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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Survivable Traffic Grooming With Path Protection At The Connection Level In Wdm Mesh Networks, Wang Yao, Byrav Ramamurthy
Survivable Traffic Grooming With Path Protection At The Connection Level In Wdm Mesh Networks, Wang Yao, Byrav Ramamurthy
School of Computing: Faculty Publications
Survivable traffic grooming (STG) is a promising approach to provide reliable and resource-efficient multigranularity connection services in wavelength-division-multiplexing (WDM) optical networks. In this paper, we study the STG problem in WDM mesh optical networks employing path protection at the connection level. Both dedicated-protection and shared-protection schemes are considered. Given network resources, the objective of the STG problem is to maximize network throughput. To enable survivability under various kinds of single failures, such as fiber cut and duct cut, we consider the general shared-risklink- group (SRLG) diverse routing constraints. We first resort to the integer-linear-programming (ILP) approach to obtain optimal solutions. …
Shared Risk Link Group (Srlg)-Diverse Path Provisioning Under Hybrid Service Level Agreements In Wavelength-Routed Optical Mesh Networks, Lu Shen, Xi Yang, Byrav Ramamurthy
Shared Risk Link Group (Srlg)-Diverse Path Provisioning Under Hybrid Service Level Agreements In Wavelength-Routed Optical Mesh Networks, Lu Shen, Xi Yang, Byrav Ramamurthy
School of Computing: Faculty Publications
The static provisioning problem in wavelength-routed optical networks has been studied for many years. However, service providers are still facing the challenges arising from the special requirements for provisioning services at the optical layer. In this paper, we incorporate some realistic constraints into the static provisioning problem, and formulate it under different network resource availability conditions.We consider three classes of shared risk link group (SRLG)-diverse path protection schemes: dedicated, shared, and unprotected. We associate with each connection request a lightpath length constraint and a revenue value. When the network resources are not sufficient to accommodate all the connection requests, the …
A Link Bundled Auxiliary Graph Model For Constrained Dynamic Traffic Grooming In Wdm Mesh Networks, Wang Yao, Byrav Ramamurthy
A Link Bundled Auxiliary Graph Model For Constrained Dynamic Traffic Grooming In Wdm Mesh Networks, Wang Yao, Byrav Ramamurthy
School of Computing: Faculty Publications
This paper addresses the two-layer dynamic traffic grooming problem in wavelength-division-multiplexed (WDM) mesh optical networks subject to resource constraints and the generalized wavelength continuity (GWC) constraint. The GWC constraint is a relaxed wavelength continuity constraint which incorporates various kinds of wavelength conversion capabilities that exist in optical networks. As an improvement over the existing layered auxiliary graph (layered-AG) approach which represents each wavelength separately in the auxiliary graph, we introduce a largely simplified link bundled auxiliary graph (LBAG) model and propose the SAG-LB method to find paths and assign wavelengths for new lightpaths subject to the GWC constraint.We propose the …
An Efficient Consistency Algorithm For The Temporal Constraint Satisfaction Problem, Berthe Y. Choueiry, Lin Xu
An Efficient Consistency Algorithm For The Temporal Constraint Satisfaction Problem, Berthe Y. Choueiry, Lin Xu
School of Computing: Faculty Publications
Dechter et al. [5] proposed solving the Temporal Constraint Satisfaction Problem (TCSP) by modeling it as a meta-CSP, which is a finite CSP with a unique global constraint. The size of this global constraint is exponential in the number of time points in the original TCSP, and generalized-arc consistency is equivalent to finding the minimal network of the TCSP, which is NP-hard. We introduce _AC, an efficient consistency algorithm for filtering the meta-CSP. This algorithm significantly reduces the domains of the variables of the meta-CSP without guaranteeing arc-consistency. We use _AC as a preprocessing step to solving the meta-CSP. We …
Geospatial Decision Support For Drought Risk Management, Steve Goddard, Sherri K. Harms, Stephen E. Reichenbach, Tsegaye Tadesse, William J. Waltman
Geospatial Decision Support For Drought Risk Management, Steve Goddard, Sherri K. Harms, Stephen E. Reichenbach, Tsegaye Tadesse, William J. Waltman
School of Computing: Faculty Publications
Drought affects virtually all regions of the world and results in significant economic, social, and environmental impacts. The Federal Emergency Management Agency estimates annual drought-related losses in the U.S. at $6–$8 billion, which is more than any other natural hazard. Congress enacted the Agricultural Risk Protection Act of 2000 to encourage the U.S. Department of Agriculture (USDA) Risk Management Agency (RMA) and farmers to be more proactive in managing drought risk. Through the NSF’s Digital Government Program, the USDA RMA is working with the University of Nebraska–Lincoln Computer Science and Engineering Department, National Drought Mitigation Center (NDMC), and High Plains …
Guest Editor’S Introduction: Ieee 2004 International Symposium On Software Testing And Analysis, Gregg Rothermel
Guest Editor’S Introduction: Ieee 2004 International Symposium On Software Testing And Analysis, Gregg Rothermel
School of Computing: Faculty Publications
The International Symposium on Software Testing and Analysis (ISSTA) is the leading research conference in software testing and analysis. ISSTA brings together academics, industrial researchers, and practitioners to present and discuss the most promising approaches for using testing and analysis to assess and improve software and the processes by which it is engineered.
