Method and apparatus for isolating faults in a network having serially

Abstract

A fault isolation system for use in a network in which bit errors resulting in detected code violation errors or disparity errors may be propagated from a first link to a second link of a network in which multiple serially coupled links may couple two devices. Errors in excess of a first threshold are detected at the receiving end of the first link, while errors in excess of a second threshold greater than the first threshold are detected at the receiving end of the second link. Errors are attributed to the first link in response to the detection of errors in excess of the thresholds on both links and are attributed to the link for which the threshold was exceeded in response to the detection of errors in excess of the threshold on only one of the links. If a substantial number of the bit errors resulting in the threshold being exceeded on the second link originated on the first link, the first threshold will also be exceeded with a high degree of probability. This prevents the erroneous identification of the second link as being the source of the fault where the fault actually originated from a condition on the first link.