Network Reliability With Geographically Correlated Failures

Abstract

Abstract-Fiber-optic networks are vulnerable to natural disasters, such as tornadoes or earthquakes, as well as to physical failures, such as an anchor cutting underwater fiber cables. Such real-world events occur in specific geographical locations and disrupt specific parts of the network. Therefore, the geography of the network determines the effect of physical events on the network's connectivity and capacity.In this paper, we develop tools to analyze network failures after a 'random' geographic disaster. The random location of the disaster allows us to model situations where the physical failures are not targeted attacks. In particular, we consider disasters that take the form of a 'random' line in a plane. Using results from geometric probability, we are able to calculate some network performance metrics to such a disaster in polynomial time. In particular, we can evaluate average two-terminal reliability in polynomial time under 'random' line-cuts. This is in contrast to the case of independent link failures for which there exists no known polynomial time algorithm to calculate this reliability metric. We also present some numerical results to show the significance of geometry on the survivability of the network and discuss network design in the context of random line-cuts. Our novel approach provides a promising new direction for modeling and designing networks to lessen the effects of geographical disasters or attacks.

Robustness Comparison of 15 Real Telecommunication Networks: Structural and Centrality Measurements

“…The average two-terminal reliability (ATTR) delivers the probability of connectivity between a randomly chosen node pair [18]. ATTR is one when the network is fully connected; otherwise ATTR is the number of node pairs in every connected component divided by the total number of node pairs in the network.…”

“…When the network is fully connected, exactly one component exists and ATTR is one. Successive removal of nodes or links will bring it closer to zero [18]. If failures affect two topologies in the same percentage of nodes or links, the one that takes longer to reach a given critical ATTR can be considered the more robust [18].…”

“…Successive removal of nodes or links will bring it closer to zero [18]. If failures affect two topologies in the same percentage of nodes or links, the one that takes longer to reach a given critical ATTR can be considered the more robust [18]. ATTR provides an approximation to measure the network connections and to group networks with similar robustness.…”

Future research directions in design of reliable communication systems

“…Spatial correlation between failures in turn leads to the concept of a region failure, presented e.g., in [82,105,121], allowing for a simultaneous failure of several network elements located within a given area of a negative influence. Such a model seems to be appropriate for both node and link failures.…”

A new approach to design of weather disruption-tolerant wireless mesh networks

“…For instance, a group of wireless links located in the same area of a rain storm, may jointly encounter degradation of their effective capacity. As shown in [13,14], such region disruptions (i.e., events occurring in the area of a negative factor influence), are neither equally probable, nor statistically independent.…”