Topic
Equal-cost multi-path routing
About: Equal-cost multi-path routing is a research topic. Over the lifetime, 10472 publications have been published within this topic receiving 249362 citations.
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TL;DR: This paper deals with a generalization of the Vehicle Routing Problem with Time Windows that considers time-dependent travel times and costs and converts it into an Asymmetric Capacitated Vehicle Routed Problem that can be solved both optimally and heuristically with known codes.
59 citations
TL;DR: The proposed modified quantum-behaved particle swarm optimization (QPSO) method for QoS multicast routing is converted into an integer programming problem with QoS constraints and is solved by the QPSO algorithm combined with loop deletion operation.
59 citations
TL;DR: Some new refinements to improve the capabilities of column generation approaches in this context are proposed, with a focus on the subproblem phase, and the notion of Limited Discrepancy Search is introduced.
Abstract: Column generation is a well-known mathematical programming technique based on two components: a master problem, which selects optimal columns (variables) in a restricted pool of columns, and a subproblem that feeds this pool with potentially good columns until an optimality criterion is met. Embedded in Branch and Price algorithms, this solution approach proved to be very efficient in the context of numerous vehicle routing problems, where columns represent feasible vehicle routes. The subproblem is then usually expressed as a shortest path problem with resource constraints, which can be solved using dynamic programming methods that are generally very effective in practice. In this paper, we propose some new refinements to improve the capabilities of column generation approaches in this context, with a focus on the subproblem phase. For the sake of simplicity, we restrict our study to the case of the Vehicle Routing Problem with Time Windows. We first introduce the notion of Limited Discrepancy S...
59 citations
TL;DR: Evaluation results for several different topologies show that computing the up*/down* routing tables by using the new methodology increases throughput by a factor of up to 2.48 in large networks with respect to the traditional methodology, and also reduces latency significantly.
Abstract: Networks of workstations (NOWs) are being considered as a cost-effective alternative to parallel computers. Most NOWs are arranged as a switch-based network and provide mechanisms for discovering the network topology. Hence, they provide support for both regular and irregular topologies, which makes routing and deadlock avoidance quite complicated. Current proposals use the up*/down* routing algorithm to remove cyclic dependencies between channels and avoid deadlock. However, routing is considerably restricted and most messages must follow nonminimal paths, increasing latency and wasting resources. We propose and evaluate a simple and effective methodology to compute up*/down* routing tables. The new methodology is based on computing a depth-first search (DPS) spanning tree on the network graph that decreases the number of routing restrictions with respect to the breadth-first search (BFS) spanning tree used by the traditional methodology. Additionally, we propose different heuristic rules for computing the spanning trees to improve the efficiency of up*/down* routing. Evaluation results for several different topologies show that computing the up*/down* routing tables by using the new methodology increases throughput by a factor of up to 2.48 in large networks with respect to the traditional methodology, and also reduces latency significantly.
59 citations
TL;DR: This paper introduces sociable routing, a novel routing strategy that selects a subset of optimal forwarders among all the nodes and relies on them for an efficient delivery.
Abstract: The problem of choosing the best forwarders in Delay-Tolerant Networks (DTNs) is crucial for minimizing the delay in packet delivery and for keeping the amount of generated traffic under control. In this paper, we introduce sociable routing, a novel routing strategy that selects a subset of optimal forwarders among all the nodes and relies on them for an efficient delivery. The key idea is that of assigning to each network node a time-varying scalar parameter which captures its social behavior in terms of frequency and types of encounters. This sociability concept is widely discussed and mathematically formalized. Simulation results of a DTN of vehicles in urban environment, driven by real mobility traces, and employing sociable routing, is presented. Encouraging results show that sociable routing, compared to other known protocols, achieves a good compromise in terms of delay performance and amount of generated traffic.
59 citations