Adaptive wavelength routing in all-optical networks

Dynamic routing and wavelength assignment (RWA) is an attractive method for the efficient use of network resources in all-optical networks. We present a novel fixed alternate routing method referred to as Overlap-Degree Aware (ODA) routing in all-optical networks. A lot of researchers have focused on the shortest path routing and alternate shortest path routing taking into acount link and wavelength usage so as to reduce the consumption of network resources. The authors, however, believe that in order to minimize the blocking probability, it is important to consider not only the consumption of link and wavelength resources but also the existence of the other flows when a routing decision is made. The ODA routing decides routes using the knowledge of ingress-egress node pairs, and tries to prevent future path requests from being blocked unnecessarily by reserving link and wavelength resources for the future requests. Our simulation results show that our new routing algorithm outperforms Fixed-Alternate Routing (FAR) and Weighted Least Congestion Routing (WLCR) from the viewpoint of call blocking probability.

This paper studies the routing and wavelength assignment (RWA) problem in wavelength-routed all-optical networks with dynamic traffic demand. In this letter, we model the link state transition as a birth and death process. With the proposed Markov model, the path blocking probability can be determined based on the current link state and the potential link load information, and then, we establish lightpath on the least congested route. The simulation result shows that compared with other adaptive routing algorithms, the proposed algorithm achieves much better blocking performance.

In optical WDM networks, transmission of information along optical lines is advantageous since it has high transmission capacity, scalability, feasibility and also high reliability. But large amount of information is being carried; any problem during transmission can lead to severe damage to the data being carried. Hence it is essential to consider the routing as well as the wavelength assignment problems and then develop a combined solution for both the problems. In this paper, we propose to develop a routing and wavelength assignment algorithm for selecting the suitable alternate path for the data packets transmission. Two stages are based on the available bandwidth and the number of wavelength used in the link as construction of alternate paths, route and wavelength selection. In proposed work, Adaptive Routing and First-Fit Wavelength Assignment (AR-FFWA) algorithm to be used. For each pair of source and destination, the path with the minimum granularity values are selected as the primary path for data transmission, allocating the sufficient wavelength and the performances will be evaluated by using ns-2 simulation models. When we compared to existing system the overall blocking probability will be reduced to too low.

A theory for the design of deadlock-free adaptive routing algorithms for wormhole networks, proposed by the author (1991, 1993), supplies sufficient conditions for an adaptive routing algorithm to be deadlock-free, even when there are cyclic dependencies between channels. Also, two design methodologies were proposed. Multicast communication refers to the delivery of the same message from one source node to an arbitrary number of destination nodes. A tree-like routing scheme is not suitable for hardware-supported multicast in wormhole networks because it produces many headers for each message, drastically increasing the probability of a message being blocked. A path-based multicast routing model was proposed by Lin and Ni (1991) for multicomputers with 2D-mesh and hypercube topologies. In this model, messages are not replicated at intermediate nodes. This paper develops the theoretical background for the design of deadlock-free adaptive multicast routing algorithms. This theory is valid for wormhole networks using the path-based routing model. It is also valid when messages with a single destination and multiple destinations are mixed together. The new channel dependencies produced by messages with several destinations are studied. Also, two theorems are proposed, developing conditions to verify that an adaptive multicast routing algorithm is deadlock-free, even when there are cyclic dependencies between channels. As an example, the multicast routing algorithms of Lin and Ni are extended, so that they can take advantage of the alternative paths offered by the network.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Adaptive routing is widely regarded as a promising approach to improving interconnection network performance. Many designers of adaptive routing algorithms have used synthetic communication patterns, such as uniform and transpose traffic, to compare the performance of various adaptive routing algorithms with each other and with oblivious routing. These comparisons have shown that the average message latency is usually lower with adaptive routing. On the other hand, when a parallel program is executed on a multiprocessor the goal is to reduce the total execution time. We explain why improving the average message latency of a routing algorithm does not necessarily lead to a lower execution time for real applications. We support this observation by reporting simulation results for both adaptive and oblivious routing using communication derived from real applications. Specifically, we report the performance of various routing algorithms for directed acyclic graphs (DAGs) derived from the Cholesky factorization of sparse matrices. Our results show that there is little correlation between average message latency and the total execution time of a parallel program. Hence, average message latency does not seem to be a useful measure of the performance of a routing algorithm. This strongly suggests that current comparisons of routing algorithms do not provide a reliable indication of the performance improvements to be realized by executing programs on a multiprocessor with such a routing algorithm. We interpret these results and suggest several alternatives for further research.

In order to transmit data efficiently over an optical network, many routing and wavelength assignment (RWA) algorithms have been proposed. This work presents a genetic algorithm that aims at solving the RWA problem, which consists of choosing the most suitable lightpath (i.e., a combination of a route and a wavelength channel) between a source-destination pair of nodes in all-optical networks. A comparison to some already known approaches in terms of blocking probability was made. Results show a reasonable performance, since the average blocking probability achieved by the genetic algorithm was lower than or relatively equivalent to the standard approaches compared.

The hierarchical routing and wavelength assignment problem in Automatic Switched Optical Network (ASON) is researched. Based on our analysis, three adaptive algorithms called MLLR (Multi-Layer Least Loaded Routing Algorithm), WMLCR (Wavelength-graph-based Multi-Layer Least Congestion Routing Algorithm) and BMR (Backtracking-based Multi-Layer Routing Algorithm) are proposed. A platform named AHORSP (ASON based hierarchical optimal routing & signaling platform) supporting our routing scheme is proposed and demonstrated. The simulation shows that the proposed algorithms can have comprehensive application on the basis of their convenience to be realized, low BP performance and acceptable operation time.

