Network Appliance, Inc.

Netapp, Inc.

Alexander M Pass

Vitaly Revsin

Irina P Slutsky

A method and system for flow control in a reliable multicast communication protocol, in which a transmitting device transmits sets of multiple data transfer units (DTUs) referred to as 'bursts.' The transmitting device continues transmitting DTUs within a burst independently with regard to the receipt of any acknowledgements (referred to herein as 'status reports') from a number of receiving devices. The transmitting device continues to transmit multiple bursts until the transmitting device reaches a predetermined limitation, referred to as a &#x201c;burst sliding window&#x201d; size. The transmitting device transmit DTUs in bursts while a total number of outstanding bursts that have not been acknowledged as received correctly does not exceed the size of the burst sliding window. The burst sliding window size may reflect transmission capacity of the transmitting device and/or receipt capacity of the receiving devices.

Method and apparatus for flow control in a reliable multicast communication system

A system and method for reliably transmitting large amounts of data over a high speed network with large latency, such as a communication satellite based network. A transmitting device transmits data transfer units (DTUs) to one or more receiving devices. The transmitting device forms and transmits burst consisting of reliably delivered sets of multiple DTUs. Both the transmitting device and the receiving devices process multiple bursts in parallel, such that subsequent bursts can be transmitted and received prior to the correct receipt of a previously transmitted burst at all of the receiving devices, and/or prior to receipt of a status report at the transmitting device regarding a previously transmitted burst. The transmitting device operates to transmit subsequent bursts even before the receipt of a status information regarding a previous burst, and the receiving devices process subsequently received bursts while awaiting retransmission of a lost or damaged DTU from a previous burst.

Method and apparatus for optimizing channel bandwidth utilization by simultaneous reliable transmission of sets of multiple data transfer units (DTUs)

Reliable multicast communication is provided by sending data from a transmitting device to receiving devices as 'bursts' of data transfer units. Each receiving device provides status describing which data transfer units within each previously transmitted burst require retransmission. The transmitting device generates correction data based on this status information by determining a number of subsets of the data transfer units in the burst. Each data transfer unit subset must meet the following condition: if a data transfer unit is included in a given subset, for each receiving device in the group of receiving devices, that data transfer unit must be the only data transfer unit lost by that receiving device and included in that subset. The correction data for a given subset is obtained by applying an exclusive-OR (XOR) operation to all the data transfer units in the subset, and the output is sent to at least one of the receiving devices. Each correction data transfer unit includes the correction data itself, as well as a bit mask describing which data transfer units of the previously transmitted burst are within the subset associated with the correction data. Upon receiving a correction data transfer unit, a receiving device operates to restore a lost or damaged data transfer unit from the previously transmitted burst by applying an XOR operation to correction data in the correction data transfer unit and the correctly received data transfer units in the associated subset.

Method and apparatus for restoration of lost blocks in a multicast data transmission

A system and method for providing data delivery and processing status from at least one receiving device to a transmitting device. Data is sent to one or more receiving devices in bursts consisting of multiple data transfer units (DTUs). The receiving device or devices provide one or more status reports to the transmitting device, describing the delivery and processing status of bursts transmitted from the transmitting device. Each status report may represent the receive and/or processing status packet with regard to multiple bursts sent from the transmitting device to a receiving device. Status reports may be generated by a receiving device in response to detection of a predetermined condition such as the end of a received burst. Each status report may describe the receipt and/or processing status of all DTUs in all bursts that have previously been received by the receiving device from the transmitting device.

Method and apparatus for reliable delivery of status information for multiple sets of data units in a single packet

A system and a method for forward error correction (FEC) which are efficient in terms of computational requirements and the amount of redundant information that must be transmitted. Given a set of input data transfer units (DTUs), to be sent from a transmitting device to a receiving device, the disclosed system uses prime numbers to generate subsets of the input DTUs. Subsets generated in this way are used to generate corresponding error correction DTUs by applying an XOR operation to all DTUs of the subset. The error correction DTUs are then appended to the input DTUs and transmitted to the receiver(s) as part of a burst. The error correction DTUs accordingly provide error correction information for data DTUs transmitted within a burst, and are used by receiving devices to restore data DTUs within the burst that were damaged or lost.

Growing community of inventors

North Andover, MA, United States of America

Alexander M Pass