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 a 24-bit Organizationally Unique Identifier (OUI) value administered  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 the value[1]. The IEEE 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. Their major use is to distinctively identify hardware instances of devices.

They may also be used for other purposes where a unique identifier is desired. However, they may not be used to identify autonomously generated objects such as:

1.      Transaction  identifiers or other ephemeral identifiers.

2.      Sequence numbers that distinctively identify power or reboot cycle instances.

However, EUI-64 identifiers could be concatenated with a  locally managed 64-bit identifier to create distinct 128-bit (or larger) unique object or file identifiers. Such use is not discouraged.

The IEEE/RAC reviews draft IEEE standards for correctness and clarity of EUI-64 usage. The IEEE/RAC does not restrict the use of EUI-64 identifiers within standards, 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. The main purpose of IEEE/RAC review is to ensure sufficiently efficient usage of assigned address spaces.

Usage restrictions

The EUI-64 is a trademarked IEEE term and there are a number of restrictions on EUI-64 usage; see  <<application form>> for details. These restrictions are subject to change on a per-purchase basis.

Application documentation

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

1.      This documentation  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. It is incumbent upon the manufacturer to ensure that large portions of the block are not left unused in the consumption process.

64-BIT GLOBAL IDENTIFIER FORMAT TUTORIAL

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 here as eui[0] through eui[7]. For those standards, the format of the EUI-64 is illustrated below. Although different  standards may specify different bit-transmission orders, 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

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

|            OUI           |   extension identifier   | field

|                          |                          |

|   AC   |   DE   |   48   |   23   |   45   |   67   | hex

|            OUI           |    EUI label    |   extension identifier   | field 

|                          |                 |                          |

|   AC   |   DE   |   48   |   FF   |   FE   |   23   |   45   |   67   | hex

|            OUI           |   extension identifier   | field 

|                          |                          |

|   AC   |   DE   |   48   |   01   |   23   |   45   | hex

|            OUI           |    EUI label    |   extension identifier   | field 

|                          |                 |                          |

|   AC   |   DE   |   48   |   FF   |   FF   |   01   |   23   |   45   | hex