. The MAC address is used in IEEE 802 based Wired and Wireless LAN.
MAC address is 48 bits in length and also referred as MAC 48. EUI-48 has replaced MAC 48. IEEE manages MAC 48 and EUI 48. It consists of two parts, the first 24 bits is Organizationally Unique Identifier (OUI) and next 24 bits is Unique Extension Identifier (UEI). OUI assigns 24 bits identifier for every organization and it’s unique. And each organization assigns 24 bits UEI for Network Interface Card (NIC) that it puts in the computing devices or network devices or servers it manufactures. Thus, every device that has NIC will have unique MAC address
The following are IEEE LAN technologies that used MAC address:
- IEEE 802.3 – Ethernet (Wired)
- IEEE 802.5 – Token Ring (Wired)
- IEEE 802.6 – MAN (Wired)
- IEEE 802.11 – Wi Fi (Wireless)
- IEEE 802.15 – PAN/Bluetooth (Wireless)
- IEEE 802.16 – WIMAX (Wireless)