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1.
The issue of wavelength assignment is one of the most important factors that affect the capacity for the deployment of optical
networks. This issue becomes more critical for multicast connections, especially when the network nodes have no wavelength
conversion capability. Although the wavelength assignment can be more flexible if each node can perform wavelength conversion,
the deployment cost increases accordingly. A compromise is to support a limited portion of conversion nodes in the WDM network.
We propose a systematic approach for the wavelength assignment of multicast connections in WDM networks with sparse wavelength
conversion nodes. The efficiency of the arrangement of wavelength is measured by its influences on the available capacity
of the network and the consumption of wavelengths. By using the proposed approach, the Static Cost Greedy (SCG) algorithm
[8] can be easily extended to be applicable in a Sparse Wavelength Conversion Network (SWCN). In addition, instead of SCG,
the Minimum-Effect-First (MEF) algorithm is proposed to maximize the network capacity during wavelength assignment. We compare
the performance of the proposed MEF methods with the extended SCG scheme through exhaustive simulations. The experimental
results indicate that the proposed MEF schemes demonstrate much better performance than the SCG scheme. We also found that
the performance is not always improved proportionally to the increment of the wavelength conversion nodes. The improvement
reaches saturation when the number of conversion nodes is above 35% of the total number of nodes.
相似文献
I-Hsuan PengEmail: |
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This paper addresses the problem of multicast wavelength assignment for sparse wavelength conversion (MWA-SWC) in wavelength-routed wavelength-division-multiplexing (WDM) networks. It aims to optimally allocate the available wavelength for each link of the multicast tree, given a sparse wavelength conversion network and a multicast request. To our knowledge, little research work has been done to address this problem in literature.In this paper, we propose a new technique called MWA-SWC algorithm to solve the problem. The algorithm first maps the multicast tree from the sparse conversion case to the full conversion case by making use of a novel virtual link method to carry out the tree mapping. The method provides a forward mapping to generate an auxiliary tree as well as a reverse mapping to recover the original tree. Applying the auxiliary tree, we propose a dynamic programing algorithm for the wavelength assignment (WA) aiming to minimize the number of wavelength converters (NWC) required. Simulation results show that our new algorithm outperforms both random and greedy algorithms with regard to minimizing the NWC. Testing on various scenarios by varying the number of wavelength conversion nodes in the tree has confirmed the consistency of the performance. The primary use of the MWA-SWC algorithm is for static traffic. However, it can also serve as a baseline for dynamic heuristic algorithms. Typically, the MWA-SWC algorithm will provide great benefit when the number of available wavelengths on each link of the multicast tree is relatively large and the performance advantage is significant. 相似文献
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We have developed a new layered-routing approach to address the problem of all-optical multicast over wavelength-routed wavelength
division multiplexing (WDM) networks. We model the WDM network as a collection of wavelength layers with sparse light- splitting
(LS) and wavelength conversion (WC) capabilities. We apply the degree constraint technique to solve the problem. The approach
is capable of completing multicast routing and wavelength assignment (MCRWA) in one step. We propose two generic frameworks
to facilitate heuristic development. Any heuristic that is derived from either Prim’s or Kruskal’s algorithm can be easily
imported to solve the MCRWA problem. One example is given for each framework to demonstrate heuristic development. Extensive
simulations were carried out to measure the performance of heuristics developed from the frameworks. The results show that
the STRIGENT scheme is suitable for hardware design and it is advisable to deploy light splitters and wavelength converters
to the same node for better performance. 相似文献
6.
Most existing algorithms for the problem of optical signal splitter placement or multicast splitting-capable node placement
in a WDM network are based on the performance of attempting a large set of randomly generated multicast sessions in the network.
Experiments show that placement of multicast capable nodes based on their importance for routing one set of multicast sessions
may not be a right choice for another set of multicast sessions. In this work, we propose placement algorithms that are based
on network topology and the relative importance of a node in routing multicast sessions, which is measured by our proposed
metrics. Since a network topology is fixed once given, the proposed algorithms are essentially network traffic independent.
We evaluate the proposed placement algorithms given static sets of multicast sessions as well as under dynamic traffic conditions,
which are routed using our splitter constrained multicast routing algorithm. Our results show that the proposed algorithms
perform better, compared to existing algorithms. 相似文献
7.