This paper studies the routing and wavelength assignment (RWA) in wavelength-routed all optical Wavelength Division Multiplexing (WDM) networks. A conception named Link Multiplexing Degree is introduced in our research and a novel adaptive RWA algorithm named MinSum is proposed following our theory analysis. MinSum considers more network state information than other adaptive RWA algorithms while the calculation process is more reasonable. The simulation result shows that MinSum performs better than its counterparts and the network performance can be improved significantly by this novel algorithm.

In this paper we consider the routing and wavelength assignment problem in a wavelength routed all optical network. Inspired by techniques from artificial intelligence, in particular the Blocking Island (BI) abstraction, we propose a simple and intelligent routing and wavelength assignment (RWA) algorithm: BI_RWA. This algorithm can be used in arbitrarily connected optical networks. In addition, it is general enough such that with some simple modifications, it can be applied to different optical networking scenarios: static or dynamic traffic, single or multiple fiber links between node pairs, with or without wavelength converters. We have conducted simulation experiments to evaluate the performance of our algorithm. The simulation is carried out in two parts: static traffic and dynamic traffic. The results will demonstrate that our RWA algorithm outperforms state-of-the-art related algorithms.

We propose a dynamic routing and wavelength assignment algorithm in an all-optical network with limited-range wavelength conversions. For each randomly arrived request, the correlation of different wavelengths on different links in all possible routes is described by the wavelength weight in our algorithm. We try to assign wavelengths on each candidate route using a shortest-path algorithm based on the wavelength weight and choose the best as its route and wavelength assignment scheme. Numerical results obtained for NSFNET and a 12-node ring show that our algorithm can greatly reduce the blocking probability and the number of required conversions under uniform traffic or traffic dominated by larger hop routes.

In this paper, we have minimized the effects of failures on network performance, by using suitable Routing and Wavelenghth Assignment(RWA) method without disturbing other performance criteria such as blocking probability(BP) and network management(NM). The computation complexity is reduced by using Kalaman Filter(KF) techniques. The minimum reconfiguration probability routing (MRPR) algorithm must be able to select most reliable routes and assign wavelengths to connections in a manner that utilizes the light path(LP) established efficiently considering all possible requests.

Compressionless Routing (GR) is a new adaptive routing framework which provides a unified framework for efficient deadlock-free adaptive routing and fault-tolerance. CR exploits the tight-coupling between wormhole routers for flow control to detect potential deadlock situations and recover from them. Fault-tolerant Compressionless Routing (FCR) extends Compressionless Routing to support end-to-end fault-tolerant delivery. Detailed routing algorithms, implementation complexity and performance simulation results for CR and FCR are presented.CR has the following advantages: deadlock-free adaptive routing in torus networks with no virtual channels, simple router designs, order-preserving message transmission, applicability to a wide variety of network topologies, and elimination of the need for buffer allocation messages. FCR has the following advantages: tolerates transient faults while maintaining data integrity (nonstop fault-tolerance), tolerates permanent faults, can be applied to a wide variety of network topologies, and eliminates the need for software buffering and retry for reliability. These advantages of CR and FCR not only simplify hardware support for adaptive routing and fault-tolerance, they also can simplify communication software layers.

Due to Low-Rate Wireless Personal Area Networks(LR-WPANs) is popularly used in Internet of Things (IOT) in recent years, Chiu and Wang proposed a linked list routing algorithm with wormhole mechanism, which includes the linked list network construction mechanism, the wormhole mechanism and the MODBUS extension instructions for data collection. There are still a lot of non-adaptive problems in that algorithm, such that network initialization problem, continuous nodes broken problem and node outliers problem. Those problems could make the whole network stay in unstable state when the special conditions bring out. In this paper, we proposed an adaptive linked-list routing algorithm with wormhole mechanism. By proposed the Lock-address mechanism fundamentally, we can make the stable chain scission, reset sequentially and cutting timer determination mechanism for broken nodes. In simulation, the performance of network initialization of adaptive linked-list routing algorithm with wormhole mechanism and flooding is compared and simulated by NS3 in this paper. The simulations results reveal that the initialization of adaptive linked-list routing algorithm with wormhole mechanism is more efficient than flooding when nodes are 5 meters apart and a matrix model of nodes number from 7*7 to 15*15.

We present a model for designing wormhole routing algorithms that are deadlock free, livelock free, minimal or nonminimal, and maximally adaptive. A unique feature of this model is that it is not based on adding physical or virtual channels to network topologies (though it can be applied to networks with extra channels). Instead, the model is based on analyzing the directions in which packets can turn in a network and the cycles that the turns can form. Prohibiting just enough turns to break all of the cycles produces routing algorithms that are deadlock free, livelock free, minimal or nonminimal, and maximally adaptive for the network. In this paper, we focus on the two most common network topologies for wormhole routing,n-dimensional mesh, just a quarter of the turns must be prohibited to prevent deadlock. The remaining three quarters of the turns permit partial adaptiveness in routing. Partially adaptive routing algorithms are described for 2D meshes,n-dimensional meshes,k-aryn-cubes, and hypercubes. Simulations of partially adaptive and nonadaptive routing algorithms for 2D meshes and hypercubes show that which algorithm has the lowest latencies and highest sustainable throughput depends on the pattern of message traffic. For nonuniform traffic, partially adaptive routing algorithms perform better than non-adaptive ones.

We present two routing algorithms based on deflection and convergence, which are able to provide high bandwidth and an ending guarantee for the end-to-end delay in a core network. We study the performance of these routing techniques by using simulations, and we prove the bounds on the delay.