Feasibility issues in shortest-path routing with traffic flow split

In the Internet’s autonomous systems packets are routed on shortest paths to their destinations. A related problem is how to find an admissible traffic routing configuration using paths that can be generated by a system of weights assigned to IP links. This problem is NP-hard. It can be formulated as a mixed-integer program and attempted with a branch-and-cut algorithm if effective cuts (valid inequalities) can be derived. In this paper we discuss admissibility of shortest-path routing configurations represented by binary variables specifying whether or not a particular link is on a shortest path to a particular destination. We present a linear programming problem for testing routing admissibility and derive solutions of this problem which characterize non-admissible routing configurations

Optimizing Flow Thinning Protection in Multicommodity Networks with Variable Link Capacity

International audienceFlow thinning (FT) is a concept of a traffic routing and protection strategy applicable to communication networks withvariable capacity of links. In such networks, the links do not attain their nominal (maximum) capacity simultaneously, so in atypical network state only some links are fully available whereas on each of the remaining links only a fraction of itsmaximum capacity is usable. Every end-to-end traffic demand is assigned a set of logical tunnels whose total capacity isdedicated to carry the demand’s traffic. The nominal (i.e., maximum) capacity of the tunnels, supported by the nominal(maximum) link capacity, is subject to state-dependent thinning to account for variable capacity of the links fluctuating belowthe maximum. Accordingly, the capacity available on the tunnels is also fluctuating below their nominal levels and hence theinstantaneous traffic sent between the demand’s end nodes must accommodate to the current total capacity available onits dedicated tunnels. The related multi-commodity flow optimization problem is NP-hard and its noncompact linearprogramming formulation requires path generation. For that, we formulate an integer programming pricing problem, atthe same time showing the cases when the pricing is polynomial. We also consider an important variant of FT, affinethinning, that may lead to practical FT implementations. We present a numerical study illustrating traffic efficiency of FT andcomputational efficiency of its optimization models. Our considerations are relevant, among others, for wireless meshnetworks utilizing multiprotocol label switching tunnels

Link load balancing optimization of telecommunication networks: a column generation based heuristic approach

This paper deals with optimal load balancing in telecommunication networks. For a capacitated telecommunications network with single path routing and an estimated traffic demand matrix, we wish to determine the routing paths aiming at min-max optimization of link loads. To solve this problem, we propose a column (path) generation based heuristic. In the first step, we use column generation to solve a linear programming relaxation of the basic problem (obtaining a lower bound and a set of paths). In the second step, we apply a multi-start local search heuristic with path-relinking to the search space defined by the paths found in the first step. In order to assess the merits of this approach, we also implemented a search heuristic which is equivalent to the second step of the proposed one but with no constraints on the set of paths that can be used. Through a set of computational results, we show that the proposed heuristic is efficient in obtaining near optimal routing solutions within short running times. Moreover, the comparison of the two heuristics show that constraining the search space to the columns given by column generation gives better results since this solution space contains good quality solutions and, due to its size, enables to find them in short running times

Non-linear optimization for multi-path source routing in OBS networks

Optical Burst Switching (OBS) architectures without buffering capabilities are sensitive to burst losses. A proper routing strategy may help to reduce such congestion. In this letter we present a novel approach for OBS multi-path source routing problem. Our solution is based on non-linear optimization with a straightforward calculation of partial derivatives. Simulation results demonstrate that optimized routing effectively reduces the overall burst loss probability with respect to shortest path and deflection routing.Postprint (published version

Virtual topology design in OBS networks

The problem of burst losses in OBS networks has an impact on the service quality perceived by end users. In order to guarantee certain level of Service Quality (QoS) in terms of burst losses, wavelength resources have to be dimensioned properly. In this paper, we address the problem of the Virtual Topology (VT) design that concerns the establishment of explicit routing paths and the allocation of wavelengths in network links to support connections with QoS guarantees in the OBS network. We consider the GMPLS control plane as an overlying technology which facilitates the establishment of VT on top of physical network topology.Postprint (published version

Advanced Demand Response Solutions for Capacity Markets

International audience—The Internet of Things (IoT) paradigm brings an opportunity for advanced Demand Response (DR) solutions. Indeed, it enables visibility and control on the various appliances that may consume, store or generate energy within a home. It has been shown that a centralized control on the appliances of a set of households leads to efficient DR mechanisms; unfortunately, such solutions raise privacy and scalability issues. In this paper we propose an IoT-based DR approach that deals with these issues. Specifically, we propose and analyze a scalable two levels control system where a centralized controller allocates power to each house on one side and, each household implements an IoT-based DR local solution on the other side. A limited feedback to the centralized controller allows to enhance the performance with little impact on privacy. The solution is proposed for the general framework of capacity markets

Inter-Domain Path Computation using Improved Crankback Signaling in Label Switched Networks

The paper deals with the problem of finding suboptimal routing paths in multi-domain Internet environment. The proposed solution can be used in traffic enginering with MPLS

Telecommunication network design problems related to the notion of max-min fairness

to be adde

Network optimization techniques

This chapter is devoted to modeling and optimization techniques applicable to communication network design and planning. The main emphasis is put on the models dealing with optimization of the capacity of network resources and traffic routing that lead to tractable optimization problems. It is a common belief that the right means for such modeling are multicommodity flow networks (MFN). MFN form a field of operations research on its own, and are closely connected to integer programming. In consequence, the presented chapter aims at giving a systematic survey of basic MFN models and integer programming methods applicable to communication network design