M. Le Foll

Bio: M. Le Foll is an academic researcher from Orange S.A.. The author has contributed to research in topics: Routing protocol & Multiprotocol Label Switching. The author has an hindex of 1, co-authored 1 publications receiving 39 citations.

Survivable MPLS Over Optical Transport Networks: Cost and Resource Usage Analysis

Abstract: In this paper we study different options for the survivability implementation in MPLS over optical transport networks (OTN) in terms of network resource usage and configuration cost. We investigate two approaches to the survivability deployment: single layer and multilayer survivability and present various methods for spare capacity allocation (SCA) to reroute disrupted traffic. The comparative analysis shows the influence of the offered traffic granularity and the physical network structure on the survivability cost: for high bandwidth LSPs, close to the optical channel capacity, the multilayer survivability outperforms the single layer one, whereas for low bandwidth LSPs the single layer survivability is more cost-efficient. On the other hand, sparse networks of low connectivity parameter use more wavelengths for optical path routing and increase the configuration cost, as compared with dense networks. We demonstrate that by mapping efficiently the spare capacity of the MPLS layer onto the resources of the optical layer one can achieve up to 22% savings in the total configuration cost and up to 37% in the optical layer cost. Further savings (up to 9 %) in the wavelength use can be obtained with the integrated approach to network configuration over the sequential one, however, at the increase in the optimization problem complexity. These results are based on a cost model with different cost variations, and were obtained for networks targeted to a nationwide coverage

New Strategies for Connection Protection in Mixed-Line-Rate Optical WDM Networks

Abstract: Today's optical wavelength division multiplexing backbone networks need to support traffic demands with very diverse capacity requirements. Recent studies have shown how to design an optical transport network that supports mixed line rates (MLR), where the wavelength channels of the optical paths (i.e., lightpaths) can have a variety of capacities (10/40/100 Gbps). Some preliminary work on the design of MLR optical networks has already appeared, but survivability, which is a key concern in optical network design, is a nascent topic in MLR networks. This study investigates the problem of protection in MLR optical networks: in particular, we study how to design a cost-effective transparent MLR network that provides dedicated protection at the lightpath level. We propose three mechanisms: MLR-at-p-lightpath protection (MLR-p), MLR-at-lightpath protection (MLR-l), and MLR-with-backup-flow-grooming protection (MLR-g). The design problem is solved by two different approaches: (1) a two-step approach that formulates part of the problem as an integer linear program and (2) a heuristic approach. Our results show that, by appropriate assignment of rates to lightpaths, MLR networks can provide protection for diverse traffic demands with much lower transponder cost compared to single-line-rate networks.

IP/MPLS-over-OTN-over-DWDM Multilayer Networks: An Integrated Three-Layer Capacity Optimization Model, a Heuristic, and a Study

Abstract: Multilayer network design has received significant attention in current literature. Despite this, the explicit modeling of IP/MPLS over OTN over DWDM in which the OTN layer is specifically considered has not been addressed before. This architecture has been identified as promising that bridges integration and interaction between the IP and optical layers. In this paper, we present an integrated capacity optimization model for network planning of such multilayer networks that consider the OTN layer as a distinct layer with its unique technological sublayer constraints. We develop a heuristic algorithm to solve this model for large networks. Finally, we provide a detailed numeric study that considers various cost parameter values of each layer in the network. We analyze the impact of each layer's cost parameter values on neighboring layers and overall network cost.

Apparatus and method for determining optimum paths in a multi-layer network using a routing engine

Abstract: Network simulation equipment for determining routes across a multi-layer system, the network simulation equipment comprising: an adaptor module configured to convert a multi-layer system into a multi-layer network of nodes and links; a first routing engine configured to determine a plurality of populations of paths, each population of paths corresponding to a route across a layer of the multi-layer network; a second routing engine configured to determine a plurality of multi-layer populations of paths, each multi-layer population of paths corresponding to a route across the multi-layer network and comprising populations of paths for at least two different layers of the multi-layer network selected from the plurality of populations of paths determined by the first routing engine; and an evolving module configured to mate at least two multi-layer populations of paths from the plurality of multi-layer populations of paths to create a third multi-layer population of paths,

Multilayer Protection with Availability Guarantees in Optical WDM Networks

Abstract: Survivability is a key concern in modern network design. This paper investigates the problem of survivable dynamic connection provisioning in general telecom backbone networks, that are mesh structured. We assume differentiated services where connections may have different availability requirements, so they may be provisioned differently with protection (if needed) based on their availability requirements and current network state. The problem of effectively provisioning differentiated-service requests, that has been widely investigated for connections routed at the physical layer, assumes peculiar features if we consider sub-wavelength requests at the logical layer that have to be protected (or more generically, whose availability target has to be guaranteed), but also have to be groomed for an efficient use of network resources. An integrated multilayer approach is necessary that considers requirements and grooming of connections at the logical layer as well as their routing and availability at the physical layer. Joint availability-guaranteed routing and traffic grooming may lead to a negative interaction, since the objective of the first problem (guaranteeing a given level of availability to the connections) clashes with the objective of the other problem (minimizing resource consumption). For a multilayer WDM mesh network, we propose new multilayer routing strategies that perform effective availability-guaranteed grooming of sub-wavelength connections. These strategies jointly considers connection availability satisfaction and resource optimization and are developed under two different practical hypotheses: guaranteed target, i.e., a connection is routed only if its availability target is satisfied, and best-effort target, a connection is always routed and, when the availability target cannot be guaranteed, the path with the best possible availability is provisioned. Numerical results are reported and discussed for the two approaches mentioned above. In both cases, the results show high effectiveness of our provisioning strategy.

A Network Optimization Model for Multi-layer IP/MPLS over OTN/DWDM Networks

Abstract: The operational model for large Internet service providers is moving to a multi-layer architecture consisting of IP/MPLS coupled with OTN/DWDM. While there has been significant work on multi-layer networks, the explicit modeling in IP/MPLS over OTN/DWDM has not been addressed before. In this paper, we present a detailed network optimization model for the operational planning of such an environment that considers OTN as a distinct layer with defined restrictions.