Industrial Technology Research Institute

Tai-Chung Chang

Yao-Tzung Wang

Huan-Pin Tseng

Kuo-Yen Fan

Paul Huang

A shared memory management mechanism and method for a high-speed network releases network packets efficiently and maintains the requirement of First In First Out. A series of linked lists including a linked list for each output queue and a linked list of used broadcast packets aids a buffer manager in efficiently managing the buffers in the shared memory. The linked lists include a special data format that encodes the broadcast status, links, and whether the next entry in the list is for unicast or broadcast frames. A scanning procedure scans the broadcast status to efficiently release the broadcast frame buffers. A dynamic scanning procedure consumes less bandwidth than the scanning procedure to efficiently release the broadcast frame buffers.

Shared buffer management mechanism and method using multiple linked lists in a high speed packet switching system

A scheme for arbitrating access to a data bus shared among a plurality of competing sources is provided. Each competing source is assigned an adjustable priority weighting value (PWV) which is initially set to an initial value based on the bandwidth requirements of the competing source. During arbitration, the PWVs of those competing sources requesting access to the bus are compared, and the competing source with the smallest PWV is granted access. The PWV of the competing source which was granted access to the bus is reset to its initial value and the PWV of each competing source which requested, but was denied, access is reduced by one for subsequent comparisons. The arbitration scheme of the present invention is further applied to two-level arbitration. Each competing source is classified into a competing source group, and the requests from the grouped competing sources are processed by first level arbitration. First level arbitration passes one competing source for each group to a second level arbiter. The second level arbiter compares the PWVs of the competing sources resulting from first level arbitration to determine the competing source with the smallest PWV, and adjusts the PWVs after access to the bus has been granted.

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Hsin-Chu, Taiwan

Tai-Chung Chang