In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some oth...In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some other terms are presented. Based on this model and relevant Routing and Wavelength Assign- ment (RWA) strategy, a unicast RWA algorithm and a multicast RWA algorithm are presented. The wave- length-dependent equivalent arc expresses the schedule of local RWA and the equivalent network expresses the whole topology of WDM optical networks, so the two algorithms are of the flexibility in RWA and the optimi- zation of the whole problem. The theoretic analysis and simulation results show the two algorithms are of the stronger capability and the lower complexity than the other existing algorithms for RWA problem, and the complexity of the two algorithms are only related to the scale of the equivalent networks. Finally, we prove the two algorithms’ feasibility and the one-by-one corresponding relation between the equivalent multicast tree and original multicast tree, and point out the superiorities and drawbacks of the two algorithms respectively.展开更多
Given a set of lightpath connection requests in an all-10 Gb/s optical dense wavelength division multiplexed (DWDM) Ethernet network, lightpaths are designed. In addition the wavelength channels are assigned subject t...Given a set of lightpath connection requests in an all-10 Gb/s optical dense wavelength division multiplexed (DWDM) Ethernet network, lightpaths are designed. In addition the wavelength channels are assigned subject to minimization of the channel blocking and provisional requests satisfying the limits due to accumulative linear dispersion effects over the hops. This paper proposes a routing and wavelength assignment scheme for DWDM long-haul optical networks that includes routing, assignment and reservation of different wavelength channels operating under the Generalized Multiprotocol Label Switching (GMPLS) environment. The GMPLS framework can offer an approach to implement IP over DWDM with variable weighting assignments of routes based on the limitations due to residual dispersion accumulated on the lightwave path. The modeling is implemented under the framework of an object-oriented modeling platform OMNeT++. Network performance tests are evaluated based mainly on a long-haul terrestrial fiber mesh network composed of as well as three topologies structured as chain, ring, and mesh configurations. Blocking probability of lightpath connection requests are examined with the average link utilization in the network employing variable number of wavelength channels in association with the limits of route distance due to linear chromatic and polarization mode dispersion effects.展开更多
After analyzing the merits and shortcomings of Fixed-Alternated Routing algorithm (FAR) and Least Loaded Routing algorithm (LLR),we propose one novel dynamic optical routing algorithm. Having considered the influences...After analyzing the merits and shortcomings of Fixed-Alternated Routing algorithm (FAR) and Least Loaded Routing algorithm (LLR),we propose one novel dynamic optical routing algorithm. Having considered the influences of path’s length and path’s congestion just like in FAR and LLR,we take into account the network resource status-amount of free wavelengths in the network. Proposed algorithm sets up connections on three possible paths according to amount of available free wave-lengths in the network,which effectively decreases the blocking probability. The National Science Foundation (NSF) network and mesh-torus network simulation results show that the performance of this algorithm is better than that of FAR and LLR.展开更多
Conventional optical burst switching(OBS)technique adopts purely statistical multiplex mechanismso that the bursts collide with each other very easily.To address this problem,a novel proactive con-tention avoidance sc...Conventional optical burst switching(OBS)technique adopts purely statistical multiplex mechanismso that the bursts collide with each other very easily.To address this problem,a novel proactive con-tention avoidance scheme is proposed,which assigns dedicated wavelengths to each ingress node,then st-numbering algorithm is used to construct the traffic load balanced spanning trees .In this way,contentioncan be eliminated at ingress nodes,and the amount of bursts that could be accommodated by ingressnodes will be maximized.Further,those unused wavelengths left by traffic load balanced spanning treeare also organized as partial trees to carry bursts,thus the link utilization can be improved effectively.Simulation result shows that our scheme can improve the burst loss performance significantly without thewavelength converters or optical buffers comparing to other popular routing and wavelength assignment(RWA)algorithms.展开更多
A new routing and wavelength assignment method applied in hierarchical wavelength division multiplexing(WDM)networks is proposed.The algorithm is called offline band priority algorithm(offline BPA).The offline BPA tar...A new routing and wavelength assignment method applied in hierarchical wavelength division multiplexing(WDM)networks is proposed.The algorithm is called offline band priority algorithm(offline BPA).The offline BPA targets to maximize the number of waveband paths under the condition of minimum number of wavelengths,and solve the routing and wavelength assignment(RWA)problem with waveband grooming to reduce cost.Based on the circle construction algorithm,waveband priority function is introduced to calculate the RWA problem.Simulation results demonstrate that the proposed algorithm achieves significant cost reduction in WDM network construction.展开更多
在全光网中,信号传输损伤会恶化动态光路连接的阻塞率性能,有必要在研究动态路由与波长分配RWA(routing and wavelength assignment)算法时考虑信号传输损伤的影响。介绍和阐述了全光网中的信号传输损伤及其对动态RWA算法性能的影响;结...在全光网中,信号传输损伤会恶化动态光路连接的阻塞率性能,有必要在研究动态路由与波长分配RWA(routing and wavelength assignment)算法时考虑信号传输损伤的影响。介绍和阐述了全光网中的信号传输损伤及其对动态RWA算法性能的影响;结合已有的信号传输损伤模型提出了一种基于信号损伤限制的动态RWA算法,并对其性能进行了计算机仿真分析。仿真结果表明:该算法能有效地减小信号传输损伤对光网动态连接的阻塞率性能的影响,同时还具有较快的运算速度。展开更多
基于共享风险链路组SRLG(shared risk link group)的通路保护策略是光网络中的一种重要的生存性机制,而合理的通路保护路由与波长分配RWA(routing and wavelength assignment)算法是实现该生存性机制的一个关键。研究了基于SRLG通路保...基于共享风险链路组SRLG(shared risk link group)的通路保护策略是光网络中的一种重要的生存性机制,而合理的通路保护路由与波长分配RWA(routing and wavelength assignment)算法是实现该生存性机制的一个关键。研究了基于SRLG通路保护的动态RWA算法,包括专用通路保护和共享通路保护算法;使用了不同的选路和波长分配算法分别实现了基于这两种通路保护策略的RWA算法,并对其性能进行了计算机仿真,研究了不同路由和波长分配算法对通路保护算法性能的影响。从仿真结果可以看出:通过使用更好的选路和波长分配算法可以进一步提高基于SRLG通路保护的动态RWA算法的性能。展开更多
基金Supported by the Natrual Science Foundation of Shaanxi (No.2004A02) and Outstanding Scholar Project of P. R. China (2002).
