5.4.5 When Duplicate Address Detection Fails
A tentative address that is determined to be a duplicate as described
above MUST NOT be assigned to an interface and the node SHOULD log a
system management error. If the address is a link-local address
formed from an interface identifier based on the hardware address
(e.g., EUI-64), the interface SHOULD be disabled. In this case, the
IP address duplication probably means duplicate hardware addresses
are in use, and trying to recover from it by configuring another IP
address will not result in a usable network. In fact, it probably
makes things worse by creating problems that are harder to diagnose
than just shutting down the interface; the user will see a partially
working network where some things work, and other things will not. On
the other hand, if the duplicated link-local address is not formed
from an interface identifier based on the hardware address, the
interface MAY continue to be used.