Dynamic wavelength assignment for multicast in all-optical WDM networks to maximize the network capacity 总被引:7,自引:0,他引:7
Jianping Wang Biao Chen Uma R.N. 《Selected Areas in Communications, IEEE Journal on》2003,21(8):1274-1284
We study the problem of wavelength assignment for multicast in order to maximize the network capacity in all-optical wavelength-division multiplexing networks. The motivation behind this work is to minimize the call blocking probability by maximizing the remaining network capacity after each wavelength assignment. While all previous studies on the same objective concentrate only on the unicast case, we study the problem for the multicast case. For a general multicast tree, we prove that the multicast wavelength assignment problem of maximizing the network capacity is NP-hard and propose two efficient greedy algorithms. We also study the same problem for a special network topology, a bidirectional ring network, which is practically the most important topology for optical networks. For bidirectional ring networks, a special multicast tree with at most two leaf nodes is constructed. Polynomial time algorithms for multicast wavelength assignment to maximize the network capacity exist under such a special multicast tree with regard to different splitting capabilities. Our work is the first effort to study the multicast wavelength assignment problem under the objective of maximizing network capacity. 相似文献
8.
该文首次研究了波分复用(Wavelength Division Multiplex,WDM)网络中如何在最佳节点中确定波长变换器数目的算法,设计了3种启发式算法,通过在NSFNET(the U.S.NationalScience Foundation backbone NETwork,美国科学基金会骨干网络),ARPANBT(the AdvancedResearch Projects Agency NETwork,美国高级研究规划局网络),CERNET(China Educationand Research NETwork,中国教育科研网络)上的仿真,比较了3种算法的性能差异,得出算法1的性能最优,且复杂度最低。另外,通过比较在部分节点以及全部节点中运用算法1确定波长变换器的数目,得出:在WDM网络中,在部分节点中装配有限的波长变换器也可以达到全部节点中装备波长变换器的性能,并且还可以降低光交叉连接设备(Optical Cross-Connects,OXC)的成本,减少复杂的控制。 相似文献
9.
In this paper, the sharing schemes of multicast in survivable Wavelength-Division Multiplexed (WDM) networks are studied and the concept of Shared Risk Link Group (SRLG) is considered. While the network resources are shared by the backup paths, the sharing way is possible to make the backup paths selfish. This selfishness leads the redundant hops of the backup route and a large number of primary lightpaths to share one backup link. The sharing schemes, especially, the self-sharing and cross-sharing, are investigated to avoid the selfishness when computing the backup light-tree. In order to decrease the selfishness of the backup paths, it is important to make the sharing links fair to be used. There is a trade-off between the self-sharing and cross-sharing, which is adjusted through simulation to adapt the sharing degree of each sharing scheme and save the network resources. 相似文献
10.
The advances in wavelength division multiplexing (WDM) technology are expected to facilitate bandwidth-intensive multicast
application by establishing a light-tree, which regards the source node as the root, and involves all the destination nodes.
The light-tree is sensitive to failures, e.g., a single fiber cut may disrupt the transmission of information to several destination
nodes. Thus, it is imperative to protect multicast sessions. In this work, we investigate the problem of protecting dynamic
multicast sessions in mesh WDM networks against single link failures. Our objectives are to minimize the usage of network
resources in terms of wavelength links for provisioning survivable multicast session, and to reduce the multicast session
blocking probability. We propose two efficient multicast session protecting algorithms, called Optimal Path Pair based Removing
Residual Links (OPP-RRL) and Source Leaf Path based Avoiding Residual Links (SLP-ARL), which try to reduce the usage of network
resource by removing or avoiding residual links in the topology consisting of light-tree and its backup paths. To evaluate
the proposed algorithms, we apply Integer Linear Programming (ILP) to generate an optimal solution. We also compare the proposed
algorithms with existing algorithms through simulation. Simulation results indicate that the two proposed algorithms have
better performance than other existing algorithms in terms of wavelength links required and network blocking probability.
Furthermore, the solutions generated by the two proposed algorithms are quite close to the solutions generated by ILP in terms
of the number of wavelength links required, when the network size is small. 相似文献
11.
With the rapid development of optical networking technology, it is now a realizable technique to support point-to-multipoint connections directly on the optical layer, giving rise to optical multicast. The topic of optical multicast has attracted much enthusiasm in recent years for the reason that it will not only make full use of the abundant bandwidth provided by optical fibers, but also take full advantage of multicast over the traditional point-to-point connection approach. In this paper, we present a comprehensive review of optical multicast over wavelength-routed WDM networks, covering the development of both data plane and control plane designs. In particular, we provide an up-to-date state-of-the-art review on the multicast routing and wavelength assignment problem. To the best of our knowledge, this is the most thorough and comprehensive review conducted so far on this topic in the literature. 相似文献
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Amin Ebrahimzadeh Akbar Ghaffarpour Rahbar Behrooz Alizadeh 《Optical Switching and Networking》2013,10(4):354-365
Routing and wavelength assignment (RWA) is the most concern in wavelength routed optical networks. This paper proposes a novel binary quadratic programming (BQP) formulation for the static RWA problem in order to balance traffic load among a network links more fairly. Subsequently, a greedy heuristic algorithm namely variable-weight routing and wavelength assignment (VW-RWA) is proposed to solve the developed BQP problem. In this method, the weight of a link is proportional to the link congestion. Performance evaluation results for different practical network topologies show that our proposed algorithm can decrease the number of required wavelengths in the network, blocking rate and variance of used wavelengths in each link. Besides, it is shown that the number of required wavelengths to establish call requests for a given network topology can be reduced at lower cost compared to other heuristics. 相似文献
15.
