Abstract: A fast handover apparatus, method, and medium for performing a fast handover in a wireless LAN environment. The fast handover method includes (a) determining whether a beacon signal input from an access point (AP) to a mobile node (MN) contains border information indicating that the AP is located at the border of its subnet, the AP connecting the MN to a wired network; and (b) selectively performing a handover between subnets based on the determination results obtained in (a). Accordingly, unnecessary communications between an MN and an AR are prevented by providing predetermined information, based on which the MN can determine whether to perform only an L2 handover or both the L2 handover and an L3 handover.