Sun Microsystems, Inc.

Thomas J Moser

Randall David Rettberg

David L Satterfield

Daniel R Cassiday

A system and method for superimposing a sequence number of a packet into the CRC segment of the packet thereby allowing more bandwidth in the payload portion of the packet for carrying data is described. Also described is a method of acquiring additional information on the type of error in a packet, e.g., data transmission errors or sequence errors, from analyzing a CRC error. For example, a reported CRC error can be the result of the receipt of a packet with a sequence number the receiver is not expecting (which is a normal occurrence on transmission links due to transmitters resending packets that a receiver has already accepted) or can result from a real error in the transmission of a packet. A first error code check (CRC) value is calculated for the payload segment of a data packet. A second CRC value is calculated for the sequence number of the data packet. The first CRC value and the second CRC value are combined thereby creating a third CRC value. The third CRC value is then combined with the payload segment of the data packet thereby creating a data packet that can be transmitted across the link.

Method for superimposing a sequence number in an error detection code in a data network

System and method for rapidly calculating CRC values for messages including encoded bits is described. Tabularized CRC values are used in combination with a logical grid to quickly determine an appropriate CRC value of a message. This determination can take into account encoded inversion bits in the message. A collection of pre-calculated CRC values are arranged in a single-column table and then implemented with selected bits of a message by superimposing the bits in each CRC value onto a logical grid. Vertical lines of the grid are associated with 30 exclusive OR (XOR) gates and horizontal lines are associated with bits in an 88-bit message (or the 30 bits of a CRC value or with 8 bits of a sequence number). Through this grid, the inputs to the XOR gates are determined, thereby facilitating rapid calculations of CRC values due to the high processing speeds possible in XOR gates.

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Acton, MA, United States of America

Thomas J Moser