Patent ID: 7212529

Claim:
A system for retrieving a destination address of a packet, comprising: a packet storage unit for storing a packet which has plural-staged headers having respective destination addresses; an address information storage unit for storing a plurality of address information table, which stores address informations for each header; and an address retrieving unit functionally coupled to said packet storage unit and said address information storage unit, wherein said address retrieving unit generates at least one first-retrieval key from an external header information of said packet stored in said packet storage unit, said address retrieving unit also performs a first-retrieval to at least one of said plurality of address information table based on said at least one first-retrieval key and receives a first-returned value, which depends upon a first-retrieval result made, from said address information storage unit, said first-returned value indicating the presence or absence of any internal header in said packet, if said returned value indicates the presence of any internal header in said packet, then said address retrieving unit further generates at least one second-retrieval key from an internal header information of said packet, so that said address retrieving unit also performs a second-retrieval to at least other one of said plurality of address information table based on said at least one second-retrieval key and receives a second-returned value, which depends upon a second-retrieval result made, from said address information storage unit, said second-returned value indicates the presence or absence of any further internal header in said packet, and if said returned value indicates the absence of any internal header in said packet, then said address retrieving unit outputs a retrieval result.