共查询到19条相似文献,搜索用时 343 毫秒
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本文研究了多光纤波分复用光网络中的动态路由和波长分配问题,提出了基于分层图模型的一种新的多光纤网络的动态路由优化算法,该算法将连接请求的建立转化为在分层图模型中为该请求寻找一条最优路径,这使得设计者可以同时考虑路由和波长分配的问题,从而取得更好的效果。模拟结果显示基于分层图模型的(MFD—RWA:MultiFiber Dynamic:Routing and Wavelength Assignment)算法优于传统的动态最短路径算法。 相似文献
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本文研究了多光纤波分复用光网络中的动态路由和波长分配问题,提出了基于分层图模型的一种新的多光纤网络的动态路由优化算法,该算法将连接请求的建立转化为在分层图模型中为该请求寻找一条最优路径,这使得设计者可以同时考虑路由和波长分配的问题,从而取得更好的效果。模拟结果显示基于分层图模型的(MFD-RWA:Multi-Fiber Dynamic Routing and Wavelength Assigrment)算法优于传统的动态最短路径算法。 相似文献
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随着科学技术的不断发展,光通信网络成为了网络技术的主要发展趋势,逐渐在通信网络中发挥出显著作用.现阶段,光通信网络中的光网络主要采用基于密集波分复用技术组成,一旦波分数量增加,光网络中的路由选择与波长分配问题就难以解决.本文详细阐述了分层图模型的概念,提出波长可变光网络中的动态RWA算法,并在此基础上分析了动态RWA算法的数值模拟,以在提高波长资源利用率的同时,降低网络阻塞率. 相似文献
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针对WDM光网络多播动态路由分配问题,提出了一种多约束条件下的路由分配算法.对WDM光网络中的多约束因素进行了系统分析,阐述了算法的实现步骤,并对CERNET和NSFNET两种网络进行了仿真实验和对比. 相似文献
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基于在波长可变光网络中的波长分层图模型,本文提出了一种在动态业务情况下的支持不同QoS要求的路由波长分配算法,根据客户层业务不同的QoS要求,通过分层图模型中参数的不同取值,对其光路建立请求区别对待,提供不同级别的光路建立.仿真结果表明该算法具有很好的性能,提高了全网的资源利用率,满足了客户层业务在建立光通路时不同的QoS要求对网络阻塞率的要求. 相似文献
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目前网络承载业务的趋势是以IP为中心的数据业务,从而促进了以WDM光网络向高速和宽带多波长的应用和普及,为了进一步提高网络的性能并提高资源利用率,出现了光网络控制面技术.路由选择与波长分配问题是WDM光传输网络控制面中非常重要的问题之一.目前实际应用最广泛的波长分配算法是First-Fir(FF)算法.本文基于FF算法,研究动态业务下波分复用光网络在固定选路下的波长分配问题,提出了一种新的波长分配启发式算法——Joint First Fit.计算机仿真试验表明,与常用的FF算法相比,该算法显著的降低了网络呼叫阻塞率,有利于提高网络资源的利用率. 相似文献
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Priority-based minimum interference path multicast: routing algorithm in optical virtual private network 总被引:1,自引:0,他引:1
Sang-Bo Seo Seung-Mi Song Sung-Un Kim Bong-Kee Sin 《Photonic Network Communications》2009,18(3):265-274
While the “Virtual Private Network (VPN) over Internet” is cost-effective and flexible, it suffers from the difficulty of
providing adequate transmission capacity for high bandwidth services. Hence a Dense Wavelength Division Multiplexing (DWDM)
based “Optical VPN (OVPN)” technology has been regarded as a good alternative for realizing the future VPN services. To improve
the transparency and data rate of OVPN, it is critical to consider the problem of Routing and Wavelength Assignment (RWA)
for transmission capacity utilization. This paper proposes a Priority-based Minimum Interference Path Multicast Routing (PMIPMR)
algorithm, a new routing algorithm which finds alternative routes based on node priorities and Virtual Source (VS) nodes that
has both splitting and wavelength conversion, and then chooses a path that does not interfere with potential future multicast
session requests when congestions occur in the network. The PMIPMR algorithm reduces blocking rate significantly and increases
the wavelength utilization by avoiding congestion in future multicast session requests. We measured the performance of the
proposed algorithm in terms of blocking rate and the resource utilization. The simulation results demonstrate that the PMIPMR
algorithm is superior to the previous multicast routing algorithms using the Capability-based-Connection algorithm based on
Capability-based-Priority and Spawn-from-VS methods. 相似文献
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We consider large optical networks in which nodes employ wavelength-routing switches which enable the establishment of wavelength-division-multiplexed (WDM) channels, called lightpaths, between node pairs. We propose a practical approach to solve routing and wavelength assignment (RWA) of lightpaths in such networks. A large RWA problem is partitioned into several smaller subproblems, each of which may be solved independently and efficiently using well-known approximation techniques. A multicommodity flow formulation combined with randomized rounding is employed to calculate the routes for lightpaths. Wavelength assignments for lightpaths are performed based on graph-coloring techniques. Representative numerical examples indicate the accuracy of our algorithms 相似文献
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Xiaowen Chu Bo Li 《Networking, IEEE/ACM Transactions on》2005,13(3):704-715
