When Stateless Address Autonconfiguration (SLAAC) RFC 4862 is used to create a link-local address based on the interface identifier (Modified EUI-64), before the address is assigned to an interface Duplicate Address Detection (DAD) is processed. Now what happens when DAD fails?
Section 4 just describes that autoconfigurations has to stop:
If a node determines that its tentative link-local address is not unique, autoconfiguration stops and manual configuration of the interface is required.
It is not specified what “manual configuration” means in that context. There are two extensions for DAD (RFC 4429, RFC 7527) which do also not describe what happens when DAD fails.
I would assume that a randomized interface identifier is created and used to create a link-local address e.g. as described in RFC 4941 – Privacy Extensions for Stateless Address Autoconfiguration in IPv6 but i could not find any source or reference specifying such behaviour…
