Method and system for providing differentiated service on a per virtual circuit basis within a packet-based switch/router

A method for managing traffic in a packet-based switch/router that has an input interface for receiving traffic on multiple virtual circuits (VCs) and an output interface for transmitting traffic on multiple VCs, said method comprising:

• receiving fixed-length cells;
• re-assembling variable-length packets from said fixed-length cells;
• classifying said variable-length packets into traffic classes;
• associating said variable-length packets with a VC;
• on a per-VC basis, enqueuing said variable-length packets directly into a VC-specific segmentation and re-assembly (SAR) queue if there is queue space available in said VC-specific SAR queue;
• and
• on a per-VC basis, enqueuing said variable-length packets into class-specific queues if there is not queue space available in the respective VC-specific SAR queue.

A packet-based switch/router comprising:

• an input interface for receiving traffic on multiple virtual circuits (VCs);
• an output interface for transmitting traffic on multiple VCs;
• a packet classifier for classifying packets into traffic classes based on packet header information;
• a demultiplexer for associating packets with a VC;
• VC-specific and class-specific queues;
• VC-specific segmentation and re-assembly (SAR) queues;
• an enqueue module for enqueuing packets by traffic class into said VC-specific and class-specific queues;
• a dequeue module for dequeuing packets from said VC-specific and class-specific queues to said VC-specific SAR queues a quality of service (QoS)/SAR module for dequeuing packets from said VC-specific SAR queues.

A packet-based switch/router comprising:

• an input interface for receiving traffic on multiple virtual circuits (VCs);
• an output interface for transmitting traffic on multiple VCs;
• a packet classifier for classifying received packets into traffic classes based on packet header information;
• a demultiplexer for associating packets with a VC;
• means for enqueuing packets into VC-specific and class-specific queues;
• means for dequeuing packets from said VC-specific and class-specific queues into VC-specific segmentation and re-assembly (SAR) queues means for dequeuing packets from said VC-specific SAR queues for segmentation into fixed-length cells.

A packet-based switch/router comprising:

• an input interface for receiving traffic on multiple virtual circuits (VCs);
• an output interface for transmitting traffic on multiple VCs;
• a packet classifier for classifying packets into traffic classes based on packet header information;
• a demultiplexer for associating packets with a VC;
• means for enqueuing said packets directly into VC-specific segmentation and re-assembly (SAR) queues if there is queue space available in said VC-specific SAR queues and if there are no packets in class-specific queues of the respective VCs or into said class-specific queues of the respective VCs if there is no queue space available in said VC-specific SAR queues means for dequeuing packet from said VC-specific SAR queues for segmentation into fixed-length cells.