Patent ID: 8009629
Filing Date: 2011-08-30
Classification: H04W

Abstract:
1. A communication handover method, which is to be performed when, in a communication system wherein a first access router, which belongs to a first subnet, a second access router, which belongs to a second subnet that is different from the first subnet, and a third access router, which belongs to a third subnet that is different from the first and the second subnets, are connected via an IP network, a mobile terminal, which has a plurality of interfaces and which is connected, via radio communication, to the first subnet using a first interface and is connected to the third subnet using a second interface, switches a connection from the first subnet to the second subnet, comprising the steps of: the mobile terminal transmitting, to the first access router, an FBU, Fast Binding Update, message that includes not only address information to be used on the first subnet but also packet transfer destination address information allocated for the second interface; the first access router transmitting, to the second access router, a packet transfer destination address notification message that includes the packet transfer destination address information that is included in the FBU message; the second access router storing the packet transfer destination address information for the mobile terminal that is included in the packet transfer destination address notification message; the first access router receiving, as a proxy, a packet addressed to the first subnet of the mobile terminal, and encapsulating the packet and transmitting the encapsulated packet to an address to be used on the second subnet of the mobile terminal; the second access router receiving, as a proxy, the encapsulated packet that is transmitted by the first access router to the address to be used on the second subnet of the mobile terminal, and encapsulating the packet and transmitting the encapsulated packet to a packet transfer destination address of the mobile terminal; the mobile terminal receiving, via the second interface, the encapsulated packet that is transmitted by the second access router to the packet transfer destination address of the mobile terminal; when a connection to the second access router using the first interface has been completed, the mobile terminal transmitting a packet transfer halt instruction message to request that packet transfers to the second access router be halted; and upon receiving the packet transfer halt instruction message, the second access router halting encapsulation and transmission to the packet transfer destination address of the mobile terminal.