Energy management in communication networks: a journey through modelling and optimization glasses

The widespread proliferation of Internet and wireless applications has produced a significant increase of ICT energy footprint. As a response, in the last five years, significant efforts have been undertaken to include energy-awareness into network management. Several green networking frameworks have been proposed by carefully managing the network routing and the power state of network devices. Even though approaches proposed differ based on network technologies and sleep modes of nodes and interfaces, they all aim at tailoring the active network resources to the varying traffic needs in order to minimize energy consumption. From a modeling point of view, this has several commonalities with classical network design and routing problems, even if with different objectives and in a dynamic context. With most researchers focused on addressing the complex and crucial technological aspects of green networking schemes, there has been so far little attention on understanding the modeling similarities and differences of proposed solutions. This paper fills the gap surveying the literature with optimization modeling glasses, following a tutorial approach that guides through the different components of the models with a unified symbolism. A detailed classification of the previous work based on the modeling issues included is also proposed

IDEALIST control and service management solutions for dynamic and adaptive flexi-grid DWDM networks

Wavelength Switched Optical Networks (WSON) were designed with the premise that all channels in a network have the same spectrum needs, based on the ITU-T DWDM grid. However, this rigid grid-based approach is not adapted to the spectrum requirements of the signals that are best candidates for long-reach transmission and high-speed data rates of 400Gbps and beyond. An innovative approach is to evolve the fixed DWDM grid to a flexible grid, in which the optical spectrum is partitioned into fixed-sized spectrum slices. This allows facilitating the required amount of optical bandwidth and spectrum for an elastic optical connection to be dynamically and adaptively allocated by assigning the necessary number of slices of spectrum. The ICT IDEALIST project will provide the architectural design, protocol specification, implementation, evaluation and standardization of a control plane and a network and service management system. This architecture and tools are necessary to introduce dynamicity, elasticity and adaptation in flexi-grid DWDM networks. This paper provides an overview of the objectives, framework, functional requirements and use cases of the elastic control plane and the adaptive network and service management system targeted in the ICT IDEALIST project

Multi-layer survivability in IP-over-WDM networks

Ph.DDOCTOR OF PHILOSOPH

Resource Allocation, and Survivability in Network Virtualization Environments

Network virtualization can offer more flexibility and better manageability for the future Internet by allowing multiple heterogeneous virtual networks (VN) to coexist on a shared infrastructure provider (InP) network. A major challenge in this respect is the VN embedding problem that deals with the efficient mapping of virtual resources on InP network resources. Previous research focused on heuristic algorithms for the VN embedding problem assuming that the InP network remains operational at all times. In this thesis, we remove that assumption by formulating the survivable virtual network embedding (SVNE) problem and developing baseline policy heuristics and an efficient hybrid policy heuristic to solve it. The hybrid policy is based on a fast re-routing strategy and utilizes a pre-reserved quota for backup on each physical link. Our evaluation results show that our proposed heuristic for SVNE outperforms baseline heuristics in terms of long term business profit for the InP, acceptance ratio, bandwidth efficiency, and response time

Lp-Based Flow-Rate Control And Modeling Of Capacity Collapse Propagation

The main focus of this thesis is to understand how congestion that is due to link failure propagates to successive upstream links, and how well the network maintains system flow under abnormal conditions. Alleviating network failures depends on how congestion propagates through the network. In general, units of trafï¬c can move from their origin to their destination quite rapidly, but the change in flow rates tends to propagate slowly. We develop novel capacity collapse propagation models that extends signiï¬cantly the concept of cell-transmission used to partition links into sections. The sampling is done in such a way that density wave propagates through a section of the link in one time interval. A general framework to model interaction between merging and diverging flow patterns is developed. The models considered for the nodes take into consideration the different types of intersections that may exist in the network. The capacity collapse propagation models can better represent networks with substantial propagation delay. The speed of the capacity collapse waves will be shown to depend on the magnitude of the failure. We integrate our models within the multicommodity flow framework, in which each commodity (origin-destination pair) uses k 2N link-disjoint paths to satisfy flow-rate demands. The congestion in the links is used to update the prices of the links, thus affecting the cost of travelling. We solve several minimum-cost linear-programming problems to control path flow-rate routing decisions triggered by the changes in the cost coefï¬cients. We conclude that proposed path flow-rate rerouting in response to the congestion in the links could contribute signiï¬cantly to network survivability. Numerical simulations of the proposed models are used to illustrate the concepts