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GUIDELINES FOR
64-BIT GLOBAL IDENTIFIER (EUI-64)
REGISTRATION AUTHORITY

General

The IEEE defined 64-bit extended unique identifier (EUI-64) is a concatenation of the 24-bit OUI value by the IEEE Registration Authority and a 40-bit extension identifier assigned by the organization with that OUI assignment.

The IEEE administers the assignment of 24-bit OUI values. The assignments of these values are public, so that a user of an EUI-64 value can identify the manufacturer that provided any value[1]. The IEEE Registration Authority Committee (IEEE/RAC) has no control over the assignments of 40-bit extension identifiers and assumes no liability for assignments of duplicate EUI-64 identifiers assigned by manufacturers.

Application restrictions

Given the minimal probability of consuming all the EUI-64 identifiers, the IEEE/RAC places minimal restrictions on their use within standards. They may be used to identify protocols or options defined within a standard, or to distinctively identify hardware instances of devices. However, they may not be use to identify objects generated by a hardware instance, including the following:

  1. Transactions or other software generated identifiers.
  2. Sequence numbers use to distinctively identify power or reboot cycle instances.
  3. Extensions of hardware functionality to multiple virtual instances.

Note that EUI-64 identifiers, when concatenated with a disk/system managed 64-bit identifier, may be used to create distinct 128-bit (or larger) unique object and/or file identifiers, and such use is not discouraged.

If used within the context of an IEEE standard, the documentation shall must be reviewed by the IEEE/RAC for correctness and clarity. The IEEE/RAC does not restrict the use of EUI-64 identifiers within standards, based on the perceived value of the application, if the standard conforms to the aforementioned restrictions. If the EUI-64 is referenced within non-IEEE standards, there shall not be any reference to IEEE unless approved by the IEEE/RAC .

Distribution restrictions

Given the minimal probability of consuming all the EUI-64 identifiers, the IEEE/RAC places minimal restrictions on their redistribution through third parties, as follows:

  1. Allocation. The EUI-64 values shall can only be sold within electronically readable parts; no more than one EUI-64 value shall can be contained within each component sold for the purpose of redistributing EUI values. (Inclusive products, such as network and/or I/O cards, have no number-of-EUIs restriction and may utilize multiple EUI-64 values to identify each of multiple supported protocols, formats, or features.)
  2. Packaging. A component containing the EUI-64 value shall must have a distinguishing characteristic (such as color or shape) to distinguish it from other commonly used identifier components.
  3. Documentation. Readily available documentation (see following page).
  4. Legal indemnification. Any organization producing EUI-64 values shall must indemnify the IEEE for damages arising from duplicate number assignments.

The term EUI-64 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-64 conform to these restrictions.

Application documentation

As a condition for receiving an OUI assignment, a manufacturer of EUI-64 values accepts the following responsibilities:

  1. This documentation shall must be readily available (at no cost) to any purchaser of EUI-64 values.
  2. The manufacturer's part specification should include an unambiguous description of how the EUI-64 value is accessed (pin and/or address descriptions).

Manufacturer-assigned identifiers

The manufacturer identifier assignment allows the assignee to generate approximately 1 trillion (1012) unique EUI-64 values, by varying the last 40 bits. The IEEE intends not to assign another OUI value to a manufacturer of EUI-64 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.

64-BIT GLOBAL IDENTIFIER FORMAT TUTORIAL

General

The IEEE defined 64-bit global identifier (EUI-64) is assigned by a manufacturer who has been assigned an OUI value by the IEEE Registration Authority. The 64-bit identifier is a concatenation of the 24-bit OUI value assigned by the IEEE Registration Authority and a 40 bit extension identifier assigned by the organization with that OUI assignment.

The IEEE administers the assignments of 24-bit OUI values. The assignments of these values are public, so that a user of an EUI-64 value can identify the manufacturer that provided any value. The IEEE/RAC has no control over the assignments of 40-bit extension identifiers and assumes no liability for assignments of duplicate EUI-64 identifiers.

Format

You may have a 64-bit global identifier (EUI-64) provided by an authorized manufacturer of these values (in the form of electronically readable chips). A 24-bit first portion of this value is the OUI value assigned to the manufacturer by the IEEE Registration Authority. A 40-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-AB-CD. The EUI-64 value generated from these two numbers is AC-DE-48-23-45-67-AB-CD.

