Patent ID: 7339931

Claim:
A packet transfer apparatus connected to a plurality of broadcast segments and having a packet transfer control unit for transferring IP packets among the segments, wherein an internal subnetwork having a subnetwork address is formed by a set of segments among said plurality of broadcast segments, each of which accommodates a plurality of terminals, said packet transfer control unit comprises: a terminal management table for storing a plurality of entries each indicating a corresponding relation of a MAC address and an IP address of a terminal belonging to said internal subnetwork and an identifier of a segment to which the terminal is connected, means for transferring, when receiving from a source terminal connected to one of said set of segments in said internal subnetwork a MAC frame designating a destination terminal connected to one of said set of segments in said internal subnetwork by a destination IP address designating a destination terminal connected to another one of said set of segments in said internal subnetwork, an IP packet extracted from the received frame to the segment to which said destination terminal is connected by referring to said terminal management table, and said packet transfer control unit comprises: a routing table in which a plurality of entries each indicating routing control information corresponding to the address of one of said subnetworks are registered, an entry corresponding to the address of said internal subnetwork registered in the routing table including a segment identifier indicating that the internal subnetwork is comprised of a plurality of segments, and means for specifying by referring to said routing table and said terminal management table, when an IP packet destined to a terminal belonging to said internal subnetwork is received from a segment connected to an external subnetwork, a segment to which a destination terminal is connected, thereby to transfer the received packet to the segment.