Digital Equipment Corporation

Other

Moshe De-Leon

Simoni Ben-Michael

Michael Ben-Nun

Kadangode K Ramakrishnan

Peter J Roman

G Paul Koning

Henry S Yang

Shirish S Sathaye

A system for controlling the transmission of cells from a network node over multiple Virtual Circuits (VCs) is disclosed. The system performs traffic shaping, as required by connection based systems such as Asynchronous Transfer Mode (ATM), for each VC connected with a network node, so that the Quality of Service (Qos) parameters established when the connection was established are not exceeded. The system includes a process for scheduling the transmission of cells from the network node. The scheduling process periodically scans a table having entries corresponding to virtual circuits connected with the network node. During each scan of the table, the scheduler increments a sustainable rate accumulator field and a peak rate accumulator field of each table entry that corresponds with a virtual circuit that is open, and for which there is a cell ready to be transmitted. The scheduler further determines if the sustainable rate accumulator value is greater than or equal to a predetermined value and whether the peak rate accumulator value is greater than or equal to a predetermined value. If both conditions are true, then a cell may be transmitted on the virtual circuit corresponding with that table entry.

Traffic shaping system for asynchronous transfer mode networks

A system for controlling the transmission of cells from a network node over multiple virtual circuit is disclosed. The disclosed system performs traffic shaping for all virtual circuits connected with the network node. The system includes a virtual circuit table with one or more entries. Each virtual circuit table entry corresponds to a virtual circuit established with the network node. Each virtual circuit table further includes one or more Cell Rate Accumulator fields and a Time Stamp field. The system includes a schedule table having one or more entries. Each schedule table entry further includes one or more Cell Rate Accumulator fields and corresponding predetermined value fields. A schedule table loading process determines a virtual circuit on which a packet is to be transmitted, and then calculates a time elapsed since a last previous write of a virtual circuit table entry corresponding with that virtual circuit. The schedule table loading process then adds the time elapsed to the value of the Cell Rate Accumulator fields in that virtual circuit table entry, and stores the result of the addition into the corresponding Cell Rate Accumulator fields of the schedule table entry. The system further includes a process for periodically incrementing the Cell Rate Accumulator fields in the schedule table entry. A scanning process periodically increments the Cell Rate Accumulator fields. A transmitting process transmits a cell on the virtual circuit when the value of the Cell Rate Accumulator fields is greater than or equal to the corresponding predetermined values.

Traffic shaping system with virtual circuit table time stamps for

The invention improves the efficiency of buffer descriptor processing by performing descriptor prefetches, where multiple descriptors are read within the same descriptor bus transaction. The invention reads multiple buffer descriptors each time the bus is accessed. This allows for a smaller FIFO in a cut-through network adapter because it reduces the number of bus transactions needed to transfer data.

Buffer descriptor prefetch in network and I/O design

A system for controlling the transmission of cells from a network node over multiple Virtual Circuits (VCs) is disclosed. The system performs traffic shaping, as required by connection based systems such as Asynchronous Transfer Mode (ATM), for each VC connected with a network node, so that the Quality of Service (Qos) parameters established when the connection was established are not exceeded. The system includes a process for scheduling the transmission of cells from the network node. The scheduling process periodically scans a table having entries corresponding to virtual circuits connected with the network node. During each scan of the table, the scheduler increments a sustainable rate accumulator field, a peak rate accumulator field, and a latency accumulator field of each table entry that corresponds with a virtual circuit that is open, and for which there is a cell ready to be transmitted. The scheduler further determines if the sustainable rate accumulator value is greater than or equal to a predetermined value and whether the peak rate accumulator value is greater than or equal to a predetermined value. If both conditions are true, then a cell may be transmitted on the virtual circuit corresponding with that table entry. The system further provides that transmissions are scheduled on virtual circuits having the greatest latency since previous transmissions.

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Jerusalem, Israel

Moshe De-Leon