ISSTA 2004 was held in at the Parker House Hotel in Boston, Massachusetts, July 11-14, 2004. On this occasion the conference was co-located with the 16th Computer- Aided Verification Conference (CAV 2004), with the two conferences sharing a day of sessions. The conference was also preceded by …
Survivable Lightpath Provisioning In Wdm Mesh Networks Under Shared Path Protection And Signal Quality Constraints, Xi Yang, Lu Shen, Byrav Ramamurthy
Survivable Lightpath Provisioning In Wdm Mesh Networks Under Shared Path Protection And Signal Quality Constraints, Xi Yang, Lu Shen, Byrav Ramamurthy
School of Computing: Faculty Publications
This paper addresses the problem of survivable lightpath provisioning in wavelength-division-multiplexing (WDM) mesh networks, taking into consideration optical-layer protection and some realistic optical signal quality constraints. The investigated networks use sparsely placed optical–electrical–optical (O/E/O) modules for regeneration and wavelength conversion. Given a fixed network topology with a number of sparsely placed O/E/O modules and a set of connection requests, a pair of link-disjoint lightpaths is established for each connection. Due to physical impairments and wavelength continuity, both the working and protection lightpaths need to be regenerated at some intermediate nodes to overcome signal quality degradation and wavelength contention. In the …
Leveraging User-Session Data To Support Web Application Testing, Sebastian Elbaum, Gregg Rothermel, Srikanth Karre, Marc Fisher Ii
Leveraging User-Session Data To Support Web Application Testing, Sebastian Elbaum, Gregg Rothermel, Srikanth Karre, Marc Fisher Ii
School of Computing: Faculty Publications
Web applications are vital components of the global information infrastructure, and it is important to ensure their dependability. Many techniques and tools for validating Web applications have been created, but few of these have addressed the need to test Web application functionality and none have attempted to leverage data gathered in the operation of Web applications to assist with testing. In this paper, we present several techniques for using user session data gathered as users operate Web applications to help test those applications from a functional standpoint. We report results of an experiment comparing these new techniques to existing white-box …
Dynamic Routing In Translucent Wdm Optical Networks: The Intradomain Case, Xi Yang, Byrav Ramamurthy
Dynamic Routing In Translucent Wdm Optical Networks: The Intradomain Case, Xi Yang, Byrav Ramamurthy
School of Computing: Faculty Publications
Translucent wavelength-division multiplexing optical networks use sparse placement of regenerators to overcome physical impairments and wavelength contention introduced by fully transparent networks, and achieve a performance close to fully opaque networks at a much less cost. In previous studies, we addressed the placement of regenerators based on static schemes, allowing for only a limited number of regenerators at fixed locations. This paper furthers those studies by proposing a dynamic resource allocation and dynamic routing scheme to operate translucent networks. This scheme is realized through dynamically sharing regeneration resources, including transmitters, receivers, and electronic interfaces, between regeneration and access functions under …