What is an Individual Address Block (IAB)?

The Individual Address Block is an inactive registry activity, which was replaced by the MA-S registry product as of January 1, 2014. The owner of a previously assigned IAB may continue to use the assignment until its exhaustion. The IAB was used by organizations and companies that required less than 4097 unique 48-bit numbers (EUI‌-48) and thus found little sense in buying their own OUI. The IAB uses a MA-L (and OUI) belonging to the IEEE Registration Authority, linked with 12 additional IEEE-provided bits (for a total of 36 bits), leaving only 12 bits for the IAB owner to assign to their individual devices (up to 4096). Unlike an OUI, which allows assigning values in various different number spaces (for example, EUI‌-48, EUI‌-64, and the various CDI 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 was changed to 40:D8:55. Applications using EUI‌-48 values assigned under an IAB should have made no assumptions about the bit pattern present in the (24-bit most-significant) OUI portion of the assigned numbers.