Patent ID: 8812754

Claim:
A network relay device for relaying a packet, comprising: a packet receiving section; a plurality of packet buffers operating independently of each other, in which the packet received by the packet receiving section is stored; a packet sending section configured to send the packet read from the packet buffer; a packet monitor section configured to measure a transfer amount of packets for a certain period of time; and a packet buffer control section configured to control the packet buffer in accordance with the transfer amount of the packets; wherein the packet buffer control section determines an effective buffer number required for the device depending on the transfer amount of the packets measured by the packet monitor section and a predetermined threshold, and controls the supply of power or clock to the packet buffers to be turned ON or OFF in accordance with the determined effective buffer number; wherein a write control into the packet buffer manages a write pointer pointing to write position information in the packet buffer control section, in which every time one packet is received, the value of the write pointer is increased, and the packet is written into the packet buffer in accordance with the write pointer, wherein a read control from the packet buffer manages a read pointer pointing to read position information in the packet buffer control section, in which the packet is read from the packet buffer, and the value of the read pointer is increased every time the packet is read in response to an occurrence of an event that there is a difference of one or more between the value of the write pointer and the value of the read pointer, and wherein in response to an occurrence of an event that the packet buffer control section determines that the effective buffer number is decreased and there is no packet arriving at the packet receiving section within a predetermined period of time, a dummy packet set to be discarded within the self network relay device is inputted into the packet receiving section and flowed through the self network relay device to move the write pointer and the read pointer on the packet buffer scheduled to halt onto an effective buffer.