Lina Battestilli

Dynamic scheduling of network resources with advance reservations in optical grids

Advance reservation of lightpaths in grid environments is necessary to guarantee QoS and reliability. In this paper, we have evaluated and compared several algorithms for dynamic scheduling of lightpaths using a flexible advance reservation model. The main aim is to find the best scheduling policy for a grid network resource manager that improves network utilization and minimizes blocking. The scheduling of lightpaths involves both routing and wavelength assignment. Our simulation results show that minimum-cost adaptive routing where link costs are determined by the current and future usage of the link provides the minimum blocking. For wavelength assignment, we have used a scheme that reduces fragmentation by minimizing unused gaps. We have also analyzed approaches for failure recovery and resource optimization.

EnLIGHTened Computing: An architecture for co-allocating network, compute, and other grid resources for high-end applications

Many emerging high performance applications require distributed infrastructure that is significantly more powerful and flexible than traditional grids. Such applications require the optimization, close integration, and control of all grid resources, including networks. The EnLIGHTened (ENL) computing project has designed an architectural framework that allows grid applications to dynamically request (in-advance or on-demand) any type of grid resource: computers, storage, instruments, and deterministic, high-bandwidth network paths, including lightpaths. Based on application requirements, the ENL middleware communicates with grid resource managers and, when availability is verified, co-allocates all the necessary resources. ENLpsilas domain network manager controls all network resource allocations to dynamically setup and delete dedicated circuits using generalized multiprotocol label switching (GMPLS) control plane signaling. In order to make optimal brokering decisions, the ENL middleware uses near-real-time performance information about grid resources. A prototype of this architectural framework on a national-scale testbed implementation has been used to demonstrate a small number of applications. Based on this, a set of changes for the middleware have been laid out and are being implemented.

Advance Reservation and Dynamic Scheduling of Point to Multipoint Lightpaths

Advance reservation is a technique employed so that a request is guaranteed 100% availability of the resource it applied for sometimes earlier. In this paper we introduce the concept of advance reservation of lightpaths for a certain request characterized by some source and multiple destinations and also the time when network resources are demanded. We first present a point to multipoint adaptive routing algorithm that forms the basis of establishing lightpaths. Then the lightpaths are in fixed on the route through a wavelength assignment technique that works along with an advance reservation scheme to ensure conflict resolution among incoming requests. Based on our algorithm, we run our simulation model to generate results and exemplify the fact that advance reservation outruns on-demand reservation as far as the blocking probability is concerned.

Edge-Reconfigurable Optical Networks (ERONs): Rationale, Network Design, and Evaluation

To bridge the gap between the current practice of setting up expensive, dedicated, lightpath connections (i.e., static topologies), and the distant future vision of inexpensive access to dynamically switched end-to-end lightpaths, we propose a medium term solution in the form of edge-reconfigurable optical networks (ERONs). An ERON is an overlay-control network created by installing readily available MEMS optical switches, and implementing a GMPLS control plane at sites interconnected by static lightpaths. The switches and control software are deployed at the edge of the network and operated by the organization-user (i.e., outside the network providers control), hence the term ldquoedge-reconfigurablerdquo. By providing dynamic, automated control of end-to-end lightpaths, ERONs enable the sharing of expensive network resources among multiple users and applications that require sporadic access to these resources. We develop an algorithm for creating an ERON from an existing topology of static lightpaths. We also present simulation results that quantify the benefits of ERONs, in terms of the number of lightpaths that are needed when compared to a static configuration of independent and dedicated circuits.

Burst lost probabilities in a queuing network with simultaneous resource possession: a single-node decomposition approach

An efficient analytical method is presented for the calculation of blocking probabilities in a tandem queuing network with simultaneous resource possession. This queuing network model is motivated from the need to model optical burst switching networks, where the size of the data bursts varies and the link distance between two adjacent network elements also varies depending on the networks topology. A fast single-node decomposition algorithm is developed to compute the blocking probabilities in the network. The algorithm extends the popular link-decomposition method from teletraffic theory by allowing dynamic simultaneous link possession. Simulation is used to validate the accuracy of the algorithm.

Generic optical network provisioning services to support emerging grid applications

Emerging high-end applications require a rich set of network provisioning services that go beyond the traditional source-destination, end-to-end path service. They also require high-bandwidth and high-quality circuit services that only optical networks could offer. In this paper, we first analyze some representative high-end Grid applications and abstract their needed generic set of network provisioning services. Then we provide some preliminary analysis on the routing, resource allocation, and survivability mechanisms of these generic network services. The focus is on the temporal and spatial extensions over the traditional network service definitions. We also introduce our implementation and experimental activities within the Enlightened Computing project and present ongoing research work.

Edge Reconfigurable Optical Network (ERON): Enabling dynamic sharing of static lightpaths

In this paper, we propose an edge reconfigurable optical network as an intermediate step toward fully dynamic optical core network. ERON is an overlay-control network created by installing GMPLS-enabled MEMs optical switches at the edge of a core optical network composed of static lightpaths. We propose a network design algorithm that takes as input the key resource locations dispersed globally and a realistic traffic matrix from end-users and outputs a virtual topology comprised of the minimum required static lightpaths interconnected via ERON switches. This paper describes the key concepts involved in the design of an efficient ERON network combined with routing and reservation algorithms to assure low blocking probabilities. We also describe the management and control architecture and protocols required to provide end-user/application control of the dynamic lightpaths.