A framework for tiered service in MPLS networks

Abstract — Many network operators offer some type of tiered service, in which users may select only from a small set of service levels (tiers). Such a service has the potential to simplify a wide range of core network functions, allowing the providers to scale their operations efficiently. In this work, we provide a theoretical framework for reasoning about and tackling algorithmically the general problem of service tier selection. Drawing upon results from discrete location theory, we formulate the problem as a p-median problem under a new directional distance measure, and we develop efficient algorithms for a number of important variants. Our main finding is that, by appropriately selecting the set of service levels, network providers may realize the benefits of tiered service with only a small sacrifice in network resources. I

Single-hop lightwave WDM networks and applications to distributed computing

Ph.D.Mostafa H. Amma

ABSTRACT ZEYDY ORTIZ-LAUREANO. Techniques to Support Multicast Traffic in Single-Hop

Many applications and telecommunications services in future high-speed networks will require some form of multipoint communication. The problems associated with providing network support for multipoint communication have been widely studied within a number of different networking contexts. As current network technologies evolve to an alloptical, largely passive infrastructure, these problems take on new significance and raise a number of challenging issues that require novel solutions. We consider the problem of supporting multipoint communication at the media access control (MAC) layer of broadcast-and-select Wavelength Division Multiplexed (WDM) networks. In this environment, bandwidth consumption and channel utilization arise as two conflicting objectives in the design of scheduling algorithms for multicast traffic. We present a new technique for the transmission of multicast packets which is based on the concept of a virtual receiver. This is a set of physical receivers which behave identically in terms of tuning. We focus on the problem of optimally selecting the virtual receivers, and prove that it is NP-complete. We then present four heuristics of varying degrees of complexity for obtaining virtual receivers that provide a good balance between the tw

An Efficient Algorithm for Solving Traffic Grooming Problems in Optical Networks

Abstract—We consider the virtual topology and traffic routing (VTTR) problem, a subproblem of traffic grooming that arises as a fundamental network design problem in optical networks. The objective of VTTR is to determine the minimum number of lightpaths so as to satisfy a set of traffic demands, and does not take into account physical layer constraints; a routing and wavelength assignment (RWA) algorithm must reconcile the virtual topology obtained by VTTR with the physical topology. We propose an efficient algorithms that uses a partial LP relaxation technique with lazy constraints to improve substantially the scalability of VTTR, and, hence, of traffic grooming. Our approach delivers a desirable tradeoff between running time and quality of the final solution. I

Scalable Optimal Traffic Grooming in WDM Rings Incorporating Fast RWA Formulation

We present a scalable formulation for the traffic grooming problem in WDM ring networks. Specifically, we modify the ILP formulation to replace the constraints related to routing and wavelength assignment (RWA), typically based on a link approach, with a new set of constraints based on the maximal independent set decomposition (MISD) that we recently developed to solve optimally the RWA problem in ring networks. Our experimental study indicates that the new formulation results in an improvement of up to two orders of magnitude in running time. Consequently, it is now possible to solve the traffic grooming problem to optimality for 16-node rings in a few seconds