mac address filtering is a form of access control for wireless and wired lans

This bit is also referred to as the UL bit, short for UniversalLocal, which identifies how the address is administered.

This use is common in most IEEE 802 networking technologies, including Ethernet, Wi-Fi, and Bluetooth.

Within the Open Systems Interconnection (OSI) network model, MAC addresses are used in the medium access control protocol sublayer of the data link layer.

As typically represented, MAC addresses are recognizable as six groups of two hexadecimal digits, separated by hyphens, colons, or without a separator.

Each address can be stored in hardware, such as the cards read-only memory, or by a firmware mechanism.

Many network interfaces, however, support changing their MAC address.

MAC addresses are formed according to the principles of two numbering spaces based on Extended Unique Identifiers (EUI) managed by the Institute of Electrical and Electronics Engineers (IEEE): EUI-48, which replaces the obsolete term MAC-48, 1 and EUI-64.

The group bit (b0) distinguishes multicast and unicast addressing and the local or UL bit (b1) distinguishes universal and locally administered addressing.

The IEEE manages allocation of MAC addresses, originally known as MAC-48 and which it now refers to as EUI-48 identifiers.

The IEEE has a target lifetime of 100 years (until 2080) for applications using EUI-48 space and restricts applications accordingly.

The IEEE encourages adoption of the more plentiful EUI-64 for non-Ethernet applications.

MAC-48 was used to address hardware interfaces within existing 802-based networking applications; EUI-48 is now used for 802-based networking and is also used to identify other devices and software, for example Bluetooth.

The IEEE now considers MAC-48 to be an obsolete term.

EUI-48 is now used in all cases.

In addition, the EUI-64 numbering system originally encompassed both MAC-48 and EUI-48 identifiers by a simple translation mechanism.

These translations have since been deprecated.

The IAB uses an OUI from MA-L (MA-L (MAC address block large) registry was previously named OUI registry, the term OUI is still in use, but not for calling a registry 5 ) 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).

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.

Between 2007 and September 2012, the OUI value 00:50:C2 was used for IAB assignments.

The MA-M assignment block provides both 2 20 EUI-48 identifiers and 2 36 EUI-64 identifiers (that means first 28 bits are IEEE assigned bits).

The first 24 bits of the assigned MA-M block are an OUI assigned to IEEE that will not be reassigned, so the MA-M does not include assignment of an OUI.

A universally administered address is uniquely assigned to a device by its manufacturer.

The first three octets (in transmission order) identify the organization that issued the identifier and are known as the organizationally unique identifier (OUI).

The remainder of the address (three octets for EUI-48 or five for EUI-64) are assigned by that organization in nearly any manner they please, subject to the constraint of uniqueness.

A locally administered address is assigned to a device by a network administrator, overriding the burned-in address for physical devices.

Mac Address Filtering Is A Form Of Access Control For Wireless And Wired Lans