To insure that allocated addresses, by means of manual mechanisms as well as autoconfiguration ones, are unique in a specific link, it is used, before this allocation, the duplicated addresses detection algorithm.

If a duplicated address is detected, this address can be allocated to the interface.

The address to which the duplicated address detection algorithm is being applying to, it is designated as "attempt", until the end of this algorithm.

In this case, it has no consideration that such address has been allocated to an interface, and therefore received packets are discarded.