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Proceedings of the 12th IEEE International Conference on High Performance Switching and Routing, HPSR 2011, 4-6 July 2011, Cartagena, Spain; 01/2011
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ABSTRACT: Emerging service grids are being challenged by an increasing number of jobs, larger job sizes, the demand for more storage and computational resources, and ever-rising bandwidth and latency requirements. A specific case of these grids, designed to administer highly demanding media applications (including media production environments) are the so-called media grids. Even though optical networking is the apparent technology of choice for high-bandwidth applications, the question arises whether current burst/packet and circuit switching solutions are flexible enough for the design and development of these next generation optical service grids. This paper introduces the concept of a media grid, deduces the requirements for such a grid. Furthermore, this paper proposes hybrid optical switching for the underlying network architecture, which is expected to substantially increase the overall system performance, compared to single-technology solutions.
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ABSTRACT: Cloud services based on datacenter networks are becoming very important. Optical networks are well suited to meet the demands set by the high volume of traffic between datacenters, given their high bandwidth and low-latency characteristics. In such networks, path protection against network failures is generally ensured by providing a backup path to the same destination, which is link-disjoint to the primary path. This protection fails to protect against disasters covering an area which disrupts both primary and backup resources. Also, content/service protection is a fundamental problem in datacenter networks, as the failure of a single datacenter should not cause the disappearance of a specific content/service from the network. Content placement, routing and protection of paths and content are closely related to one another, so the interaction among these should be studied together. In this work, we propose an integrated ILP formulation to design an optical datacenter network, which solves all the above-mentioned problems simultaneously. We show that our disaster protection scheme exploiting anycasting provides more protection, but uses less capacity, than dedicated single-link protection. We also show that a reasonable number of datacenters and selective content replicas with intelligent network design can provide survivability to disasters while supporting user demands.
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ABSTRACT: Recent years have demonstrated the limited scalability of electronic switching to realize transport networks. In response, all-optical switching has been identified as a candidate solution to enable high-capacity networking in the future. One of the fundamental challenges is to efficiently support a wide range of traffic patterns, and thus emerges the need for equipment that is both practical and economical to construct and deploy. We have previously proposed the use of multi-granular optical cross-connects (MG-OXC), which support switching on both the wavelength and sub-wavelength level. To this end, the MG-OXCs are equipped with cheap, highly scalable slow switching fabrics, as well as a small number of expensive fast switching ports. The goal of this work is two-fold: first to demonstrate that a small number of fast switching ports suffices to support a wide range of traffic requirements, and second that multi-granular optical switching can offer cost-benefits on a network-wide scale. The first objective is studied through simulation analysis of a single switching node, and results indicate that a limited number of fast switching ports can significantly improve burst blocking performance over slow only switches. Furthermore, under certain circumstances, the MG-OXC can even approach the performance of a fast only switch design. Secondly, we introduce an Integer Linear Programming model for the total network installation cost, and our evaluation indicates that multi-granular optical switching can be a cost-effective solution on the network level, in comparison to slow only or fast only approaches. Furthermore, we can achieve reduced costs of individual OXC nodes, which allows us to minimize scalability problems corresponding to emerging fast switching fabrics.
Optical Switching and Networking.
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ABSTRACT: In this paper, we discuss a use case for employing Grid technology in a media production/distribution environment. This type of environment is faced with the challenges of storing, retrieving and processing massive amounts of digital multimedia data in a reliable and highly performing manner, preventing Grid technology from being introduced in a straightforward way. We therefore propose the use of a MediaGrid framework, providing support for content/resource sharing and advanced collaborative working. This MediaGrid framework and its components are discussed in detail, and, since the proposed MediaGrid is tailored to the needs of media production/distribution companies, we introduce these companies’ profiles along with their typical user-task work flows, media application characteristics and service requirements. In order to experiment with various resource and topology setups and be able to develop and evaluate scheduling and QoS management algorithms that are tuned to the needs of these companies, we have developed MediaNSG, an advanced MediaGrid simulator which extends the ns-2 network simulator. MediaNSG’s inner workings are detailed and finally, some MediaNSG proof-of-concept simulations are presented.
Future Generation Computer Systems.
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ABSTRACT: Grids consist of the aggregation of numerous dispersed computational, storage and network resources, able to satisfy even the most demanding computing jobs. Due to the data-intensive nature of Grid jobs, there is an increasing interest in Grids using optical transport networks as this technology allows for the timely delivery of large amounts of data. Such Grids are commonly referred to as Lambda Grids.An important aspect of Grid deployment is the allocation and activation of installed network capacity, needed to transfer data and jobs to and from remote resources. However, the exact nature of a Grid’s network traffic depends on the way arriving workload is scheduled over the various Grid sites. As Grids possibly feature high numbers of resources, jobs and users, solving the combined Grid network dimensioning and workload scheduling problem requires the use of scalable mathematical methods such as Divisible Load Theory (DLT). Lambda Grids feature additional complexity such as wavelength granularity and continuity or conversion constraints must be enforced. Additionally, Grid resources cannot be expected to be available at all times. Therefore, the extra complexity of resilience against possible resource failures must be taken into account when modelling the combined Grid network dimensioning and workload scheduling problem, enforcing the need for scalable solution methods. In this work, we tackle the Lambda Grid combined dimensioning and workload scheduling problem and incorporate single-resource failure or unavailability scenarios. We use Divisible Load Theory to tackle the scalability problem and compare non-resilient lambda Grid dimensioning to the dimensions needed to survive single-resource failures. We distinguish three failure scenarios relevant to lambda Grid deployment: computational element, network link and optical cross-connect failure. Using regular network topologies, we derive analytical bounds on the dimensioning cost. To validate these bounds, we present comparisons for the resulting Grid dimensions assuming a 2-tier Grid operation as a function of varying wavelength granularity, fiber/wavelength cost models, traffic demand asymmetry and Grid scheduling strategy for a specific set of optical transport networks.
Future Generation Computer Systems.
