ACCESS SERVICE NETWORK SYSTEM, ACCESS DEVICE, L2TP TUNNEL LINE CONCENTRATOR AND HOME AGENT, AND ACCESS SERVICE PROVIDING METHOD

摘要

An access service network system establishes a communication connection between a terminal (11) and ISP networks (10a to 10c) by using a communication connection L2TP in an access service network that accommodates the terminal (11) and includes plural LACs (2a, 2b) that tunnel layer 2 data, LNSs (3a, 3b) that terminate the tunnel and the layer 2 data; and a home agent (4)'. When the terminal (11) accesses the LNS (3a), the LAC (2a) generates for each terminal (11) a virtual access instance (20a) which generates an L2TP tunnel between the LAC (2a) and the LNS (3a). When the terminal (11) moves to the other LAC (2b), the LAC (2a) moves a virtual access instance (20b) to the LAC (2b) at the move destination. The home agent (4) transmits a message destined to the virtual access instance, using a Mobile IP.