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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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