Fujitsu Corporation

Raghu Sastry

Richard L Schober, Jr

Thomas M Wicki

Jeffrey D Larson

Albert Mu

Hirotaka Tamura

Yoichi Koyanagi

John R Slice

Patrick James Helland

Kohtaro Gotoh

A method and system performs automatic deskew tuning and alignment across high-speed, parallel interconnections in a high performance digital system to compensate for inter-bit skew. Rather than using a VDL, digital elements such as registers and multiplexers are used for performing the automatic deskew tuning and alignment procedure. The result is a simpler, more robust deskew system capable of operating over a wider range of input values with greater accuracy and over a broader range of temperatures. In addition, the method and apparatus performs a one to four unfolding of the signal on each interconnection. The system includes a deskew controller and a plurality of deskew subsystems. The deskew controller automatically computes the amount of delay needed to correct the skew on each interconnection and feeds a different (or appropriate) delay value to each deskew subsystem located at the receiving end of each interconnection.

System and method for automatic deskew across a high speed, parallel interconnection

A method and system performs automatic deskew tuning and alignment across high-speed, parallel interconnections in a high performance digital system to compensate for inter-bit skew. Rather than using a VDL, digital elements such as registers and multiplexers are used for performing the automatic deskew tuning and alignment procedure. The result is a simpler, more robust deskew system capable of operating over a wider range of input values with greater accuracy and over a broader range of temperatures. In addition, the method and apparatus performs a one to four unfolding of the signal on each interconnection. The system includes a deskew controller and a plurality deskew subsystems. The deskew controller computes the amount of delay needed to correct the skew on each interconnection and feeds a different (or appropriate) delay value to each deskew subsystem located at the receiving end of each interconnection.

A method and apparatus automatically initialize and tune a link in a network system. The link couples one router to another router and may be implemented as a high speed, plesiochronous, parallel link. The apparatus includes a first link control unit coupled to a first end of the link and a second link control unit coupled to a second end of the link. The second link control unit is capable of communicating with the first link control unit to achieve automatic adjustment of the operating parameters of the link to maximize signal propagation across and minimize the power consumption of the link. The method of initializing and tuning across a high speed link in a network is also disclosed.

Automatic initialization and tuning across a high speed, plesiochronous, parallel link

A system and method for controlling data transmission between two network elements. A first port of a transmitting element is coupled to a second port of a receiving element. The second port includes buffers for temporarily storing received data until the data can be sent to another element. Included in the transmitting element are a received-currently-full register (RCFR), a sent-and-not-received register (SANRR), and a buffer-busy register (BBR). The transmitting element checks its BBR to determine if a buffer in the receiving element is available. The availability of buffers can be determined using a single priority protocol or a multiple priority protocol. If a buffer is available, the transmitting element transmits a data frame to the receiving element and sets the SANRR and the BBR to indicate that a frame has been sent (and that no acknowledgment has been received), that the selected buffer in the receiver is full, and that no additional data frames are to be sent to this buffer until the buffer is empty. When data is received by the receiving element, it is sent to an available buffer. When the data is received by the buffer, the receiving element sets a bit in a currently-full register (CFR) and a bit in a next-message-to-send register (NMTSR). A control signal is transmitted by the data receiving element on the same signal line as data that is being sent from the data receiving element to the data transmitting element. The data receiving element can multiplex the frames being sent in this direction with the control signal. When the transmitting element receives the control signal, it resets a bit associated with a buffer in the SANRR if the bit is set in the SANRR and if the associated bit in the NMTSR portion of the control signal is set.

System and method for controlling data transmission between network

A method and apparatus for detecting and isolating an interconnect fault in a packet switched network generates a parity check error code for status messages which are used for flow control in a packet switched network. The packet switched network uses a reverse flow control method wherein status messages are sent locally between adjacent nodes. A receiving node uses status messages to inform an adjacent node of the availability of the input buffers located in the receiving node. Included in the status message is a parity check code that is sent sequentially with the status message using two phases of a clock. The parity check code is a one bit parity check for each bit of the status message. Faults on the local interconnect are detected at the receiving node by performing a one bit parity check on the received status message using the accompanying parity code. Because the status message and the parity check code are transmitted over the same physical bit connections, the one bit parity checks detects any 'stuck at' or 'open' faults in the link.

Interconnect fault detection and localization method and apparatus

An plesioasynchronous and asynchronous router circuit communicates with neighboring router circuits and nodes. Each of the router circuits includes a plurality of input ports for receiving frames of data and a plurality of output ports for transmitting frames of data. Each router circuit further includes a plurality of input buffers for storing frames of data received at an input port, and an arbiter system for choosing one of several input buffers associated with a particular one of said output ports. The arbiter system includes a plurality of arbiter subsystems associated with corresponding ones of said plurality of output ports. The plesioasynchronous and asynchronous router circuit further includes a crossbar switch for connecting an arbiter selected input buffer with a particular one of said output ports.

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Santa Clara, CA, United States of America

Raghu Sastry