Fault-Tolerant Broadcasts in CAN
J. Rufino, P. Verissimo, G. Arroz, C. Almeida and
Selected sections of this report were published in the Digest of
Papers, The 28th IEEE International Symposium on Fault-Tolerant
Computing, Munich, Germany, June, 1998.
Fault-tolerant distributed systems based on field-buses may take
advantage from reliable and atomic broadcast. There is a current
belief that CAN native mechanisms provide atomic broadcast. In this
paper, we dismiss this misconception, explaining how network errors
may lead to: inconsistent message delivery; generation of message
duplicates. These errors may occur when faults hit the last two bits
of the end of frame delimiter. Although rare, its influence cannot be
ignored, for highly fault-tolerant systems. Finally,
we give a protocol suite that handles the problem effectively.
Also available extended report (gzip postscript), (pdf).