Walking Through Waypoints

Amiri, Saeed Akhoondian; Foerster, Klaus-Tycho; Schmid, Stefan

doi:10.1007/978-3-319-77404-6_4

Cited by 5 publications

References 56 publications

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Walking Through Waypoints

2020

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We initiate the study of a fundamental combinatorial problem: Given a capacitated graph $$G=(V,E)$$G=(V,E), find a shortest walk (“route”) from a source $${s\in V}$$s∈V to a destination $$t\in V$$t∈V that includes all vertices specified by a set $$WP \subseteq V$$WP⊆V: the waypoints. This Waypoint Routing Problem finds immediate applications in the context of modern networked systems. Our main contribution is an exact polynomial-time algorithm for graphs of bounded treewidth. We also show that if the number of waypoints is logarithmically bounded, exact polynomial-time algorithms exist even for general graphs. Our two algorithms provide an almost complete characterization of what can be solved exactly in polynomial time: we show that more general problems (e.g., on grid graphs of maximum degree 3, with slightly more waypoints) are computationally intractable.

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Walking Through Waypoints

2020

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CASA: Congestion and Stretch Aware Static Fast Rerouting

Foerster

Pignolet²,

Schmid

et al. 2019

IEEE INFOCOM 2019 - IEEE Conference on Computer Communications

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To meet the stringent requirements on the maximally tolerable disruptions of traffic under link failures, many communication networks feature some sort of static failover mechanism for fast rerouting. However, configuring such static failover mechanisms to achieve a high degree of robustness is known to be challenging, in particular when packet tagging or dynamic node state cannot be used. This paper initiates the systematic study of such local fast failover mechanisms which not only provide connectivity guarantees, even under multiple link failures, but also account for the quality of the resulting failover routes, with respect to locality (i.e., route length) and congestion. Failover quality has received less attention in the literature so far, yet it is increasingly important to support emerging applications. We first show that there exists an inherent tradeoff in terms of achievable locality and congestion of failover routes. We then present CASA, an algorithm providing a high degree of robustness as well as a provable quality of fast rerouting. CASA combines two crucial static resilient routing techniques: combinatorial designs and arc-disjoint arborescences. We complement our formal analysis with a simulation study, in which we compare our algorithms with the state-of-the-art in different scenarios and show benefits in terms of stretch, load, and resilience.

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