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The routing tables of Distributed Hash Tables (DHTs) can vary from size O(1) to O(n). Currently, what is lacking is an analytic framework to suggest the optimal routing table size for a given workload. This paper (1) compares DHTs with O(1) to O(n) routing tables and identifies some good design points; and (2) proposes protocols to realize the potential of those good design points.We use total traffic as the uniform metric to compare heterogeneous DHTs and emphasize the balance between maintenance cost and lookup cost. Assuming a node on average processes 1,000 or more lookups during its entire lifetime, our analysis shows that large routing tables actually lead to both low traffic and low lookup hops. These good design points translate into one-hop routing for systems of medium size and two-hop routing for large systems.Existing one-hop or two-hop protocols are based on a hierarchy. We instead demonstrate that it is possible to achieve completely decentralized one-hop or two-hop routing, i.e., without giving up being peer-to-peer. We propose 1h-Calot for one-hop routing and 2h-Calot for two-hop routing. Assuming a moderate lookup rate, compared with DHTs that use O(log n) routing tables, 1h-Calot and 2h-Calot save traffic by up to 70% while resolving lookups in one or two hops as opposed to O(log n) hops.

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In an ITS system, seemingly unrelated tickets created by end users and monitoring systems can coexist and have the same root cause. The connection between failed resource and malfunctioning services is not realized automatically, but often established manually by means of human intervention. This need for human involvement reduces productivity. The introduction of automation would increase productivity and therefore reduce the cost of incident resolutionIn this paper, we propose a model to correlate incident tickets based on three criteria. First, we employ a category-based correlation that relies on matching service identifiers with associated resource identifiers, using similarity rules. Secondly, we correlate the configuration items which are critical to the failed service with the earlier identified resource tickets in order to optimize the topological comparison. Finally, we augment scheduled resource data collection with constraint adaptive probing to minimize the correlation interval for temporally correlated tickets. We present experimental data in support of our proposed correlation model.