Sprint Network Research Articles

Power‐aware routing in networks with quality of services constraints

AbstractCurrent network infrastructures are over‐provisioned and thus exhibit poor power efficiency at low traffic load. We consider networks consisting of bundled links, whereby each link has one or more physical cables that can be switched off independently. The problem at hand is to switch off redundant nodes and cables during off‐peak periods, while retaining the quality of services provided to existing traffic demands. Unfortunately, the problem to maximally shutdown redundant nodes and cables is Non‐deterministic Polynomial‐time (NP)‐complete. Henceforth, we design a fast heuristic, called Multiple Paths by Shortest Path First (MSPF), that aims to maximise the number of switched‐off nodes and cables subject to satisfying maximum link utilisation (MLU) and path length (PL) constraints. We have extensively evaluated the performance of MSPF on both real and synthetic topologies and traffic demands. Further, we have compared its performance against two state‐of‐the‐art techniques: GreenTE, usable when each link has one cable, and Fast Greedy Heuristic (FGH), which supports bundled links but only for networks without MLU and PL constraints. On the Sprint network, MSPF can save on average 5% more power as compared to GreenTE while incurring only 1% of GreenTE's running time. While yielding equivalent power savings, MSPF requires only 0.35% of FGH's running time. Finally, setting MLU to at most 50% and PL to no longer than the network diameter, MSPF reduces the power usage of the GÉANT topology by up to 91% for links consisting of 10 cables. For experiments on synthetic topologies with bundle size of 30, MSPF yields a power saving of 89.81%. Copyright © 2014 John Wiley & Sons, Ltd.

Network design methods for mitigation of intentional attacks in scale-free networks

Network robustness and network reliability are important issues in the design of Internet Service Providers' topologies. In this paper, we examine the structural characteristics of network topologies that affect robustness and reliability. We examine the interplay between the structural characteristics of network topologies and the resource capacity over-provisioning strategies when the network breakdowns subject to practical constraints (router technology) and economic considerations (link costs). We study the robustness of the Internet connectivity under node intentional harmful attack using two attacks strategies: static degree-based and static load-based. We find that the robustness of network topologies is affected by the variation of their structural characteristics. In our proposed approach, we show that highly-heterogeneous topologies have less robustness compared with lightly-heterogeneous topologies. The observations from the robustness study provide us useful insights for proposing multiple efficient preventive resource capacity over-provisioning strategies for mitigation of intentional attacks. The proposed strategies utilize the structural properties by calculating the excess traffic in case of single global cascading failure for each node and measure its influence on the other nodes as well as locally. The results show that our proposed strategies can significantly enhance the robustness and increase the resilience of network topology. We also show that highly-heterogeneous topologies have high resilience compared with lightly-heterogeneous topologies. By using real data from the Sprint network at the router level, we provide further empirical evidence in support of the proposed approach.

Beyond the Flickering Screen: Re-situating e-books

Beyond the Flickering Screen: Re-situating e-books

Feasibility of IP restoration in a tier 1 backbone

Large IP networks usually combine protection and restoration mechanisms at various layers of the protocol stack to minimize service disruption in the event of failures. Sprint has chosen an IP-based restoration approach for building a highly available tier 1 IP backbone. This article describes the design principles of Sprint's network that makes IP-based restoration an effective and cost-efficient approach. The effectiveness of IP-based restoration is evaluated by analyzing network failure characteristics, and measuring disruptions in service availability during controlled failure experiments in the backbone. Current trends for improving the performance of IP-based restoration are also discussed.

Sprint long distance network survivability: today and tomorrow

The high reliability exhibited by the Sprint long distance network is the result of many interrelated factors. The network utilizes robust architectures, systems, and equipment to provide a reliable transport infrastructure. Redundant equipment, conservative synchronization, protected power, and other factors combine to form a dependable foundation. New architectures and systems are under development to meet the changing demands of customers. This article summarizes Sprint's current network reliability, and emerging demands and technology, and presents possible directions for the future Sprint network. Sprint selected the SONET four-fiber bidirectional line switched ring (4F BLSR) architecture for the vast majority of its transport network architecture. A 4F BLSR architecture requires four fibers, or four optical wavelengths of wave division multiplexing (WDM), to accommodate a work and protect path in each direction around a ring of network elements or add-drop multiplexers (ADMs).