Address search method and packet processing device

A packet processing device comprising:

• a first search table in which an entry including an index value and a destination address is registered;
• a second search table in which a combination of header information and a destination address is registered;
• a packet reception section that receives a packet to be transferred;
• a registration section that receives as an input a combination of header information and a destination address to be registered, calculates an index value by one-way function calculation using the input header information, registers the calculated index value and the input destination address in the first search table as a new entry when the calculated index value is different from the index value of an existing entry in the first search table, and registers a combination of the header information and the destination address represented by the existing entry together with a combination of the input header information and the destination address in the second search table and deletes the destination address of the existing entry when the calculated index value is the same as the index value of the existing entry;
• and
• a search section that searches, upon reception of the packet to be transferred, the first and the second search tables in parallel for the destination address of the packet by using the header information of the packet, wherein the destination address of the packet is searched from the first search table by using, as a key, an index value calculated by using the header information of the packet and is searched from the second search table by using the header information of the packet.