The MAC address is broken into :
Network Interface Controller Specific (NIC)
24-bits long.
Uniquely identifies interface (card, chip, etc.)
/sbin/ifconfig
The MAC protocol is used by Ethernet, Bluetooth, Modern Token-ring, Wireless, etc. and most other devices following the IEEE 802 protocol.
Services/protocols :
Adress Resolution Protocol (ARP) - converts network address (IP) to a MAC address - port 802
Reverse Adress Resolution Protocol (RARP) - converts MAC address to a network address (IP)
BOOTP - combines both. Superceeded ARP/RARP
67-server, 68-client DHCP - dynamic host configuration protocol. Performs both ARP and RARP.
ARP/RARP and Bootp had to run on a system on the same local network as the requesting system.
DHCP can run at a single centeralized location and service several local sub-nets.
Most modern DHCP servers will handle the older ARP/RARP and Bootp ports.