One problem in the contemporary computer networks is monitoring the failure margin, i.e., what number of anomalies (intrusions, viruses, node and link failures, power losses, etc.) can be tolerated before the network performance degrades to unacceptable levels. It is important to develop techniques that can be used to predict the behavior of computer networks and to determine dynamically how much reserve capacity and failure margin are available when anomalies occur. A solution for this challenging problem can ensure the predictable behavior and productive performance of computer networks.

In this paper are studied some of the fault-tolerance properties of the "F-Cycle Ring" (FCR) family of network interconnects that are designed to maximize the network?s resistance to partitioning. In particular, the failure margin and the graceful performance degradation of one FCR topology for consecutive single failures are demonstrated.