Blocking probability has been one of the key performance indexes in the design of wavelength-routed all-optical WDM networks. Existing research has demonstrated that an effective Routing and Wavelength Assignment (RWA) algorithm and wavelength conversion are two primary vehicles for improving the blocking performance. However, these two issues have largely been investigated separately; in particular the existing RWA algorithms have seldom considered the presence of wavelength conversion. In this paper, we firstly demonstrate that the existing dynamic RWA algorithms do not work well in the presence of wavelength conversion as they usually only take into account the current traffic, and do not explicitly consider the route lengths. We then propose a weighted least-congestion routing and first-fit wavelength assignment (WLCR-FF) algorithm that considers both the current traffic load and the route lengths jointly. We further introduce an analytical model that can evaluate the blocking performance for WLCR algorithm. We carry out extensive numerical studies over typical topologies including ring, mesh-torus, and the 14-node NSFNET; and compare the performance of WLCR-FF with a wide variety of existing routing algorithms including static routing, fixed-alternate routing and least-loaded routing. The results conclusively demonstrate that the proposed WLCR-FF algorithm can achieve much better blocking performance in the presence of sparse or/and full wavelength conversion. 相似文献
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《Networking, IEEE/ACM Transactions on》2008,16(4):970-983
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There are two strategies for solving Routing and Wavelength Assignment (RWA) in wavelength-routed networks: centralized and distributed. Centralized approaches are appropriate for small networks with light traffic, whereas distributed approaches are suitable for large networks with heavy traffic. Solving RWA problem in distributed algorithms can be generally divided into two phases: routing phase and wavelength assignment phase. Allocating a wavelength over a physical path for a connection request can be performed by one of two major strategies: Backward Reservation Method (BRM) and Forward Reservation Method (FRM). In this work, we assume that every node in the network can be equipped with a number of wavelength converters. Wavelength converters are usually chosen in a free policy. However, we propose a distributed algorithm, called Minimum-Conversion Backward Reservation Method (MC-BRM), that attempts to establish light-paths with minimum number of wavelength conversions. The MC-BRM algorithm can efficiently reduce the number of required wavelength conversions in the network. Besides improving blocking probability, MC-BRM can lead to better fairness in establishing light-paths with different number of hops. Finally, we make the worst case analysis for estimating wavelength conversion usages in individual nodes. 相似文献
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Wavelength Conversion Placement in WDM Mesh Optical Networks* 总被引:1,自引:0,他引:1
Wavelength conversion helps improve the performance of wavelength division multiplexed (WDM) optical networks that employ wavelength routing. In this paper, we address the problem of optimally placing a limited number of wavelength converters in mesh topologies. Two objective functions, namely, minimizing the average blocking probability and minimizing the maximum blocking probability over all routes, are considered. In the first part of the paper, we extend an earlier analytical model to compute the blocking probability on an arbitrary route in a mesh topology, given the traffic and locations of converters. We then propose heuristic algorithms to place wavelength converters, and evaluate the performance of the proposed heuristics using the analytical model. Results suggest that simple heuristics are sufficient to give near-optimal performance. 相似文献
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Light-trail is an efficient and feasible technology for IP transport over all-optical networks. The proposition of light-trails
for all-optical networks has demonstrated a number of advantages over other paradigms such as Wavelength Routing (WR), Optical
Burst Switching (OBS) and Optical Packet Switching (OPS). This article tackles the routing problem of light-trails with the
solution objective of minimizing the number of needed light-trails to accommodate an offered traffic matrix. We present two
enhancements to the Integer Linear Programming (ILP) formulation of the routing problem. We also propose a computationally
efficient routing heuristic for use with static and incremental traffic models. The heuristic is based on routing flows one-by-one.
This is done by assigning a set of attributes to each flow and to each network path. The flow attributes are used to determine
the order in which flows are presented to the routing algorithm. The path attributes are used to determine which path is selected
to route the flow at hand. The efficiency of the proposed heuristic is confirmed using example problems of different network
topologies. 相似文献