Registration Authority

IEEE offers Registration Authority programs or registries which maintain lists of unique identifiers under standards and issue unique identifiers to those wishing to register them. The IEEE Registration Authority assigns unambiguous names to objects in a way which makes the assignment available to interested parties.

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MAC Address Block Large (MA-L)

This product was previously referred to as an OUI (Organizationally Unique Identifier) and is still referred to as such in many standards. OUI is an IEEE Registration Authority (RA) specific term that is referred to in various standards and may be used to identify companies on the IEEE Public Listing. A MA-L assignment includes an OUI and the right to generate various extended identifiers based on that OUI. It is most often used to create IEEE 802-defined MAC addresses (EUI-48 and EUI-64).

The OUI included in the MA-L assignment may be appended with 24 organization-supplied bits to form a EUI-48 or 40 organization-supplied bits to form an EUI-64.

The included OUI may also be used to generate EUI-60 (deprecated), CDI-32, TCDI-40, MAC-48 (obsolete term), create multicast addresses (per IEEE Std 802), and as a unique root for various context dependent identifiers. It may also be used as a company identifier in those protocols and protocol standards that specify the use of a 3 octet field as a part of the protocol identification mechanism.

For more information, please see the tutorial “Guidelines for Use of Organizationally Unique Identifiers (OUI) and Company ID (CID)”.


Registration Fees

ProductsFeesTotal Due
Publicly Registered MA-L
(company name & address on the public listing)
US $2,500US $2,500
Privately Registered MA-L
(company name and address NOT on the public listing)
US $2,500 + $2,890
(privacy fee addition)
US $5,390
Yearly Confidentiality Renewal Fee*
(for privately registered assignments only)
US $2,890 US $2,890
*Effective 5 December 2003, companies requesting confidentiality for OUI assignments are required to pay a fee for privacy. Assignees will also be required to pay an annual fee to maintain confidentiality. Payment options for the renewal fee are credit card, check or wire transfer. IEEE does not accept requests for applicant-specified identifiers.


Application Information
Please search the public listing to determine whether your Organization has already been issued an OUI assignment. If so, you may email us to obtain contact information for the assignment. If a new assignment is required, a Usage Percentage Letter must be submitted.

  1. Complete and submit the MA-L application. Do not submit more than one application unless requesting more than one assignment (see policy regarding obtaining an additional assignment). Applications expire after 30 days.
  2. A tracking number will be sent via email to the REQUESTOR. Any questions regarding your application will be sent via email to the REQUESTOR.
  3. Applications are processed within 7 business days from receipt of payment. Be advised that the credit card will be charged once the application is submitted. Assignment details and a Paid Invoice are sent to the REQUESTOR.
  4. The public MA-L listing is updated once every 24 hours, so new assignments will not be immediately viewable on the directory.


Related Standards
The OUI defined in IEEE 802®-2001 can be used to generate 48-bit Universal LAN MAC addresses to uniquely identify Local and Municipal Area Networks stations, and Protocol Identifiers to identify public and private protocols. These are used in LAN and MAN applications. The relevant standards include but not limited to:

  • CSMA/CD (IEEE 802.3™, ISO 8802-3)
  • Token Bus (IEEE 802.4™, ISO 8802-4)
  • Token Ring (IEEE 802.5™, ISO/IEC 8802-5)
  • IEEE 802.6™ (ISO/IEC DIS 8802-6) FDDI (ISO 9314-2)
  • WLAN (IEEE 802.11™, ISO/IEC 8802-11)

The 'company_id' relevant standards as defined in IEEE 1212™-1991 Control and Status Register (CSR) Architecture referenced by IEEE 896.2™-1991 Futurebus+Physical Layers and Profiles include:

  • IEEE 1596™-1992 Scalable Coherent Interface
  • IEEE 1394™-1995 Serial Bus document. (In this context, the 24-bit company_id value is a portion of the 32-bit Module_Vendor_Id ROM location and related locations, and uniquely identifies hardware vendors and I/O software interface architectures)
  • ANSI X3.230-1994 Fibre Channel Standard

The IEEE Registration Authority will assign an additional OUI to any organization requesting one, providing they submit a letter on company letterhead to the IEEE Registration Authority c/o IEEE Standards Department, stating that their company will not "ship" product in the new block assignment until well after they have reached (shipped) at least 95% of the block assignment, in the context of a specified standard. Your company should ensure that large numbers of derived identifiers are not left unused.