Method for routing a packet of a router device

PURPOSE: A packet routing method of a router apparatus is provided to offer a series of routing information assortatively, thereby minimizing the whole packet processing time of the packets and maximizing the whole routing capability of the router apparatus. CONSTITUTION: In the routing apparatus(20), a main processing(11) includes a main cache table(11a). In the table(11a), among several items included to an entry of a routing table(14), especially, the kernel of items is copied and stored to the main cache table(11a) separately. "Cache IP(Internet Protocol) address" included to the entry of the main cache table(11a) is the same value as "destination IP address" included to the entry of an IP routing table(14a). "The latest IP address" of the latest "packet transmission procedure" and "the latest interface" corresponding to the latest IP address are separately stored to the latest cache table(11b). The main processing(1) can perform a series of packet transmission procedures smoothly by using practically the main cache table(11a) and the latest cache table(11b) without transmitting the packet received to oneself to a protocol region(12), for example, an IP region(12a).