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Guidelines for use of a
48-bit Extended Unique Identifier (EUI-48™)
General
The IEEE defined 48-bit extended unique identifier (EUI-48™) is a concatenation of either a 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 OUI assignment, or the concatenation of a 36-bit Individual Address Block (IAB) identifier /or 36-bit Organizationally Unique Identifier (OUI-36)/, and a 12-bit extension identifier assigned by the organization with that IAB assignment.
The IEEE administers the assignment of 24-bit OUI values and 36-bit OUI-36/IAB identifiers. The assignments of these values are public, so that a user of an EUI-48 value can identify the manufacturer that provided the value h[1]. The IEEE/RAC has no control over the assignments of 24-bit or 12-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 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 Use Of EUI 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 of an OUI to generate approximately 16 million unique EUI-48 values, by varying the last 24 bits, and allows the assignee of an OUI-36/IAB to generate 4096 unique EUI-48 values, by varying the last 12 bits. The IEEE intends not to assign another OUI or OUI-36/IAB value to a manufacturer of EUI-48 values until the manufacturer has consumed, in product, the preponderance (more than 90%) of the previously assigned block. It is incumbent upon the manufacturer to ensure that large portions of the block are not left unused in manufacturing.
48-BIT EXTENDED UNIQUE IDENTIFIER FORMAT TUTORIAL
General
The IEEE defined 48-bit global identifier (EUI-48) is assigned by a manufacturer who has been assigned an OUI or OUI-36/IAB value by the IEEE Registration Authority. The 48-bit identifier is a concatenation of a 24-bit OUI value assigned by the IEEE Registration Authority and a 24 bit extension identifier assigned by the organization with that OUI assignment, or a concatenation of a 36-bit OUI-36/IAB identifier assigned by the IEEE Registration Authority and a 12 bit extension identifier assigned by the organization with that OUI-36/IAB assignment.
The IEEE administers the assignments of 24-bit OUI values and 36-bit OUI-36/IAB identifiers. The assignments of these values are public, so that a user of a EUI-48 value can identify the manufacturer that provided the value. The IEEE 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.
OUI based identifier sequence
An OUI based 48-bit global identifier (EUI-48) consists of two portions. 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 here as eui[0] through eui[5]. For those standards, the format of the EUI-48 is illustrated below. Although different standards may specify different bit-transmission orders, bytes are normally transmitted in an ascending index-value order.
Value: AC-DE-48-23-45-67
| OUI | extension identifier | field
| | |
| eui[0] | eui[1] | eui[2] | eui[3] | eui[4] | eui[5] | order
| | | | | | |
| AC | DE | 48 | 23 | 45 | 67 | byte
IAB based identifiers