System and method for fair shared de-queue and drop arbitration in a buffer

Abstract

Systems and methods consistent with the present invention provide a mechanism that can efficiently manage multiple queues and maintain fairness among ports while not placing additional performance demands on the memory used to store the queue data structures. Within a port, high priority traffic is dropped only if it is consuming more than its fair share of bandwidth allocated to that port. Queue arbitration is of low performance cost and simple because it arbitrates only across queues per port, rather than across all the queues in parallel. Accordingly, fair arbitration with relatively little hardware cost.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application is related to U.S. patent application Ser. No. 12 / 473,408, entitled SYSTEM AND METHOD FOR SHARED BUFFER MANAGEMENT, filed on May 28, 2009, assigned to a common assignee, and the entirety of which is herein incorporated by reference.FIELD OF THE INVENTION[0002]The present invention generally relates to buffer management in a router, and relates more particularly to de-queue / drop arbitration for sharing buffer space.BACKGROUND OF THE INVENTION[0003]Network packet routers use buffer management techniques to share limited buffer space between various incoming data ports and classes of data packets. Typically, the packets are divided into cells that are managed by a set of queues. Packets from multiple ports are en-queued to multiple queues based on their classified priority and de-queued based on available bandwidth of the shared output port(s). Often the available output bandwidth is less than in aggregate input bandw...

AI Technical Summary

Benefits of technology

The present invention provides a method for packet drop arbitration in a data processing system, which involves determining an input port for which a packet should be dropped, selecting a queue for dropping the packet from a plurality of queues associated with the input port, and dropping the packet from the selected queue. The invention also provides a data processing system comprising a router with a memory, at least one output port, and a plurality of input ports, a plurality of queues stored in the memory, and a queue arbiter for de-queuing a packet from one of the plurality of queues to the output port, wherein the first level of arbitration is based on a selection of an input port and the second level of arbitration is based on priority of the at least two queues associated with the input port. The invention also includes a computer program product comprising computer-implemented instructions for performing a method of packet de-queue arbitration. The technical effects of the invention include improved efficiency in processing packets and reduced latency in data processing.

Problems solved by technology

Often the available output bandwidth is less than in aggregate input bandwidth and packets must be dropped because there is limited shared buffer memory.

However, there are many restrictions on implementing a buffer management scheme.

This situation may occur because there is low traffic on the other ports.

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