What do you do with the 7th bit of a MAC address during the EUI-64 conversion process?

During the EUI-64 conversion process, the 7th bit of a MAC address, often referred to as the universal/local (U/L) bit, is inverted. This bit indicates whether the address is universally administered (set to 0) or locally administered (set to 1).

When converting a MAC address to an EUI-64 format for IPv6, this inversion of the 7th bit is a crucial step because it allows the resulting interface identifier to convey whether the address is MAC-based (0) or user-defined (1). By inverting this bit, the conversion process maintains clarity and correctness regarding the allocation of the address, ensuring that it aligns with the standards required for networking and device identification in an IPv6 environment. Thus, this adjustment is essential for the proper representation and functionality of the address within the networking protocol.