Shao Ziyu Yan Dongbin Li Zhengbin Wang Ziyu Xu Anshi 《Photonic Network Communications》2007,13(2):195-205
Wavelength routed optical networks have emerged as a technology that can effectively utilize the enormous bandwidth of the
optical fiber. Wavelength conversion technology and wavelength converters play an important role in enhancing fiber utilization
and in reducing the overall call blocking probability of the network. In this paper, we develop a new analytical model to
calculate the average blocking probability in multi-fiber link networks using limited-range wavelength conversion. Based on
the results obtained, we conclude that the proposed analytical model is simple and yet can effectively analyze the impact
of wavelength conversion ranges and number of fibers on network performance. Also a new heuristic approach for placement of
wavelength converters to reduce blocking probabilities is explored. Finally, we analyze network performance with the proposed
scheme. It can be observed from numerical simulations that limited-range converters placed at a few nodes can provide almost
the same blocking probability as full range wavelength converters placed at all the nodes. We also show that being equipped
with a multi-fiber per-link has the same effect as being equipped with the capability of limited-range wavelength conversion.
So a multi-fiber per-link network using limited-range wavelength conversion has similar blocking performance as a full wavelength
convertible network. Since a multi-fiber network using limited-range wavelength conversion could use fewer converters than
a single-fiber network using limited range wavelength conversion and because wavelength converters are today more expensive
than fiber equipment, a multi-fiber network in condition with limited-range wavelength conversion is less costly than a single-fiber
network using only limited-range wavelength conversion. Thus, multi-fiber per-link network using limited-range wavelength
conversion is currently a more practical method for all optical WDM networks. Simulation studies carried out on a 14-node
NSFNET, a 10-node CERNET (China Education and Research Network), and a 9-node regular mesh network validate the analysis. 相似文献
16.
This article proposes a new approach for routing and wavelength assignment (RWA) for permanent and reliable wavelength paths
(WP) in wide all-optical WDM networks with wavelength continuity constraint. Given a number of available wavelengths on each
optical fiber, for each simple link failure of the network, we seek to maximize the number of satisfied requests for connections.
This is known as RWAP problem. In our algorithm, called RWA with Minimum Loaded Link for Permanent and Reliable wavelength
paths (MLL-PR), routing is based on the search for the optimal path while trying to minimize the maximum load on the links of the network
in order to minimize the maximum link capacity and then minimize the number of dropped lightpaths after any link failure.
The wavelength assignment is based on a graph coloring method using tabu-search. A series of experiments using two well-known
networks (ARPANET and NSFNET) have been carried out in order to evaluate the performance of our approach, in terms of the
number of blocked demands, for different failure scenarios. Generally, our results are better than those provided by the current
solving approaches taken as reference.
相似文献
Zouhair GuennounEmail: |
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文章在一种已有的"子图+ADD(代数决策图)"的波长转换器配置算法的基础上,提出了用优先配置最大度节点的启发式思想对该算法进行改进,得到了新的"子图+BDF(大度节点优先分配)"算法.通过对两种算法进行计算机仿真,得到的模拟结果显示新算法在保持结果准确的同时,有效降低了运算的时间复杂度. 相似文献
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《Optical Fiber Technology》2014,20(4):341-352
This paper proposes an efficient overlay multicast provisioning (OMP) mechanism for dynamic multicast traffic grooming in overlay IP/MPLS over WDM networks. To facilitate request provisioning, OMP jointly utilizes a data learning (DL) scheme on the IP/MPLS layer for logical link cost estimation, and a lightpath fragmentation (LPF) based method on the WDM layer for improving resource sharing in grooming process. Extensive simulations are carried out to evaluate the performance of OMP mechanism under different traffic loads, with either limited or unlimited port resources. Simulation results demonstrate that OMP significantly outperforms the existing methods. To evaluate the respective influences of the DL scheme and the LPF method on OMP performance, provisioning mechanisms only utilizing either the IP/MPLS layer DL scheme or the WDM layer LPF method are also devised. Comparison results show that both DL and LPF methods help improve OMP blocking performance, and contribution from the DL scheme is more significant when the fixed routing and first-fit wavelength assignment (RWA) strategy is adopted on the WDM layer. Effects of a few other factors, including definition of connection cost to be reported by the WDM layer to the IP/MPLS layer and WDM-layer routing method, on OMP performance are also evaluated. 相似文献