MAC Addresses

By Joshua Erdman
Digital Foundation, inc.

MAC Address

A MAC address (Media Access Control) is a unique address given to each network host (this includes computers, PLCs - prorammable logic controllers, routers, and wireless devices. This does not include hubs and switches that are not managable). In other words anything that you can browse, telnet, e-mail, FTP, or otherwise connect to using an ethernet network has a MAC address.

MAC Address Format

How each address is guaranteed unique is how they are formatted. The first half of the address is assigned to the manufacturer. If a manufacturer uses all the available addresses, they must apply for another address assignment. The rest of the address is determined by the manufacturer. Some may format parts of the address to match each different product.

MAC Addresses and Network Layers

The MAC address is at the second layer of the OSI network model, called the link layer. The first layer is the physical layer, this includes all the wires and devices that make up the network. Read our article on the 7 layer OSI model to learn more information.

References:
7 Layer OSI Model

TCP/IP Addresses

Counting in Binary

Article last reviewed: 05/02/2004

Created by: Digital Foundation, inc.

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