Individual Address Block
The Individual Address Block (IAB) is a block of identifiers that is formed by concatenating a 24-bit Organizationally Unique Identifier (OUI) that is owned by the IEEE Registration Authority with an additional 12-bit extension identifier that is assigned by the IEEE Registration Authority and then reserving an additional 12 bits for use by the assignee. The resulting 48-bit identifier uniquely identifies the assignee of the IAB and provides 4096 unique EUI-48 numbers for use by the organization that purchased the IAB. The assignee may create unique identifiers by concatenating a 12-bit extension identifier that is assigned by the organization that purchases the IAB in the bit positions occupied by the 12 additional bits mentioned previously. The purpose of the IAB is to allow organizations to purchase smaller blocks of identifiers.
The IEEE Registration Authority distinguishes between IABs and OUI-36 values. Both are 36-bit values which may be used to generate EUI-48 values, but IABs may not be used to generate EUI-64 values.
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 value is FF-FF-FF-FF-F0-00 and the 12-bit extension identifier is hhh16, then the EUI-48 value generated by combining these two numbers is FF-FF-FF-FF-Fh-hh.
Note:There are also IAB based CDI-40 sequences that are formed by combining the 36-bit IEEE assigned IAB base value with the 4-bit extension identifier assigned by the organization – e.g., if the IEEE assigned IAB base value is FF-FF-FF-FF-F0-00 and the 4-bit extension identifier is 0h16, then the CDI-40 value generated by combining these two numbers is FF-FF-FF-FF-Fh.
Read more about this topic: Organizationally Unique Identifier
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