Some standards specify an EUI-64 by a string of eight bytes, labeled as eui[0] through eui[7]. For those standards, the format of the EUI-64 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] | eui[6] | eui[7] | order
|        |        |        |        |        |        |        |        |
|   AC   |   DE   |   48   |   23   |   45   |   67   |   AB   |   CD   | hex
 
 10101100 11011110 01001000 00100011 01000101 01100111 10101011 11001101  bits

Other standards specify an EUI-64 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-64 is illustrated below:

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

 10101100 11011110 01001000 00100011 01000101 01100111 10101011 11001101  bits
 
 |  |                                                               |  |
 |  most significant byte                      least significant byte  |
 |                                                                     |
 most significant bit                              least significant bit

If provided in byte-addressable media, the data bytes eui[0] through eui[7] should correspond to the lowest through highest byte addresses.

When transferred to other electronically readable locations (within a disk file or network packet, for example) the relative ordering of the bytes may be changed, as specified within the applicable standard.

Restricted encapsulated values

To support encapsulation of EUI-48 and MAC-48 values within small subsets of the EUI-64 values, the first two bytes of the manufacturer's extension identifier shall must not be FF-FF or FF-FE. Thus, the 64-bit values of the following form are never assigned EUI-64 values:

   XX-XX-XX-FF-FE-YY-YY-YY   (an EUI-48 extension)

   XX-XX-XX-FF-FF-YY-YY-YY   (a MAC-48 extension)

The letters 'X' and 'Y' represent hexadecimal digits and show how the EUI-48 value can be unambiguously encapsulated within the EUI-64 value; the 'X' and 'Y' digits represent the OUI and extension-identifier portions of the EUI-48/MAC-48 values, respectively.

This allows MAC-48 and EUI-48 identifiers to be encapsulated and transported as (otherwise unassigned) EUI-64 identifiers. The intent is to enable migration to a single form of OUI based globally unique 64-bit identifiers.

Encapsulated EUI-48 values

An EUI-48 identifier can be encapsulated and placed within an EUI-64 container. For example, assume that a manufacturer's IEEE-assigned OUI value is AC-DE-48 and the manufacturer-selected extension identifier for a given item is 23-45-67. The EUI-48 value generated from these two numbers is AC-DE-48-23-45-67, whose byte and bit representations are illustrated below:

|            OUI           |   extension identifier   | field 
|                          |                          |
|   AC   |   DE   |   48   |   23   |   45   |   67   | hex
 
 10101100 11011110 01001000 00100011 01000101 01100111  bits

An EUI-64 value is generated by concatenating OUI, FF-FE, and extension-identifier values. The byte and bit representations for this EUI-64 value are illustrated below:

|            OUI           |    EUI label    |   extension identifier   | field 
|                          |                 |                          |
|   AC   |   DE   |   48   |   FF   |   FE   |   23   |   45   |   67   | hex
 
 10101100 11011110 01001000 11111111 11111110 00100011 01000101 01100111  bits

Encapsulated MAC-48 values

A MAC-48 identifier can be encapsulated and placed within an EUI-64 container. For example, assume that a manufacturer's IEEE-assigned OUI value is AC-DE-48 and the manufacturer-selected extension identifier for a given item is 01-23-45. The EUI-48 value generated from these two numbers is AC-DE-48-01-23-45, whose byte and bit representations are illustrated below:

|            OUI           |   extension identifier   | field 
|                          |                          |
|   AC   |   DE   |   48   |   01   |   23   |   45   | hex
 
 10101100 11011110 01001000 00000001 00100011 01000101   bits

An EUI-64 value is generated by concatenating OUI, FF-FE, and extension-identifier values. The byte and bit representations for this EUI-64 value are illustrated below:

|            OUI           |    EUI label    |   extension identifier   | field 
|                          |                 |                          |
|   AC   |   DE   |   48   |   FF   |   FF   |   01   |   23   |   45   | hex
 
 10101100 11011110 01001000 11111111 1111111F 00000001 00100011 01000101  bits

Unassigned EUI-64 values

The all-zeros and all-ones EUI-64 values will never be assigned and may be used to represent NULL EUI-64 address values. As an example, either of these values could represent an uninitialized value, before that location is accessible or properly initialized by hardware/firmware. Similarly, either value could represent invalid, when an optional EUI-64 value not supplied.


[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/EUI64.html
(Modified: 21-April-2003)

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