What is a MAC Address


A Media Access Control or MAC address, is a unique hardware identification tag built into every networkable device. It is used primarily to identify a device among others on a network as its tag is unique to the device but is also used in the MAC sub-layer of Layer 2 in the OSI model (the Data Link layer) to move data packets from one network interface card (NIC) to another. This ensures signals sent from different nodes across the network do not collide. As the MAC address is hardwired into the device during production it cannot be changed. MAC addresses use the same Hexadecimal characters as IPv6 addresses, although its format is much different with each address comprising of 6 – 2 character sets, separated by colons.

MAC Address Format:* **XX:XX:XX:XX:XX:XX**

Upon looking at a MAC address, it may seem completely random, however, each MAC address has a particular arrangement of characters which can be interpreted. The easiest way to read a MAC address is to split it in half. By doing this, each half of the MAC address is now comprised of three 2 character sets. (**XX:XX:XX**).

Now to analyse each half. The first half of any MAC address is referred to as the OUI, or Organisational Unique Identifier; this arrangement of characters are unique to a particular manufacturer and can be used to identify the manufacturer simply by looking at these characters.

The second half of the MAC address (the last three 2 character sets) is referred to as the EUI or Extended Unique Identifier. These characters may also appear to be random, however, in relation to Brainboxes they are a logical value.

As a manufacturer we are assigned a range of MAC address values, these vary from manufacturer to manufacturer. When a product is built, a MAC address is taken from a list of addresses that we have been assigned and hardwired into the device. The address is then removed from the list as to ensure it cannot be set onto another device by mistake, this is how we assign a MAC address, although the method may and often is different between manufacturers.

For Reference: The Brainboxes Organisational Unique Identifier characters are: 00:0A:4F.