Patent ID: 7430205

Claim:
A packet transfer apparatus for serving a plurality of communication terminals having IP addresses and for connecting the communication terminals through a Layer 2 Tunneling Protocol (L2TP) network to the Internet, the packet transfer apparatus comprising: a protocol processing block for specifying a priority policy for associating a priority level with a path selection method and for selecting one of a plurality of physical paths formed by a plurality of routers in the L2TP network; a plurality of channel interfaces for transferring a received packet to the protocol processing block and for sending the packet received from the protocol processing block in a communication protocol used on an input/output channel; a switch for transferring the packet received from the protocol processing block to another protocol processing block connected to the channel interface containing an output port having a given address; a user information table for specifying a destination address of an L2TP tunnel and an L2TP session, a flow threshold level, and a priority level, in correspondence with a user ID of a user using a communication terminal; and a path management table for storing a path identifier of each path to a destination subnet address, addresses of routers included in each path, and a metric value representing the proximity to a destination subnet or the transfer rate of each path; wherein the protocol processing block creates a user management table storing the destination addresses of the L2TP tunnels and the L2TP sessions, the flow threshold levels, and the priority levels of the users defined in the user information table, in correspondence with identifiers for identifying the individual users, when the L2TP tunnel and the L2TP session are established; detects the amount of packet flow of each user in accordance with the identifier for identifying the user at the reception of a packet from the channel interface, and compares the amount of packet flow with the flow threshold level defined in the user management table; selects a transfer path in accordance with a priority policy for switching a default path to another path having a different metric value, depending on the priority level, with reference to paths defined for the corresponding destination subnet address in the path management table, if the amount of packet flow exceeds the flow threshold level; and adds a source routing option for specifying addresses of routers to be passed, as indicated in the path management table, to the data received from the communication terminal, performs L2TP encapsulation for adding a header used in the L2TP tunnel, and switches a physical path by specifying destination routers.