Alcatel Internetworking, (Pe), Inc.

Jeffrey J Walker

Greg W Davis

C Stuart Johnson

Method and apparatus for detecting signal transfer errors in a digital logic system that might occur in a transfer medium between a source device and a destination device. The method includes sending a first diagnostic signal of one or more bits from the source device through the transfer medium to the destination device; comparing the first diagnostic signal received by the destination device with a second diagnostic signal within the destination device to determine if a signal transfer error has occurred; inverting the first diagnostic signal; sending the inverted first diagnostic signal from the source device through the transfer medium to the destination device; and comparing the inverted first diagnostic signal received by the destination device with the second diagnostic signal to determine if a signal transfer error has occurred. Two embodiments of the invention are disclosed. To provide near real time detection without adding signal paths, the diagnostic signals are sent along established signal paths during a diagnostic clock cycle that is added to the normal clock cycles of the digital system.

Method for detecting signal transfer errors in near real time in a digital system

In a switching device such as a network switch having multiple ports and shared buffer memory, method and apparatus for regulating the amount of buffer memory requested by a port. The method includes determining a limit number of buffers that a port may use from the number of available buffers in memory and the number of buffers in memory currently in use by the port. The limit number and number of buffers currently is use are then compared, and the comparison is used to determine whether a buffer request by the port will be generated. In an illustrative embodiment, determining the limit number includes adding the number of available buffers in memory with the number of buffers in memory currently in use by the port to obtain a sum, and multiplying the sum by a port allocation factor. The port allocation factor may be set independently for each port. Apparatus within the switching device practices the method in accordance with the invention.

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Spokane, WA, United States of America

Jeffrey J Walker