The ever-growing complexity of communication networking has been enhanced by the huge capacity of optical
networks, raising the need for new architectures. The WDM layer is now asked to be aware of emerging limitations of
the physical layer and QoS requirements of the upper layers. This situation suggests that at least part of the network be
designed for self-organization. The paper discusses the merits of swarm intelligence, and especially Ant Colony
Optimization, to support a self-organized control plane of an optical network.
This work aims to show the possibility of WDM optical network planning using the virtual topology. For this analysis,
heuristics methods were applied to take current and future traffic into account to plan a network under limited link
capacity. The results suggest that it is feasible to preserve enough open capacity to avoid blocking of future traffic,
without network disruption, allocating appropriate link capacities for a given planning period.
The paper introduces a new analytical approach for estimating blocking probabilities in all-optical networks. The assumptions of the classical Lee approximation are discussed and their effects are evaluated. The paper proposes a better substitute for the independent link assumption. The new assumption takes all active paths, as well as all free links, as independent objects on the network topology. The new model is shown to generate estimates that fit exactly the blocking probabilities obtained through simulations on linear topologies using Poissonian, spatially homogeneous traffic. An extension to regular meshes is presented that is asymptotically good for very small and very large nodal degrees. Finally, the independent wavelength assumption is also evaluated for two different wavelength assignment algorithms.
In this paper we develop an analytical model for the FIFO delay-line buffer in asynchronous optical networks with any packet length distribution, under the assumption that arrivals are Poissonian. We consider that the incoming traffic is distributed among an infinite number of inputs (Aloha traffic) and show that this consideration represents very suitably a real system. The model enables the exact calculation of packet loss probability and average delay, which makes it a very powerful tool for performance evaluation and planning/dimensioning of networks that use this kind of contention resolution technique. The buffer performance as predicted by the model is compared with simulations and discussed for some packet length distributions.
Traditional approaches to wavelength routing network design divide it into two separate problems: virtual topology design (VTD), in which best connections among nodes are derived from traffic demand, generating requests for connections; and routing-and-wavelength assignment (RWA), in which physical paths are accommodated in the physical topology to support the requested connections. This separation is necessitated by complexity, but it is suboptimal and will only yield the best static solution. For the case of dynamic traffic, one needs to set up a connection for each request as it arrives, and the lightpath is released after some finite amount of time. The routing and wavelength assignments must then preserve enough open capacity to avoid blocking of future requests. Several algorithms have been proposed for this purpose. We consider a loose topology, in which static and dynamic traffic demands share the physical resources of the network. For this purpose, the static assignment problems (VTD and RWA) are solved so that blocking probability is minimized for the dynamic traffic while minimum performance objectives are met for the static demand. The proposed strategy entails the use of the dynamic RWA heuristics to guide the solution of the static VTD/RWA problem.
In this paper a study of the design of wide area optical networks is presented, more specifically the problem of design of the virtual topology in optical networks. A network with a small number of nodes was analyzed through a Mixed-Integer Linear Programming formulation for the problem of the virtual topology design. Heuristic methods were then applied for a hypothetical optical network with a larger number of nodes plausibly located on the Brazilian territory. The work resulted in some suggested guidelines for the design of virtual topologies.
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