Fault-Tolerant Broadcasts in CAN

J. Rufino, P. Verissimo, G. Arroz, C. Almeida and L. Rodrigues

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).

Luís Rodrigues