This paper describes a new IP forwarding table searching scheme based on Longest Prefix Matching that can be implemented on a general logic controller together with high-speed DDR II (Double Date Rate II)SDRAM (Synchronous Dynamic Random Access Memory).

The paper design a method which was used for passive preventing DDoS attack based on users associated with IP-list technique.

Through the analysis of the types of IP access list and ARP protocol,and how to deploy 1705 router,the author realized two-way binding of local area network IP and MAC address.

Introduction of new internet protocol IPV6;