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Difficulty: MediumIPv6 Address Types and EUI-64

A network switch interface has a burned-in MAC address of `3464.a912.3456`. When calculating an IPv6 address using the standard IEEE EUI-64 process, what is the generated 64-bit interface identifier expressed in standard colon-separated IPv6 hexadecimal notation?

Answer: 3664:a9ff:fe12:3456 / 3664:A9FF:FE12:3456

Answer

3664:a9ff:fe12:3456
Converting the MAC address 34-64-A9-12-34-56 to EUI-64 format requires inserting FFFE into the middle (34-64-A9-FF-FE-12-34-56) and inverting the 7th bit of the first byte (0x34 becomes 0x36). Grouping into 16-bit hexadecimal blocks separated by colons yields 3664:a9ff:fe12:3456.

Step-by-Step Solution

1
Split the 48-bit MAC address into two 24-bit halves.
Left half: 34:64:A9, Right half: 12:34:56.
EUI-64 requires inserting a specific 16-bit hexadecimal value into the midpoint of the MAC address.
2
Insert the hexadecimal value FFFE between the two halves.
34-64-A9-FF-FE-12-34-56
IEEE EUI-64 standard specifies the insertion of FFFE to expand a 48-bit MAC address to 64 bits.
3
Invert the 7th bit (Universal/Local bit) of the first byte (0x34).
Binary 0x34 = 0011 0100; inverted 7th bit = 0011 0110 = 0x36. The updated byte sequence is 36-64-A9-FF-FE-12-34-56.
The Universal/Local (U/L) bit is flipped to indicate a globally unique, modified EUI-64 address.
4
Format the resulting 64-bit value into IPv6 colon-separated hexadecimal quads.
3664:a9ff:fe12:3456
IPv6 interface identifiers are written as four 16-bit hexadecimal blocks separated by colons.

Key Concept

EUI-64 Interface Identifier Derivation
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Topics

IPv6 Address Types and EUI-64

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