To ensure that all configured addresses are likely to be unique on a particular link, nodes run a duplicate address detection algorithm on addresses. The nodes must run the algorithm before assigning the addresses to an interface. The duplicate address detection algorithm is performed on all addresses.
The autoconfiguration process that is specified in this document applies only to hosts and not routers. Because host autoconfiguration uses information that is advertised by routers, routers need to be configured by some other means. However, routers probably generate link-local addresses by using the mechanism that is described in this document. In addition, routers are expected to pass successfully the duplicate address detection procedure on all addresses prior to assigning the address to an interface.