Patent ID: 8082474

Claim:
A communication interface device comprising: shadow selection logic to select a driver bit position as a shadowed driver value; line drivers to transmit data for the selected driver bit position and the shadowed driver value on separate link segments of a bus; shadow compare logic to compare a selected received value with a shadowed received value from the bus and identify a miscompare in response to a mismatch of the compare; and shadow counters to count a rate of the miscompare relative to a bus error rate over a period of time, wherein a defective link segment is identified in response to the rate of the miscompare within a predefined threshold of the bus error rate; wherein the bus cascade interconnects the communication interface device with a second communication interface device, and the bus further comprises downstream lanes and upstream lanes of differential-ended unidirectional link segments, the downstream lanes comprising: 13 downstream bit lanes, 2 spare downstream bit lanes, and a downstream clock, and the upstream lanes comprising: 20 upstream bit lanes, 2 spare upstream bit lanes and an upstream clock.