George N. Rouskas

Bio: George N. Rouskas is an academic researcher from North Carolina State University. The author has contributed to research in topics: Traffic grooming & Network topology. The author has an hindex of 44, co-authored 251 publications receiving 7294 citations. Previous affiliations of George N. Rouskas include King Abdulaziz University & Georgia Institute of Technology.

Techniques for optical packet switching and optical burst switching

Abstract: Wavelength-division multiplexing appears to be the solution of choice for providing a faster networking infrastructure that can meet the explosive growth of the Internet. Several different technologies have been developed so far for the transfer of data over WDM. We survey two new technologies which are still in the experimental stage-optical packet switching and optical burst switching-and comment on their suitability for transporting IP traffic.

Traffic grooming in WDM networks: past and future

Abstract: Traffic grooming refers to techniques used to combine low-speed traffic streams onto high-speed wavelengths in order to minimize the networkwide cost in terms of line terminating equipment and/or electronic switching. Such techniques become increasingly important for emerging network technologies, including SONET/WDM rings and MPLS/MP/spl lambda/S backbones, for which traffic grooming is essential. In this article we formally define the traffic grooming problem, and we provide a general formulation that captures the features of a wide range of problem variants. We then present a comprehensive comparative survey of the literature that unveils the significant amount of research on this subject (the traffic grooming past). We also offer a broad set of ambitious research directions (the traffic grooming future) that are motivated by the exciting new challenges arising with the advent of MP/spl lambda/S technology.

A Survey of Virtual Topology Design Algorithms for Wavelength Routed Optical Networks

Abstract: In the past few years, there has been growing interest in wide area ``All Optical Networks'''' with {\em wavelength division multiplexing\/} (WDM), using {\em wavelength routing}. Due to the huge bandwidth inherent in optical fiber, and the use of WDM to match user and network bandwidths, the wavelength routing architecture is an attractive candidate for future backbone transport networks. A {\em virtual topology\/} over a WDM WAN consists of clear channels between nodes called {\em lightpaths}, with traffic carried from source to destination without electronic switching ``as far as possible'''', but some electronic switching may be performed. Virtual topology design aims at combining the best of optical switching and electronic routing abilities. Designing a virtual topology on a physical network consists of deciding the lightpaths to be set up in terms of their source and destination nodes and wavelength assignment. In this survey we first describe the context and motivations of the virtual topology design problem. We provide a complete formulation of the problem, describe and compare the formulations and theoretical results as well as algorithms, heuristics and some results in the current literature in the field. The reconfigurability issue, which is another attractive characteristic of optical networks, is also discussed and the literature surveyed. This survey is restricted to transport networks with wavelength routing. Similar virtual topology problems also arise in multihop broadcast local area optical networks, but this work does not directly apply to them and corresponding literature is not included in this survey. This survey also relates to the design of a static topology, not one in which individual lightpaths are set up and torn down in response to traffic demand.

Multicast routing with end-to-end delay and delay variation constraints

Abstract: We study the problem or constructing multicast trees to meet the quality of service requirements of real-time interactive applications operating in high-speed packet-switched environments. In particular, we assume that multicast communication depends on: (1) bounded delay along the paths from the source to each destination and (2) bounded variation among the delays along these paths. We first establish that the problem of determining such a constrained tree is NP-complete. We then present a heuristic that demonstrates good average case behavior in terms of the maximum interdestination delay variation. The heuristic achieves its best performance under conditions typical of multicast scenarios in high speed networks. We also show that it is possible to dynamically reorganize the initial tree in response to changes in the destination set, in a way that is minimally disruptive to the multicast session.

JumpStart: a just-in-time signaling architecture for WDM burst-switched networks

Abstract: We present an architecture for a core dWDM network which utilizes the concept of optical burst switching coupled with a just-in-time signaling scheme. It is a reservation-based architecture whose distinguishing characteristics are its relative simplicity, its amenability to hardware implementation, and the ability to support multicast natively. Another important feature is data transparency-the network infrastructure is independent of the format of the data being transmitted on individual wavelengths. We present the signaling protocol designed for this architecture, as well as an unified signaling message structure to be used in conjunction with the protocol. We also present the future directions of this research.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Optical burst switching (OBS) - a new paradigm for an optical Internet

Abstract: To support bursty traffic on the Internet (and especially WWW) efficiently, optical burst switching (OBS) is proposed as a way to streamline both protocols and hardware in building the future generation Optical Internet. By leveraging the attractive properties of optical communications and at the same time, taking into account its limitations, OBS combines the best of optical circuit-switching and packet/cell switching. In this paper, the general concept of OBS protocols and in particular, those based on Just-Enough-Time (JET), is described, along with the applicability of OBS protocols to IP over WDM. Specific issues such as the use of fiber delay-lines (FDLs) for accommodating processing delay and/or resolving conflicts are also discussed. In addition, the performance of JET-based OBS protocols which use an offset time along with delayed reservation to achieve efficient utilization of both bandwidth and FDLs as well as to support priority-based routing is evaluated.

Routing, Flow, And Capacity Design In Communication And Computer Networks

Abstract: In network design, the gap between theory and practice is woefully broad. This book narrows it, comprehensively and critically examining current network design models and methods. You will learn where mathematical modeling and algorithmic optimization have been under-utilized. At the opposite extreme, you will learn where they tend to fail to contribute to the twin goals of network efficiency and cost-savings. Most of all, you will learn precisely how to tailor theoretical models to make them as useful as possible in practice. Throughout, the authors focus on the traffic demands encountered in the real world of network design. Their generic approach, however, allows problem formulations and solutions to be applied across the board to virtually any type of backbone communication or computer network. For beginners, this book is an excellent introduction. For seasoned professionals, it provides immediate solutions and a strong foundation for further advances in the use of mathematical modeling for network design. (Less)

An overview of quality of service routing for next-generation high-speed networks: problems and solutions

Abstract: The upcoming gigabit-per-second high-speed networks are expected to support a wide range of communication-intensive real-time multimedia applications. The requirement for timely delivery of digitized audio-visual information raises new challenges for next-generation integrated services broadband networks. One of the key issues is QoS routing. It selects network routes with sufficient resources for the requested QoS parameters. The goal of routing solutions is twofold: (1) satisfying the QoS requirements for every admitted connection, and (2) achieving global efficiency in resource utilization. Many unicast/multicast QoS routing algorithms have been published, and they work with a variety of QoS requirements and resource constraints. Overall, they can be partitioned into three broad classes: (1) source routing, (2) distributed routing, and (3) hierarchical routing algorithms. We give an overview of the QoS routing problem as well as the existing solutions. We present the strengths and weaknesses of different routing strategies, and outline the challenges. We also discuss the basic algorithms in each class, classify and compare them, and point out possible future directions in the QoS routing area.