Quasi-pushout method associated with upper-layer packet discarding control for packet communication systems with shared buffer memory

A quasi-pushout method for selective pushout in a shared-buffer packet communication system, comprising the steps of:

• when a first packet is entering said system for queuing and said shared buffer has been used up, pushing out a second packet from a quasi-longest queue pointed by an quasi-longest queue pointer to release a space;
• entering said first packet to its destination queue by taking the released space;
• updating the length of said destination queue;
• comparing the length of said destination queue and that of said quasi-longest queue, and if the former is longer, updating said quasi-longest queue pointer to point to said destination queue;
• when a third packet departs from an output queue, updating the length of said output queue;
• and
• comparing the length of said output queue and that of said quasi-longest queue, and if the former is longer, updating said quasi-longest queue pointer to point to said output queue.

A packet communication system with shared buffer memory and selective pushout packet discarding control, comprising:

• a packet communication module comprising:
• at least one input port for receiving packets;
• at least one output port for transmitting packets;
• a shared buffer memory having at least one queue for organizing buffered packets;
• and
• a processor for processing the arrival and departure of packets, comprising a quasi-longest queue pointer pointing to one of said queues as a quasi-longest queue on which said selective pushout discarding is performed, wherein said quasi-longest queue pointer is updated by said processor on every queue length changing events.

An input-only quasi-pushout method associated with upper-layer packet discarding control, for selective pushout in a shared-buffer packet communication system, comprising the steps of:

• when a first packet is entering said system for queuing and said shared buffer has been used up, pushing out a second packet from a queue containing a damage upper-layer packet, and if there is no damaged upper-layer packet, pushing out said second packet from a quasi-longest queue pointed by an quasi-longest queue pointer, to release a space;
• entering said first packet to its destination queue by taking the released space;
• updating the length of said destination queue;
• and
• comparing the length of said destination queue and that of said quasi-longest queue, and if the former is longer, updating said quasi-longest queue pointer to point to said destination queue.

A quasi-pushout method associated with upper-layer packet discarding control, for selective pushout in a shared-buffer packet communication system comprising the steps of:

• when a first packet is entering said system for queuing and said shared buffer has been used up, pushing out a second packet from a queue containing a damaged upper-layer packet, and if there is no damaged upper-layer packet, pushing out said second packet from a quasi-longest queue pointed by an quasi-longest queue pointer, to release a space;
• entering said first packet to its destination queue by taking the released space;
• updating the length of said destination queue;
• comparing the length of said destination queue and that of said quasi-longest queue, and if the former is longer, updating said quasi-longest queue pointer to point to said destination queue;
• when a third packet departs from an output queue, updating the length of said output queue;
• and
• comparing the length of said output queue and that of said quasi-longest queue, and if the former is longer, updating said quasi-longest queue pointer to point to said output queue.

A packet communication system with shared buffer memory and selective pushout packet discarding control, comprising:

• a packet communication module comprising:
• at least one input port for receiving packets;
• at least one output port for transmitting packets;
• a shared buffer memory having at least one queue for organizing buffered packets;
• and
• a processor for processing the arrival and departure of packets, comprising:
• a damage flag and a damaged-queue pointer indicating the presence of a damaged upper-layer packet and the queue storing said damaged upper-layer packet respectively;
• and
• a quasi-longest queue pointer pointing to one of said queues as a quasi-longest queue on which said selective pushout discarding is performed if no damaged upper-layer packet exists, wherein said quasi-longest queue pointer is updated by said processor on every queue length changing events.