Method of L2TP packet fast receive to improve the performance of L2TP network server in virtual private network router

摘要

PURPOSE: A method for receiving an L2TP(Layer 2 Tunneling Protocol) packet at high speed to improve LNS(L2TP Network Server) performance of a VPN(Virtual Private Network) router is provided to allow an LSL(Link Support Layer) block to analyze a header of the L2TP packet and interpret tunnel ID and call ID information, to transmit the information directly to a virtual serial device driver block for processing by a PPP(Point-to-Point Protocol) server, so as to reduce overheads. CONSTITUTION: If a packet is received to an LSL block(S101), whether the provision of an LNS function of a VPN router is available is decided(S102). If so, a pipe filter receives the packet and whether the packet is an IP(Internet Protocol) packet is checked(S103). If so, whether an IP payload is a UDP(User Datagram Protocol) packet is checked(S104). If so, whether the packet is an L2TP packet is checked(S105). If so, whether the packet is a data packet is checked(S106). If so, whether flow control is applied to the data packet is decided(S107). If above filtering conditions are all met, an L2TP header of the received packet is analyzed, to interpret a tunnel ID and a call ID(S108). An IP header, a UDP header and the L2TP header are eliminated(S109). The packet is delivered to an pipe API(Application Program Interface) of a virtual serial device driver to process the packet(S110,S111). And if any filtering condition is not met, an existing packet processing method is used to process the packet(S112).