Abstract. We investigate new routing and wavelength assignment algorithms considering as constraints physical impairments that arise in transparent networks. Accounting both linear and nonlinear impairments we propose a scheme that integrates the routing and wavelength assignment to achieve an optimal combination of physical and networking performance. Through simulations of a typical long haul network the improvement achieved using the proposed approach compared to conventional RWA algorithms (i.e shortest path and first fit) is demonstrated and the significance of impairment aware routing and wavelength assignment schemes is recognized.

No abstract

No abstract

We present a framework for the alleviation of the main problems induced due to optical transparency based on the use of advanced optical performance monitoring, physical layer modeling tools, and new algorithms for routing. IntroductionWavelength division multiplexing (WDM) technology is a promising candidate for next-generation backbone optical networks. The rapidly increasing traffic demands are imposing the requirement for cost effective high capacity solutions that WDM networks can support. Optical networks can be either opaque performing optoelectronic conversions at every node or transparent in which the signals are transported end-to-end optically, without being converted to the electrical domain along their path. Another solution called managed reach networks has been proposed [1] and is a compromise between transparent and opaque networks where selective regeneration is used at specific network locations as needed in order to maintain acceptable signal quality from source to destination. This approach reduces the number of regenerators required compared to the case of opaque networks, but requires more complicated management and monitoring of the signal quality and resource allocation schemes.In WDM networks a control mechanism is required to establish and tear down optical connections, between source and destination nodes. This is known as connection provisioning and is achieved utilizing specific routing and wavelength assignment algorithms (RWA). The development of an intelligent control plane able to provide efficient connection provisioning is an important traffic engineering problem for minimizing the cost and improve the efficiency of resource utilization. The introduced intelligence will enable dynamic management of physical impairments, automatic topology discovery and enhance failure localization and network restoration.Optical networks evolve towards increased transparency in the physical layer and more intelligence in the control and management plane. The introduction of optical transparency (through elimination of OEO conversions and electronic processing), brings many benefits to the overall network performance. However, operating a transparent mesh optical network is extremely challenging. The network designer has to deal with a number of issues like a) the accumulation of signal impairments that deteriorate the signal quality and b) the inability to locate network element failures in order to provide efficient network restoration. To overcome the problems caused by the impairments at the physical layer, dynamic impairment management techniques may be implemented in-line (e.g. optical means of impairment compensation) or at the optical transponder interfaces (e.g. electronic mitigation of impairments). From the network layer view, the implementation of certain RWA algorithms that consider signal impairments and constraint the routing of wavelength channels according to the physical characteristics of the optical network paths can further improve the performance and minimize the blocking pr...

Optical packet switching (OPS) has been proposed as a strong candidate for future metro networks. This paper assesses the viability of an OPS-based ring architecture as proposed within the research project DAVID (Data And Voice Integration on DWDM), funded by the European Commission through the Information Society Technologies (IST) framework. Its feasibility is discussed from a physical-layer point of view, and its limitations in size are explored. Through dimensioning studies, we show that the proposed OPS architecture is competitive with respect to alternative metropolitan area network (MAN) approaches, including synchronous digital hierarchy, resilient packet rings (RPR), and star-based Ethernet. Finally, the proposed OPS architectures are discussed from a logical performance point of view, and a high-quality scheduling algorithm to control the packet-switching operations in the rings is explained. Index Terms-Optical packet switching, wavelength-division multiplexing, metropolitan area networks (MANs), performance, medium access control (MAC). I. INTRODUCTION D ESPITE the recent economic malaise, the demand for telecommunication services continues to grow steadily. Even though this growth may have been overenthusiastically acclaimed (leading to the creation and explosion of the "bubble"), it cannot be denied that telecommunication networks are at the Manuscript