An Organizationally Unique Identifier (or OUI) is a 24-bit number assigned by the IEEE Registration Authority to a company or organization for use in various computer hardware products, including MAC addresses for Ethernet and other network interface cards and World Wide Names for Fibre Channel host bus adapters.

In MAC addresses, the OUI is combined with an internally-assigned 24-bit number to form the address. The first three octets of the address are the OUI.

See also

• Individual Address Block

External links

• IEEE OUI FAQ
• IEEE OUI and Company_id assignments
• List of registered OUIs

Identifiers | Network addressing

Organizationally Unique Identifier