Finding and Mitigating Geographic Vulnerabilities in Mission Critical Multi-Layer Networks
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In Air Trafﬁc Control (ATC), communications outages may lead to immediate loss of communications or radar contact with aircraft. In the short term, there may be safety related issues as important services including power systems, ATC, or communications for ﬁrst responders during a disaster may be out of service. Signiﬁcant ﬁnancial damage from airline delays and cancellations may occur in the long term. This highlights the different types of impact that may occur after a disaster or other geographic event. The question is How do we evaluate and improve the ability of a mission-critical network to perform its mission during geographically correlated failures? To answer this question, we consider several large and small networks, including a multi-layer ATC Service Oriented Architecture (SOA) network known as SWIM. This research presents a number of tools to analyze and mitigate both long and short term geographic vulnerabilities in mission critical networks. To provide context for the tools, a disaster planning approach is presented that focuses on Resiliency Evaluation, Provisioning Demands, Topology Design, and Mitigation of Vulnerabilities. In the Resilience Evaluation, we propose a novel metric known as the Network Impact Resilience (NIR) metric and a reduced state based algorithm to compute the NIR known as the Self-Pruning Network State Generation (SP-NSG) algorithm. These tools not only evaluate the resiliency of a network with a variety of possible network tests, but they also identify geographic vulnerabilities. Related to the Demand Provisioning and Mitigation of Vulnerabilities, we present methods that focus on provisioning in preparation for rerouting of demands immediately following an event based on Service Level Agreements (SLA) and fast rerouting of demands around geographic vulnerabilities using Multi-Topology Routing (MTR). The Topology Design area focuses on adding nodes to improve topologies to be more resistant to geographic vulnerabilities. Additionally, a set of network performance tools are proposed for use with mission critical networks that can model at least up to 2nd order network delay statistics. The ﬁrst is an extension of the Queueing Network Analyzer (QNA) to model multi-layer networks (and speciﬁcally SOA networks). The second is a network decomposition tool based on Linear Algebraic Queueing Theory (LAQT). This is one of the ﬁrst extensive uses of LAQT for network modeling. Beneﬁts, results, and limitations of both methods are described.
Table of Contents
Introduction -- SWIM Network - Air traffic Control example -- Performance analysis of mission critical multi-layer networks -- Evaluation of geographically correlated failures in multi-layer networks -- Provisioning and restoral of mission critical services for disaster resilience -- Topology improvements to avoid high impact geographic events -- Routing of mission critical services during disasters -- Conclusions and future research -- Appendix A. Pub/Sub simulation model description -- Appendix B. ME Random Number Generation