Optical burst switching is a promising solution for all-optical WDM networks. It combines the benefits of optical packet switching and wavelength routing while taking into account the limitations of the current all-optical technology. In OBS, the user data is collected at the edge of the network, sorted based on a destination address, and grouped into variable sized bursts. Prior to transmitting a burst, a control packet is created and immediately sent toward the destination in order to set up a bufferless optical path for its corresponding burst. After an offset delay time, the data burst itself is transmitted without waiting for a positive acknowledgment from the destination node. The OBS framework has been widely studied in the past few years because it achieves high traffic throughput and high resource utilization. However, despite the OBS trademarks such as dynamic connection setup or strong separation between data and control, there are many differences in the published OBS architectures. In this article we summarize in a systematic way the main OBS design parameters and the solutions that have been proposed in the open literature.The benefits of optical communication systems have been known for quite awhile, but it was not until the invention of wavelength-division multiplexing (WDM) that the potential of fiber was fully realized. The evolution of WDM optical networks can be classified as shown in Fig. 1, which is similar to the one presented by Gauger et al. [l]. Current WDM networks operate over point-to-point links, where optical-to-electrical-tooptical (OEO) conversion is required at each step. All future WDM designs, however, are focused on all-optical networks (AONs) where the user data travels entirely in the optical domain. The elimination of OEO conversion in AONs allows for unprecedented transmission rates. AONs can further be categorized as wavelength-routed networks (WRNs), optical burst switched networks (OBSNs), or optical packet switched networks (OPSNs). Also, each step of the optical evolution begins with a simpler ring design before moving on to the more general mesh topologies. In the following paragraphs we briefly outline the pros and cons of future all-optical architectures.The AON evolution begins with WRNs, whose operation consists of setting up circuit connections, called lightpaths, between the network nodes. The main constraint of WRNs, typical of all optical communications, is the limited number of wavelengths per fiber. In a larger WRN, for example, this scarce number of wavelengths makes it impossible to create a full mesh of lightpaths between all end users. Consequently, for each WRN topology, network architects have to solve the NP-hard problem of routing and wavelength allocation (RWA) of the lightpaths in order to optimally satisfy the desired user communication. The other challenge of WRNs is their quasi-static nature, which prevents them from efficiently supporting constantly changing user traffic. The proposed signaling protocol for WRNs is generalized multiprotocol la...
SUMMARYAdvance 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 fl exible advance reservation model. The main aim is to fi nd 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.
This paper describes innovative architectures and techniques for reserving and coordinating highly distributed resources, a capability required for many large scale applications. In the fall of 2006, Japan's G-lambda research team and the United States' EnLIGHTened Computing research team used these innovations to achieve the world's first inter-domain coordination of resource managers for in-advance reservation of network bandwidth and compute resources between and among both the US and Japan. The compute and network resource managers had different interfaces and were independently developed. Automated interoperability among the resources in both countries was enabled through various Grid middleware components. In this paper, we describe the middleware components, testbeds, results, and lessons learned.
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 (inadvance 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. ENL's 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.
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