Modified EUI-64

Modified EUI-64 -

EUI-64 (Extended Unique Identifier) is a method we can use to automatically configure IPv6 host addresses. An IPv6 device will use the MAC address of its interface to generate a unique 64-bit interface ID. However, a MAC address is 48 bit and the interface ID is 64 bit. What are we going to do with the missing bits?
IPv6 MAC address vs Interface ID

Here’s what we will do to fill the missing bits:
  1. We take the MAC address and split it into two pieces.
  2. We insert “FFFE” in between the two pieces so that we have a 64 bit value.
  3. We invert the 7th bit of the interface ID.
So if my MAC address would be 1234.5678.ABCD then this is what the interface ID will become:


IPv6 EUI-64 FF FE
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