EUI-64

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As EUI-64 ( 64-bit Extended Unique Identifier ) refers to a the IEEE standardized MAC address format for identifying network devices. An EUI-64 address is 64 bits long and consists of two parts:

  • The first 24, 28 or 36 bits identify the hardware manufacturer (see OUI ).
  • The remaining bits are used for device identification.

A variant of this is the so-called modified EUI-64 address format, which is used with IPv6 . This differs in that the value of the seventh bit (from the left) of an EUI-64 address, also known as the universal / local bit , is inverted.

conversion

A 48-bit MAC address can also be converted into the modified EUI-64 address format. To do this, proceed as follows:

  1. The MAC address is divided into two 24-bit long parts, with the first part forming the first 24 bits and the second part forming the last 24 bits of the modified EUI-64 address.
  2. The remaining 16 bits, which are in the middle of the EUI-64 address to be formed, are assigned according to the following bit pattern: 1111 1111 1111 1110 (hexadecimal: FFFE ).
  3. After step two, the address is in EUI-64 format. If you now invert the value of the seventh bit from the left as mentioned above , you get the modified EUI-64 address.

The conversion of a MAC address into the EUI-48 format has been declared obsolete by the IEEE because there is a risk of overlapping.

literature

  • Christoph Meinel, Harald Sack: Internetworking: Technical Basics and Applications. Springer, Heidelberg 2012.

Web links

Individual evidence

  1. ↑ Guidelines for 48-Bit Global Identifier (EUI-48) ( English ) IEEE Standards Association. Archived from the original on June 20, 2017. Retrieved March 18, 2019.