Abstract

Logistic Service Providers (LSPs) offering hinterland transportation face the trade-off between efficiently using the capacity of long-haul vehicles and minimizing the first and last-mile costs. To achieve the optimal trade-off, freights have to be consolidated considering the variation in the arrival of freight and their characteristics, the applicable transportation restrictions, and the interdependence of decisions over time. We propose the use of a Markov model and an Approximate Dynamic Programming (ADP) algorithm to consolidate the right freights in such transportation settings. Our model incorporates probabilistic knowledge of the arrival of freights and their characteristics, as well as generic definitions of transportation restrictions and costs. Using small test instances, we show that our ADP solution provides accurate approximations to the optimal solution of the Markov model. Using larger problem instances, we show that our modeling approach has significant benefits when compared to common-practice heuristic approaches. Document type: Part of book or chapter of book

Abstract

Multiprotocol Label Switching (MPLS) is an emerging Internet technology that facilitates traffic engineering in service provider networks. This paper considers a network performance optimization problem related to traffic engineering over MPLS. We investigate the issue of dynamic partitioning of MPLS ingress traffic into several parallel Label Switched Paths (LSP). Specifically, we present a stochastic framework for the traffic partitioning problem. Within this framework, a set of parallel edge disjoint LSPs is modeled by parallel queues and a partitioning algorithm is devised for different service classes that is adaptive to the prevailing state of the network. The performance of this approach is illustrated by numerical examples. Document type: Part of book or chapter of book

Abstract

The problem of finding multi-constrained paths has been addressed by several QoS routing algorithms. While they generally satisfy the application requirements, they often do not consider the perspective of service providers. Service providers aim at maximizing the throughput and the number of accepted requests. These goals have been addressed by traffic engineering algorithms considering bandwidth as the sole application requirement. We propose a proper length function for an existing QoS routing algorithm (SAMCRA) that attempts to optimize network utilization while still offering QoS guarantees. This paper presents a comparison between several proposed algorithms via simulation studies. The simulations show that SAMCRA with a proper length performs similarly or even better than the best among the other algorithms and it has a fast running time. Document type: Part of book or chapter of book

Abstract

The transformation of the Internet into an important and ubiquitous commercial infrastructure has not only created rapidly rising bandwidth demands but also significantly changed consumer expectations in terms of performance, security and services. Consequentially as service providers attempt to encourage business and leisure applications on to the Internet, there has been a requirement for them to develop an improved IP network infrastructure in terms of reliability and performance [1]. Interest in congestion control through traffic engineering has arisen from the knowledge that although sensible provisioning of the network infrastructure is needed together with sufficient underlying capacity, these are not sufficient to deliver the QoS required [2]. This is due to dynamic variations in load. In operational IP networks, it has been difficult to incorporate effective traffic engineering due to the limited capabilities of the IP technology. In principle, Multiprotocol Label Switching (MPLS), a connection-oriented label swapping technology, offers new possibilities in addressing the limitations by allowing the operator to use sophisticated traffic control mechanisms.\r \r However, as yet, the traffic engineering capabilities offered by MPLS have not been fully exploited. Once label switched paths (LSPs) have been provisioned through the service providers' network, there are currently no management facilities for dynamic re-optimisation of traffic flows. The service level agreements (SLAs) between the network operator and the customer are agreed in advance of the commencement of traffic flow, and these are mapped to particular paths throughout the provider's domain and may be maintained for the duration of the contract. During transient periods, the efficiency of resource allocation could be increased by routing traffic away from congested resources to relatively under-utilised links. Some means of restoring the LSPs to their original routes once the transient congestion has subsided is also desirable. Document type: Part of book or chapter of book

Abstract

Part 21: Mobility and Logistics; International audience; Throughout the world societies are changing, so is mobility behavior. People are increasingly using multiple modes of transport; not only different modes for different trips but also combined use of different modes within one trip can be observed. Furthermore decisions for certain modes on specific trip stages depend on situational context (e.g. current traffic) and individual preferences. This trend can be supported by collaboration of mobility and service providers. Therefore information systems need to provide real-time data about traffic, provider status (of several mobility providers) and possible transfer points to enact context sensitive route adjustment. Alongside with customer preferences traffic flow can be optimized on individual and public level. In this article we strive to highlight challenges associated to this scenario. In addition we will present an architecture for intermodal information systems that offers services for individual planning, real-time route adjustment and provider cooperation. Document type: Part of book or chapter of book