In this paper we study the benefits of wavelength translation in all-optical networks providing clear channel circuit-switching among users. We first establish approximate analytical models for a static-routing circuit-switched network with an arbitrary topology, both with and without wavelength translation. We then study the performance of the non-blocking centralized switch, the mesh-torus network and the ring network, using the analytical models and simulation results. It is shown that the analytical models match the simulation results very well in the case of the centralized switch and the mesh network. The results of our study also show that the benefits of wavelength translation are modest for the centralized switch and the ring network. On the other hand, the results show that wavelength translation can significantly improve the performance of a large mesh-torus network. 1 Introduction An all-optical network based on wavelength division multiplexing (WDM) and wavelength routing...

Wavelength division multiplexing technology is emerging as the transmission and switching mechanism for future optical mesh networks. In these networks, it is desired that a wavelength can be routed without electrical conversions. Two technologies are possible for this purpose: Wavelength Selective Cross-Connects (WSXC), and Wavelength Interchanging Cross-Connects (WIXC) which involve wavelength conversion. It is believed that wavelength converters may improve the blocking performance, but there is a mix of results in the literature on the amount of this performance enhancement. In this paper, we use two metrics to quantify the wavelength conversion gain: the reduction in blocking probability and the increase in maximum utilization, compared to a network without converters. We study effects of wavelength routing and selection algorithms on these measures for mesh networks. We use the Overflow Model to analyze the blocking probability for wavelength selective mesh networks using the Fir...

. Motivated by the problem of efficient routing in all-optical networks, we study a constrained version of the bipartite edge coloring problem. We show that if the edges adjacent to a pair of opposite vertices of an L-regular bipartite graph are already colored with ffL different colors, then the rest of the edges can be colored using at most (1+ff=2)L colors. We also show that this bound is tight by constructing instances in which (1 + ff=2)L colors are indeed necessary. We also obtain tight bounds on the number of colors that each pair of opposite vertices can see. Using the above results, we obtain a polynomial time greedy algorithm that assigns proper wavelengths to a set of requests of maximum load L per directed fiber link on a directed fiber tree using at most 5=3L wavelengths. This improves previous results of [9, 7, 6, 10]. We also obtain that no greedy algorithm can in general use less than 5=3L wavelengths for a set of requests of load L in a directed fiber tree, and thus t...

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This paper describes an architecture for adding an underlying wavelength-routed optical layer to a standard ATM network. The optical layer provides reconfigurable lightpaths that serve as links between electronic ATM switches. A lightpath is carried on a particular wavelength and path in the underlying optical wavelength-routed network. This work focuses on the mechanisms for controlling the optical layer. Distributed control protocols are provided for setting up and taking down lightpaths reliably and for updating the topology of the network, including the lightpaths. These protocols allow lightpath originators to obtain resources with high probability by minimizing reservation conflicts, allow lightpaths to stay up even if controllers along the path in the network fail, ensure that controllers in the network have a consistent view of the state of each lightpath, and ensure that all resources taken up by a lightpath are released once the lightpath is taken down. 1 Introduction We con...

In this paper we study the benefits of wavelength translation in all-optical networks providing clear channel circuit-switching among users. We first establish approximate analytical models for a static-routing circuit-switched network with an arbitrary topology, both with and without wavelength translation. We then study performance of the non-blocking centralized switch, the mesh-torus network and the ring network, using the analytical models and simulation results. It is shown that the analytical models match the simulation results very well in the case of the centralized switch and the mesh network. The results of our study also show that the benefits of wavelength translation are marginal for the centralized switch and the ring network. On the other hand, the results show that wavelength translation can significantly improve performance of a large mesh network. 1 Introduction An all-optical network based on wavelength division multiplexing (WDM) and wavelength routing appears to ...

This paper describes an architecture for controlling a wavelength-routed optical network. The optical network provides reconfigurable connections that can be used to carry different types of data, at possibly different bit rates. A connection consists of a path in the network and a wavelength on each link in that path. This work focuses on the mechanisms for controlling the optical connections. Distributed control protocols are provided for setting up and taking down connections reliably. These protocols allow connection originators to obtain resources with high probability by minimizing reservation conflicts, allow connections to stay up even if controllers along the path in the network fail, ensure that controllers in the network have a consistent view of the state of each connection, and ensure that all resources taken up by a connection are released once the connection is taken down. Fast protocols are also proposed for handling link failures and wavelength failures on a link. Thes...

. We address the issue of efficiently assigning wavelengths to communication requests in wavelength division multiplexing (WDM) optical networks. We consider directed tree and tree of rings topologies. These are topologies of concrete practical relevance for which undirected underlying graph models have been studied by Raghavan and Upfal [6]. Directed models were first studied by Mihail et al [4]. For trees, we give a polynomial time routing algorithm that, for requests of maximum load L per directed fiber link, uses at most 7=4L wavelengths. This improves the bound of Mihail et al.. As a corollary we also give an algorithm for trees of rings that uses 7=2L wavelengths. 1 Introduction Optics is a major technology that drives very high speed networking to the future. A single optical wavelength supports rates of gigabits-per-second (which in turn support multiple channels of voice, data, and video [3] [5]). Multiple laser beams that are propagated over the same fiber on distinct optica...

Wavelength division multiplexed point-to-point transport is becoming commonplace in wide area networks. With the expectation that the next step is end-to-end networking of wavelengths (in the optical domain, without conversion to electronics), there is a need for new design techniques, a new understanding of the performance issues, and a new performance evaluation methodology in such networks. This paper describes approaches to that end, summarizes research results, and points to open problems. 1 Introduction Wavelength Division Multiplexing (WDM), also known as Optical Frequency Division Multiplexing, is the use of multiple wavelengths to transmit different data streams. It is similar to Frequency Division Multiplexing (FDM), except in WDM, channel spacings are vastly larger than the information bandwidth of the signal. WDM is attractive since the same fiber can be employed for multiple data streams, saving costs on fiber and installation. Since an enormous bandwidth is available on f...

This paper examines the relative importance of wavelength conversion and timeslot interchange in improving the performance of multiwavelength time-division multiplexed networks. It is shown that, in networks with a small number of wavelengths, each carrying a large number of time-division multiplexed channels, significant performance improvements are achieved by the introduction of time-slot interchange alone, without wavelength conversion. However, some performance improvements are also achieved by the introduction of wavelength conversion alone