EUI-64

EUI-64 or Modified EUI-64 are often used as the lower 64 bit of a IPv6 Address.

EUI-64

EUI-64 or Extended Unique Identifier is a 64 bit Global Identifier administered by IEEE

Examples of use

FireWire and in IPv6 as least significant 64 bits in Link-Local and Global Unicast if Stateless Autoconfiguration. (Except Systems that will choice a Random page fx. Windows 7)

EUI-48

EUI-48 or Extended Unique Identifier is a 48 bit Global Identifier administered by IEEE.

Examples of use

Ethernet MAC addresses is a example of EUI-48 usage. Other examples of technologies that use EUI-48 are Bluetooth and 802.11 Wireless Networks.

IPv6 Modifed EUI-64 Address

Understanding the MAC-Address The MAC-Address is divided into two parts. The first 24 bits identifies the manufacturer and are called the OUI The OUI is administered by IEEE The last 24 bits identifies Extension Identifier or NIC The manufacturer can use this field as serial-number The MAC-Address is Global Unique and has two flag in its first octet. (Byte) bit 1: Unicast or Multicast The MAC 'broadcast' address FF:FF:FF:FF:FF:FF is really a Well-Known link-local Multicast address used by for example IPv4 ARP and DHCP. bit 2: Globally or locally administered. When bit 2 is 0 the Global Unique IEEE identifier is used. When bit 2 is 1 it's a Local generated address.

Generating the Modified EUI-64 When generating a modified EUI-64 as the 64 lower bits of a IPv6 Address the hosts EUI-48 (MAC-Address) is expanded to 64 bits by inserting FF:FE between the OUI and the Extension Identifer or NIC and setting the Locally Administered Bit. Example A node with MAC-address 00:10:56:A7:16:D5 will generate 00:10:56:FF:FE:A7:16:D5 as EUI-64