An Improved Approach to Fault Tolerant Redundant Fiber Optic Ring Design for Polled Data Networks

This research investigates alternate methods of implementing a redundant communications ring for polled network applications. FDDI and a unique solution (the tone method) designed specifically for this application are compared. In polled networks one of the most critical parameters is the time required to interrogate all of the nodes in the network. This parameter, called the poll time, is compared for the two solutions under various operating conditions, including the instances when the ring is intact and when the ring has experienced a failure, causing it to operate in the redundant mode. As expected, the solution designed specifically for this application performed better than FDDI. The tone method, which requires very little overhead and is not limited by distance or number of nodes, is described in detail, as are the results of poll time comparisons.