Packet transfer apparatus, scheduler, data transfer apparatus, and packet transfer method

A packet transfer apparatus for transferring communication packets, comprising:

• a plurality of buffer memories provided for each communication interface, where each of the plurality of buffer memories is partitioned into a plurality of buffer areas;
• a buffer control circuit which determines at least one attribute of at least one packet which is input into said packet transfer apparatus, stores the at least one packet in at least one of said plurality of buffer areas which is respectively associated with the at least one attribute in advance, in at least one of said plurality of buffer memories corresponding to at least one communication interface to which the at least one packet is to be output, and outputs a packet stored in one of said plurality of buffer areas in one of the plurality of buffer memories when the one of the plurality of buffer areas in the one of the plurality of buffer memories is selected;
• a plurality of first-stage schedulers corresponding to said plurality of buffer memories and each including a first register and a first selector, where information which indicates priorities of said plurality of buffer areas and can be varied during packet transfer processing is set in said first register, and said first selector refers to said information set in said first register at a packet transfer timing, selects one of said plurality of buffer areas which has a highest priority among at least one of the plurality of buffer areas storing at least one packet, and sends a selection result to said buffer control circuit;
• and
• a second-stage scheduler including a second register and a second selector, where information which indicates priorities of said plurality of buffer memories and can be dynamically varied is set in said second register, and said second selector refers to said information set in said second register when a packet can be transmitted, selects one of said plurality of buffer memories which has a highest priority among at least one of the plurality of buffer memories storing at least one packet, and sends a selection result to said buffer control circuit.

A data transfer apparatus for transferring data between a plurality of networks, comprising:

• a first communication port;
• a second communication port;
• a buffer memory partitioned into a plurality of buffer areas;
• a buffer control circuit which determines at least one attribute of at least one packet which is input through said first communication port, stores the at least one packet in at least one of said plurality of buffer areas which is respectively associated with the at least one attribute in advance, and outputs through said second communication port a packet stored in one of said plurality of buffer areas when the one of the plurality of buffer areas is selected;
• a plurality of registers in which information indicating priorities of said plurality of buffer areas is set, where the information can be changed during packet transfer processing;
• a selector which refers to said information set in said plurality of registers at a packet transmission timing, selects one of said plurality of buffer areas which has a highest priority among at least one of said plurality of buffer areas storing at least one packet, and sends a selection result to said buffer control circuit;
• and
• a processor which dynamically changes said information set in said plurality of registers.

A packet transfer method for transferring communication packets through a buffer memory partitioned into a plurality of buffer areas, comprising the steps of:

• (a) determining at least one attribute of at least one packet which is input, and storing the at least one packet in at least one of said plurality of buffer areas which is respectively associated with the at least one attribute in advance;
• (b) at a packet transmission timing, referring to information indicating priorities of said plurality of buffer areas, and selecting one of said plurality of buffer areas which has a highest priority among at least one of said plurality of buffer areas storing at least one packet;
• and
• (c) outputting a packet stored in the selected one of said plurality of buffer areas.