Abstract

Postprint This paper describes an implementation, analysis and improvements to MATE (MPLS adaptive traffic engineering) algorithm. MATE is an on-line load balancing algorithm. As MATE was originally thought for constant average incoming traffic, the first improvement is the usage of an adaptive update step size for time varying traffic. The second one modifies the time interval between updates to adequate itself to the traffic characteristics and calculates the amount of measurements in each interval to have a reliable statistic. The original algorithm and the new version, which would be called MATE-TV (MATE for time-varying traffic), were implemented in a LINUX-MPLS network, using the 'mpls-linux' packet distributed by Source Forge.

Abstract

It is expected that IPv6 multihomed sites will obtain as many global prefixes as direct providers they have, so traffic engineering techniques currently used in IPv4 multihomed sites is no longer suitable. However, traffic engineering is required for several reasons, and in particular, for being able to properly support multimedia communications. In this paper we present a framework for traffic engineering in IPv6 multihomed sites with multiple global prefixes. Within this framework, we have included several tools such as DNS record manipulation and proper configuration of the policy table defined in RFC 3484. To provide automation in the management of traffic engineering, we analyzed the usage of two mechanisms to configure the policy table. This work has been partly supported by the European Union under the E-Next Project FP6-506869 and by the OPTINET6 project TIC-2003-09042-C03-01. Publicado

Abstract

In this paper, we compare two routing scenarios for grooming-capable optical-beared two-layer networks that are capable of meeting the Traffic Engineering (TE) objectives. The first one applies completely dynamic WDM layer that adapts instantly to all traffic changes. The second one is based on fixed WDM topology (“lower layer”). To achieve the best performance, the fixed lightpath system is optimized in advance according to the characteristics of the expected traffic. In both cases, the upper layer is assumed to be dynamic. We perform extensive simulations to compare these two multi-layer Routing and Traffic Engineering approaches that are currently both of particular practical interest with their inherent advantages and drawbacks.

Abstract

In this paper we study traffic engineering in Multiprotocol Label Switching (MPLS) networks. We consider off-line computation of disjoint working and restoration paths where path rerouting is used as the restoration scheme. We first compute maximum number of paths for each demand such that paths satisfy diversity requirements. Using the generated path set we study four different approaches for selecting working and restoration paths, and formulate each method as an Integer Linear Programming (ILP) problem. The first two methods treat working and restoration path design problems separately. We propose two new path design methods that jointly optimize the working and restoration paths. A traffic uncertainty model is developed in order to evaluate performances of these four approaches based on their robustness with respect to changing traffic patterns. We compare these design approaches based on the number of additional demands carried and the distribution of residual capacity over the network. It is shown through simulations that the weighted load balancing method proposed in this paper outperforms the other three methods in handling traffic demand uncertainty.

Abstract

In this paper we present a comprehensive set of mechanisms that restore to the site administrator the capacity of enforcing traffic engineering (TE) policies in a multiaddressed IPv6 scenario. The mechanisms rely on the ability of SHIM6 to securely perform locator changes in a transparent fashion to transport and application layers. Once an outgoing path has been selected for a communication by proper routing configuration in the site, the source prefix of SHIM6 data packets is rewritten by the site routers to avoid packet discarding due to ingress filtering. The SHIM6 locator preferences exchanged in the context establishment phase are modified by the site routers to influence in the path used for receiving traffic. Scalable deployment is ensured by the stateless nature of these mechanisms. Publicado

Abstract

International audience; The main ideas behind the design of CATS were to have a general purpose simulator able to be a stable basis for the development of other modules, representing different levels of Air Traffic Control and Air Traffic Management. The basic framework and hypothesis of the CATS simulator are introduced. Two approaches of automatic conflict resolution are detailed as examples. The first one deals with a centralized control system for high density areas and medium term (10 to 15 minutes ahead) control. The second one deals with an on board reactive short term (3 to 10 minutes ahead) automatic conflict solver. As both solvers use a conflict detection that is robust to uncertainties, a convex modeling of uncertainties is first introduced.

Abstract

International audience; This paper introduces two algorithms which allocate optimal separated 3D-trajectories to the main traffic flows. The first approach is a 1 vs. n strategy which applies an A* algorithm iteratively to each flow. The second is a global approach using a genetic algorithm, applied to a population of trajectory sets. The algorithms are first tried on a toy problem, and then applied to real traffic data, using operational aircraft performances. The cumulated costs of the trajectory deviations are used to compare the two algorithms.

Abstract

International audience; The increase in air traffic and the limited capacity of air traffic control services force us to think of a new way in which to control aircraft. An innovative ATM concept, called Sector-Less Air Traffic Management, has been defined by the Eurocontrol Experimental Centre. In this concept the role of the controller is radically different from the current one : instead of having controllers controlling a sector, controllers would be responsible for a certain number of aircraft from departure to arrival in terminal areas. The aim of this paper is to redesign the European en-route network in order to make this new way of controlling aircraft possible and to provide an aeroplane with the shortest route possible by providing a new route network. The approach proposed here is, starting from scratch, to provide a very simple route network and to improve it by using optimisation algorithm. A generated route network will be evaluated in terms of length of trajectories weighted by the amount of aeroplanes using them and then compare it with the direct route network and the current one. Using this tool and a fast time air traffic simulator, the Sector-Less concept will be able to be evaluated in terms of capacity and delay due to conflict. This also provides the route density of the network for this concept. The results of various simulations performed on the best route network generated so far will be presented.

Abstract

While many have advocated for the use of Virtual Local Area Networks (VLANs) as a way to provide scalable traffic management, finding the optimal traffic split (mapping) among VLANs to achieve load balancing has turned out to be a very challenging and combinatorially complex problem to solve. This paper considers the traffic engineering problem in data center networks by studying the joint problem of finding spanning trees for VLANs and optimally selecting the most promising spanning trees to map the traffic flows onto. We mathematically model this problem using Integer Linear Program (ILP) techniques and follow a primal-dual decomposition approach, using column generation, to solve exactly a relaxed mapping version of the problem, as well we present approximate solutions to the original problem. We show through numerical evaluations an outstanding scalability of the decomposed version of the problem and we use our results to study the performance of traffic engineering protocols developed in recent literature for data center networks. NPRP 5-137-2-045 grant from the Qatar National Research Fund (a member of the Qatar Foundation). Scopu