Skip navigation
Electronic Design
Numbers for Sale: A Different Kind of Standard

Numbers for Sale: A Different Kind of Standard

Networked devices make the world go ‘round (…and you thought it was love). Millions of devices connected to each other via standards such as Ethernet and Wi-Fi drive modern communication. But there’s more to the network than just devices and standards. Each device, in order to communicate with the rest, must have its own unique designation. This designation is known as a Media Access Control Address, or MAC address. Your laptop has a MAC address, as does your smartphone, and every server in a data center. The MAC address, built into the device’s network card, isn’t of any concern for most people.

When you look deeper, though, MAC addresses can be quite interesting. Start with this: Imagine if all manufacturers made up their own addresses for each individual network card and simply hoped that other manufacturers wouldn’t use the same ones. The result would be a chaotic mess of numbers and characters arranged in countless formats. Devices would be completely unable to identify each other, making any type of network impossible.

There must be a standard to bring order to the chaos. This is a different kind of standard than a file format or API, such as the standards used for electronic design, but it’s no less critical for building networkable electronic products. All manufacturers use an existing standard numbering scheme to uniquely identify each network card they produce.

If you assume that some higher authority passes out the address numbers and oversees this process to minimize errors and cheating, then you are correct. That higher authority, which manages the standard and distributes numbers, is called a Registration Authority. You might be surprised to learn that the IEEE Standards Association is responsible for assigning MAC addresses through its IEEE-SA Registration Authority Committee (RAC).

Simply defined, a Registration Authority is an agency that’s responsible for issuing, controlling, and maintaining lists of codes under international standards. In a broad sense, authority control keeps society organized. We live with a wide variety of registration authorities, such as International Standard Book Numbers (ISBNs), social-security numbers, motor vehicle registration, telephone numbers, Universal Product Codes (UPCs), and passport numbers. Each allows for unique identification of an object, location, or person by virtue of some type of code.

Download this article in .PDF format
This file type includes high resolution graphics and schematics when applicable.

For objects, the code can be an Object Identifier (OID). The specific definition of the OID standard comes from the joint efforts of the International Organization for Standardization (ISO), International Electrotechnical Commission (IEC), and International Telecommunication Union (ITU-T), and is known as ASN.1.

For MAC addresses of network cards, the OID comes in the form of an Organizationally Unique Identifier (OUI) plus a Company Identifier (CID). The OUI represents the manufacturer, and the CID is the serial number of the network card. MAC address formats comprise six octets (hexadecimal)—three for the OUI and three for the CID. In human-readable form, it looks like:


OUIs obtained from the IEEE Standards Association can be used for other networked device addresses in addition to MAC addresses. As examples, Xerox was assigned the OUI, 00-00-00, and Hitachi was assigned FC-FE-77. The list of OUIs, maintained by the IEEE-SA’s Registration Authority Committee, is updated daily on its public website. Vendors can opt to make their OUIs private, so finding out who owns the MAC address of your device could be futile.

To be effective, the IEEE-SA’s Registration Authority—or any Registration Authority for that matter—it must meet certain requirements. First and foremost, the Authority must be widely accepted as a trusted authority. It has to be meticulous in its processes, controls, and maintenance. In addition, excellent customer service and long-term continuity is mandatory.

Because a Registration Authority needs funding to ensure continued, quality operations, it sells the numbers it assigns. The price can’t be too high, though. In fact, it should be sufficiently inexpensive so that it’s attractive to everyone, and to discourage cheating or a black market. Finally, because an ever-increasing number of devices are being manufactured and sold, a Registration Authority must never run out of numbers for sale!

The IEEE-SA’s Registration Authority Committee reports to the IEEE Standards Association’s Board of Governors, the highest governance body of the IEEE Standards Association. The RAC consists of up to 21 volunteer members (although usually less than 10), along with at least one member of the IEEE-SA’s professional staff. The RAC is responsible for assigning, reporting, and maintaining its international OUI registry. It also administers other types of unique identifiers beyond the scope of this article. RAC members are dedicated experts who understand not only the technical requirements of the OID standard, but also the market conditions at play in an ever-evolving world of networks and devices.

If you are one of the special individuals that find this kind of standard fascinating, there is a Registration Authority, such as IEEE’s RAC, waiting for you to join, helping ensure order and effectiveness in the critical field of networking.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.