Towards an optimal network survivability threshold

Without empirical insights into the survivability and resiliency of networks, operators and maintainers can only speculate about the efficacy of key network infrastructures. Outage reporting is a key aspect of integrated network management, and requires special consideration by network operators. For instance, the outage is to be deemed a threat to network survivability and resiliency. This paper considers the appropriateness of a network survivability reporting threshold by investigating the optimality of different thresholds, and threshold types. We wish to search for an optimal threshold, which minimizes the number of reports, and maximizes the amount of communication loss exposed by the reports. As a consequence, we define here a threshold figure of merit, which is the ratio of the communications loss and the number of outages exposed relative to a baseline reporting threshold, and seek to maximize this metric. Over 19 000 actual network outages are used to investigate optimal reporting thresholds. Results indicate that network operator perceptions of network survivability and resiliency depend not only on the magnitude of the threshold, but also on the threshold type.