What is EUI-64?
EUI-64, short for Extended Unique Identifier 64-bit, is a format used to create a unique identifier for network devices, particularly in Ethernet-based networks. It is an extension of the 48-bit MAC (Media Access Control) address that is used to uniquely identify network interfaces. EUI-64 provides a way to expand the address space and increase the uniqueness of identifiers.
Overview of EUI-64 Format
In the EUI-64 format, the original MAC address is extended to a 64-bit value by inserting a 16-bit value in the middle. This process ensures that the resulting address is unique within a given network. The 16-bit value inserted in the middle is typically the hexadecimal value “FFFE”.
To create the EUI-64 address, the universal/local bit of the original MAC address is inverted. The universal/local bit determines whether the address is universally administered or locally administered. A universally administered address is assigned by the IEEE (Institute of Electrical and Electronics Engineers), while a locally administered address is assigned by the network administrator.
For a universally administered address, the seventh bit of the original MAC address is flipped. This ensures that the resulting EUI-64 address is also universally administered. On the other hand, for a locally administered address, the seventh bit remains unchanged.
Usage of EUI-64
One of the main applications of EUI-64 is in the configuration of IPv6 addresses. In IPv6, EUI-64 addresses are often used to automatically assign unique addresses to network interfaces. By combining the EUI-64 address with a network prefix, a unique IPv6 address can be generated.
Moreover, EUI-64 addresses are also used in other network protocols, such as Bluetooth and Zigbee, to create unique identifiers for devices.
In conclusion, EUI-64 is a format used to extend a 48-bit MAC address to a 64-bit value, providing a unique identifier for network devices. It is commonly used in IPv6 configurations and other network protocols. With its ability to increase the uniqueness of identifiers, EUI-64 plays a crucial role in ensuring proper identification and address assignment in modern networks.
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