Patent ID: 7856021

Claim:
A packet transfer method comprising: setting a plurality of partial rate guaranteed services to an available line between a device and an opposed device, each of said partial rate guaranteed services providing a minimum guaranteed transmission rate and a best effort transmission rate; establishing a TCP tunnel between the device and the opposed device of the available line in response to the setting of said partial rate guaranteed services; and encapsulating, when a destination of a packet inputted indicates the opposed device, the packet to be passed through the TCP tunnel, wherein the encapsulating includes selecting such that the IP packet is passed through the minimum guaranteed transmission rate part of the partial rate guaranteed services in the established TCP tunnel when the TOS (Type Of Service) field in a header of the packet indicates a high priority while the packet is passed through the best effort transmission rate part of the partial rate guaranteed services in the established TCP tunnel when the TOS field in a header of the packet indicates a low priority.