The present invention relates to a method in which a mobile node having mobility performs 
handover in a mobile communication 
system, and more particularly, to a 
fast handover method and 
system using network-based localized 
mobility Management. According to an exemplary embodiment of the present invention, in a network access process between a mobile node and a 
base station, the 
base station sends a message allowing network access to the mobile node and a link-up message to an access 
router. Then, the access 
router sends a location registration message, which includes a mobile node identifier, a target 
base station identifier, a localized mobility anchor identifier, and access permission flag information, to a localized mobility anchor (LMA), and receives an 
acknowledgement (Ack) message including network prefix information. Accordingly, when a 
router advertisement (RA) message is sent to the base 
station, the mobile node performs duplicate address detection (DAD). Accordingly, 
fast handover is performed to reduce 
packet loss and 
delay that occur when the mobile node moves between networks, thereby minimizing the 
packet loss and 
delay.