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GUIDELINES FOR USE OF A
48-BIT GLOBAL IDENTIFIER (EUI-48)

General

The IEEE defined 48-bit extended unique identifier (EUI-48) is a concatenation of the 24-bit Organizationally Unique Identifier (OUI) value administered by the IEEE Registration Authority and a 24-bit extension identifier assigned by the organization with that company_id OUI assignment.

The IEEE administers the assignment of 24-bit company_id OUI values. The assignments of these values are public, so that a user of an EUI-48 value can identify the manufacturer that provided any value[1]. The IEEE/RAC has no control over the assignments of 24-bit extension identifiers and assumes no liability for assignments of duplicate EUI-48 identifiers assigned by manufacturers.

Application restrictions

Given the possibility of consuming all the EUI-48 identifiers, the IEEE/RAC places restrictions on their use. For new standards applications, EUI-48 identifiers are restricted to use in low volume applications, such as the identification of software interface standards or hardware model numbers.

While the number of EUI-48 identifiers is large, it is not inexhaustible, and an extended EUI-64 is available. Applications that use the EUI-48 identifier may require special review by the IEEE/RAC. See the UseOfEUI tutorial, MAC-48 identifier restrictions, for details.

The term EUI-48 is trademarked by the IEEE. Companies are allowed to use this term for commercial purposes, but only if their use of this term has been reviewed by the IEEE/RAC and the proposed products using the EUI-48 conform to these restrictions.

Manufacturer-assigned identifiers

The manufacturer identifier assignment allows the assignee to generate approximately 16 million unique EUI-48 values, by varying the last 24 bits. The IEEE intends not to assign another OUI/company_id value to a manufacturer of EUI-48 values until the manufacturer has consumed, in product, the preponderance (more than 90%) of this block of potential unique words. It is incumbent upon the manufacturer to ensure that large portions of the unique word block are not left unused in manufacturing.

48-BIT GLOBAL IDENTIFIER FORMAT TUTORIAL

General

The IEEE defined 48-bit global identifier (EUI-48) is assigned by a manufacturer who has been assigned a company_id OUI value by the IEEE Registration Authority. The 48-bit identifier is a concatenation of the 24-bit company_id OUI value assigned by the IEEE Registration Authority and a 24 bit extension identifier assigned by the organization with that company_id OUI assignment.

The IEEE administers the assignments of 24-bit company_id OUI values. The assignments of these values are public, so that a user of a EUI-48 value can identify the manufacturer that provided any value. The IEEE/RAC has no control over the assignments of 24-bit extension identifiers and assumes no liability for assignments of duplicate EUI-48 identifiers.

Distribution restrictions

The IEEE has no established policies on the redistribution of EUI-48 values or range of values through third parties.

Format

You may have use for a 48-bit global identifier (EUI-48) in new low-volume applications or for implementations of an existing standard that specifies an EUI-48 or equivalent. The 24-bit first portion of this value is the OUI value assigned to the manufacturer by the IEEE Registration Authority. The 24-bit second portion of this identifier is assigned by the manufacturer.

For example, assume that a manufacturer's IEEE-assigned OUI value is AC-DE-48 and the manufacturer-selected extension identifier for a given component is 23-45-67. The EUI-48 value generated from these two numbers is AC-DE-48-23-45-67.

Some standards specify an EUI-48 by a string of six bytes, labeled as eui[0] through eui[5]. For those standards, the format of the EUI-48 is illustrated below. Although different physical standards disagree on the ordering of bit transmissions within bytes, the bytes are normally transmitted in an ascending index-value order.

|            OUI           |   extension identifier   | field 
|                          |                          |
| eui[0] | eui[1] | eui[2] | eui[3] | eui[4] | eui[5] | order
|        |        |        |        |        |        |
|   AC   |   DE   |   48   |   23   |   45   |   67   | hex
 
 10101100 11011110 01001000 00100011 01000101 01100111  bits

Other standards specify an EUI-48 to be a numerical value, upon which computations (such as base/bounds or bit selections) can be performed. For those standards, the format of the EUI-48 is illustrated below:

|            OUI           |   extension identifier   | field 
|                          |                          |
|   AC   |   DE   |   48   |   23   |   45   |   67   | hex

 10101100 11011110 01001000 00100011 01000101 01100111  bits
 
 |  |                                             |  |
 |  most significant byte    least significant byte  |
 |                                                   |
 most significant bit            least significant bit

The byte-address values (addr+0, addr+2, ) in this illustration correspond to the data-transmission order of existing network applications and the memory-addressing order of ISO/IEC 13213 defined memory-mapped identifiers. However, the mapping of the EUI-48 value to sequential data-byte locations is application dependent and could (in theory) be different in new applications.


[1]Except for private company_id OUI values, where the owner of the company_id OUI value is confidential. These shall remain private.

 

 

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Copyright 2003 IEEE

(IEEE Standards Systems/Network Staff)
URL: http://standards.ieee.org/regauth/oui/tutorials/EUI48.html
(Modified: 21-April-2003)

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