Digital Equipment Corporation

Compaq Computer Corporation, Inc.

Other

Michael Ben-Nun

Kadangode K Ramakrishnan

Simoni Ben-Michael

Peter J Roman

Moshe De-Leon

G Paul Koning

Henry S Yang

Thomas J Schmidt

Siman-Tov Ben-Michael

Yifat Ben-Shahar

Niamh Darcy

Shirish S Sathaye

Winthrop J Wu

Larry Huppert

Simcha Perl

Bhupendra Shah

In accordance with principles of the invention, there is provided an arbitration system for multiple requesters of a shared data transfer resource, such as a system bus or a peripheral bus. The disclosed system arbitrates among multiple classes of requesters which are divided into multiple levels of a request hierarchy. In the example embodiment, the multiple requesters include logic for processing received data from the network, logic for processing data to be transmitted onto the network, logic for moving transmit and receive descriptors between the host memory and the adapter, logic for reporting status from the adapter to the host, and logic for generating an error and maintenance status update from the adapter to the host. The new system ensures fairness between transmit and receive processes, that FIFOs associated with transmit queues are not underrun, and further than notification of non-error and maintenance status changes are processed with minimal latency.

Arbitration system based on requester class and relative priority including transmit descriptor valid bit for a shared resource having multiple requesters

A method and related apparatus enables one station on a local area network (LAN) 24 to securely wake up another station on the LAN 24 although the stations may be physically remote from each other. A workstation 12, acting as a remote management console, generates a secure wake-up packet 42 intended for a desktop computer 14 on the LAN 24. The desktop computer 14 is operating in a sleep state. The data section of the secure wake-up packet has a particular sequence of data including a synchronization sequence 46, a MAC address sequence 48 and a password sequence 50. The desktop computer 14 has a network interface 64 for detecting and processing secure wake-up packets 70 when that network interface 64 is operating in a remote access control mode. The network interface 64 verifies that MAC address sequence 48 corresponds to the MAC address of the desktop computer 14 and that the password sequence 50 has a predetermined relationship with a password required to wake up the desktop computer 14. The network interface 64 issues a wake-up signal to wake up the desktop computer 14 when a valid secure wake-up packet is processed.

Method and apparatus for secure remote wake-up of a computer over a

A relatively small FIFO queue is located on a semiconductor chip receiving and transmitting data in a computer system, typically a computer network. The FIFO queue has additional storage capability in the form of an expansion into the local memory of the computer system. The front and back ends of the FIFO, which are involved in receiving and transmitting data, are implemented on the chip. The FIFO expands into the space provided in the local memory only when the on-chip portion of the FIFO is full. The middle portion of the FIFO resides in expansion in the local memory. The local memory is accessed only in bursts of multiple credits, both for read transactions and for write transactions.

Method and apparatus to expand an on chip FIFO into local memory

In accordance with principles of the invention, there is provided an arbitration system for multiple requesters of a shared data transfer resource, such as a system bus or a peripheral bus. The disclosed system arbitrates among multiple classes of requesters which are divided into multiple levels of a request hierarchy. In the example embodiment, the multiple requesters include logic for processing received data from the network, logic for processing data to be transmitted onto the network, logic for moving transmit and receive descriptors between the host memory and the adapter, logic for reporting status from the adapter to the host, and logic for generating an error and maintenance status update from the adapter to the host. The new system ensures fairness between transmit and receive processes, that FIFOs associated with transmit queues are not underrun, and further that notification of non-error and maintenance status changes are processed with minimal latency.

Arbitration system based on requester class and relative priority

Arbitration system for a shared DMA logic on a network adapter with a

In an asynchronous transfer network (ATM), to prevent the bottleneck associated with a host central processing unit (CPU) trying to receive status information for a plurality of interrupts occurring over an interface input/output (I/O) bus, a method and apparatus which transfers all status information directly to the host memory without host involvement. The host CPU is then notified of this new status information via an interrupt. When status information is transferred to the host memory, consistency is ensured and the number of spurious interrupts are reduced. A host software driver may then read the latest status information from the interface I/O bus at its convenience any not incur any performance penalties of I/O accesses.

Method and apparatus for updating host memory in an adapter to minimize

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

An Asynchronous Transfer Mode (ATM) network device having a receiver portion capable of receiving ATM cells on one of a number of virtual circuits (VCs) from an upstream ATM switch, a local memory used to store the ATM cells, a management system to manage the local memory using a number of queues, a system for assembling ATM cells into packets, a system for transmitting the packets to a host memory, and a transmitter portion having a system for indicating the transmitting of packets to the host memory to the upstream ATM switch.

Local memory buffers management for an ATM adapter implementing credit

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

An Asynchronous Transfer Mode (ATM) network adapter having a receiver portion, the receiver portion capable of receiving a first plurality of ATM cells and assembling the first plurality of ATM cells into a first plurality of packets, and a transmitter portion, the transmitter receiving a second plurality of packets and segmenting the second plurality of packets into a second plurality of ATM cells, the receiving portion having a local memory for segmentation, while the transmitter portion having no local memory.

Method and apparatus for segmentation and reassembly of ATM packets

In an asynchronous transfer mode (ATM) endnode a method is provided by which ATM cells can experience a small delay from the ATM layer to the PHY layer to transmission on the ATM network. Such an arrangement includes providing the endnode with an ATM layer, the ATM layer having a first-in-first-out (FIFO) queue for transmitting transmit ATM traffic, providing the endnode with a PHY layer, the PHY layer having a FIFO queue for receiving the transmit ATM traffic, providing an interface between the FIFO queue of the ATM layer and the FIFO queue of the PHY layer for the flow of the transmit ATM traffic, providing a signal in the ATM endnode, providing a state machine in the ATM endnode, the state machine monitoring the signal in the ATM endnode, stalling the transfer of the transmit ATM traffic from the FIFO of the ATM layer to the FIFO of the PHY layer over the interface when the signal and the state machine indicate that the FIFO of the PHY layer is full, and transmitting the transmit ATM traffic from the FIFO of the ATM layer to the FIFO of the PHY over the interface. By causing the ATM layer to generate/transfer a continuous stream of cells to the PHY layer, the method can provide cell time indications to allow the ATM layer to synchronize itself to the network.

Method for controlled-latency transfer of transmitt ATM traffic and

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.

Traffic shaping system with transmit latency feedback for asynchronous

A host system and an ATM network adapter using a chaser packet are presented. The adapter receives cells over a virtual connection on the network and generates, in response to the host system, a chaser packet which allows the host to detect that all data has been transferred form the adapter buffers to host memory. When all data has been transferred, the host may release the virtual connection without data loss. The host and adapter may also transmit data. In data transmission, the chaser packet is used to determine that all data has been transmitted out onto the network before the sending host releases the virtual connection. The chaser packet is also used for resynchronization of credits where the ATM network uses credit-based flow control. The adapter uses the chaser packet to drain the local queue so that the link between the adapter and a source system may be resynchronized.

Method and apparatus to efficiently reuse virtual connections by means

An asynchronous transfer mode (ATM) network device having a receiver portion, the receiver portion capable of receiving ATM cells on virtual circuits (VCs) from an upstream ATM switch, a local memory used to store the ATM cells, managing local memory using queues, assembling ATM cells into packets, transmitting the packets to a host memory, resynchronizing ATM credits, and a transmitter portion, the transmitter portion indicating transmitting of packets to host memory to the upstream ATM switch.

Growing community of inventors

Jerusalem, Israel

Michael Ben-Nun