Уникальные идентификаторы производителей сетевого оборудования (OUI)

24 bit number in networking equipment that uniquely identifies its manufacturer

An organizationally unique identifier (OUI) is a 24 bit number that uniquely identifies a vendor, manufacturer, or other organization. OUIs are purchased from the Institute of Electrical and Electronics Engineers (IEEE) Registration Authority by the assignee (IEEE term for the vendor, manufacturer, or other organization). Only assignment from MA L registry assigns new OUI. They are used to uniquely identify a particular piece of equipment through derived identifiers such as MAC addresses, Subnetwork Access Protocol protocol identifiers, World Wide Names for Fibre Channel devices or vendor blocks in EDID. In MAC addresses, the OUI is combined with a 24 bit number (assigned by the assignee of the OUI) to form the address. The first three octets of the address are the OUI.

The following terms are defined (either implicitly or explicitly) in IEEE Standard 802 2001 for use in referring to the various representations and formats of OUIs and the identifiers that may be created using them.

“The representation of a sequence of octet values in which the values of the individual octets are displayed in order from left to right, with each octet value represented as a two digit hexadecimal numeral, and with the resulting pairs of hexadecimal digits separated by hyphens. The order of the hexadecimal digits in each pair, and the mapping between the hexadecimal digits and the bits of the octet value, are derived by interpreting the bits of the octet value as a binary numeral using the normal mathematical rules for digit significance.”

The CDI 32 was historically recommended as context dependent identifier that was formed by concatenating the 24 bit OUI with an 8 bit extension identifier that is assigned by the organization that purchased the OUI – the resulting identifier was generally represented as a set of octets separated by dashes (hexadecimal notation) or colons (bit reversed notation) as in FF FF FF FF or FF:FF:FF:FF, as a string of 4 bytes as in {FF,FF,FF,FF}, or as a base 16 number as in FFFFFFFF16. There are other identifiers that may be formed using the OUI but those listed above are the most commonly used.

Mapping an EUI 48 to an EUI 64 is deprecated. The mapping is described here for historical reasons. Other identifiers, such as MAC 48 and EUI 48 values, can be contained within a larger identifier or 'container', such as EUI 64, by creating the larger identifier through a process of combining the smaller identifier with specified values placed in specified bit positions within the larger identifier – this process is known as 'encapsulation' and is provided for the purpose of easing the transition from MAC 48 and EUI 48 to EUI 64 and to provide a mechanism for the conversion of MAC 48 and EUI 48 identifiers to EUI 64 in such a way that duplicate or conflicting values are avoided. and SAS, and is also supported in iSCSI in RFC 3980. This addition requires either a shortened vendor specific identifier field, or some OUI bits are assumed to be 0, such as when using EUI 64 Mapped format.

An Individual Address Block (IAB) is an inactive registry activity which has been replaced by the MA S registry product as of 1 January 2014. The IAB uses a MA L (and OUI) belonging to the IEEE Registration Authority, concatenated with 12 additional IEEE provided bits (for a total of 36 bits), leaving only 12 bits for the IAB owner to assign to their (up to 4096) individual devices. An IAB is ideal for organizations requiring not more than 4096 unique 48 bit numbers (EUI 48). Unlike an OUI, which allows the assignee to assign values in various different number spaces (for example, EUI 48, EUI 64, and the various context dependent identifier number spaces), the Individual Address Block could only be used to assign EUI 48 identifiers. All other potential uses based on the OUI from which the IABs are allocated are reserved, and remain the property of the IEEE Registration Authority. It should also be noted that, between 2007 and September 2012, the OUI value 00:50:C2 was used for IAB assignments. After September 2012, the value 40:D8:55 was used. The owners of an already assigned IAB may continue to use the assignment. The OUI 36 is a deprecated registry activity name, which has been replaced by the MA S registry product name as of 1 January 2014. This registry activity includes both a 36 bit unique number used in some standards and the assignment of a block of EUI 48 and EUI 64 identifiers (while owner of IAB cannot assign EUI 64) by the IEEE Registration Authority. The owner of an already assigned OUI 36 registry product may continue to use the assignment. Example of EUI 48 created within an IAB: An EUI 48 identifier is formed by combining the 36 bit IEEE assigned IAB base value with a 12 bit extension identifier assigned by the organization – e. g., if the IEEE assigned IAB base 16 value is 0x0050C257A and the 12 bit extension identifier is 0xFFF, then the EUI 48 value generated by combining these two numbers is 0x0050C257AFFF.