文摘In this paper, a Wavelength Division Multiplexing (WDM) network model based on the equivalent networks is described, and wavelength-dependent equivalent arc, equivalent networks, equivalent multicast tree and some other terms are presented. Based on this model and relevant Routing and Wavelength Assign- ment (RWA) strategy, a unicast RWA algorithm and a multicast RWA algorithm are presented. The wave- length-dependent equivalent arc expresses the schedule of local RWA and the equivalent network expresses the whole topology of WDM optical networks, so the two algorithms are of the flexibility in RWA and the optimi- zation of the whole problem. The theoretic analysis and simulation results show the two algorithms are of the stronger capability and the lower complexity than the other existing algorithms for RWA problem, and the complexity of the two algorithms are only related to the scale of the equivalent networks. Finally, we prove the two algorithms’ feasibility and the one-by-one corresponding relation between the equivalent multicast tree and original multicast tree, and point out the superiorities and drawbacks of the two algorithms respectively.
文摘Given a set of lightpath connection requests in an all-10 Gb/s optical dense wavelength division multiplexed (DWDM) Ethernet network, lightpaths are designed. In addition the wavelength channels are assigned subject to minimization of the channel blocking and provisional requests satisfying the limits due to accumulative linear dispersion effects over the hops. This paper proposes a routing and wavelength assignment scheme for DWDM long-haul optical networks that includes routing, assignment and reservation of different wavelength channels operating under the Generalized Multiprotocol Label Switching (GMPLS) environment. The GMPLS framework can offer an approach to implement IP over DWDM with variable weighting assignments of routes based on the limitations due to residual dispersion accumulated on the lightwave path. The modeling is implemented under the framework of an object-oriented modeling platform OMNeT++. Network performance tests are evaluated based mainly on a long-haul terrestrial fiber mesh network composed of as well as three topologies structured as chain, ring, and mesh configurations. Blocking probability of lightpath connection requests are examined with the average link utilization in the network employing variable number of wavelength channels in association with the limits of route distance due to linear chromatic and polarization mode dispersion effects.
文摘After analyzing the merits and shortcomings of Fixed-Alternated Routing algorithm (FAR) and Least Loaded Routing algorithm (LLR),we propose one novel dynamic optical routing algorithm. Having considered the influences of path’s length and path’s congestion just like in FAR and LLR,we take into account the network resource status-amount of free wavelengths in the network. Proposed algorithm sets up connections on three possible paths according to amount of available free wave-lengths in the network,which effectively decreases the blocking probability. The National Science Foundation (NSF) network and mesh-torus network simulation results show that the performance of this algorithm is better than that of FAR and LLR.
基金supported by the National Natural Science Foundation of China(No.60572050)the National High Technology Research and Development Programme of China(No.2008AA01Z211)
文摘Conventional optical burst switching(OBS)technique adopts purely statistical multiplex mechanismso that the bursts collide with each other very easily.To address this problem,a novel proactive con-tention avoidance scheme is proposed,which assigns dedicated wavelengths to each ingress node,then st-numbering algorithm is used to construct the traffic load balanced spanning trees .In this way,contentioncan be eliminated at ingress nodes,and the amount of bursts that could be accommodated by ingressnodes will be maximized.Further,those unused wavelengths left by traffic load balanced spanning treeare also organized as partial trees to carry bursts,thus the link utilization can be improved effectively.Simulation result shows that our scheme can improve the burst loss performance significantly without thewavelength converters or optical buffers comparing to other popular routing and wavelength assignment(RWA)algorithms.
文摘A new routing and wavelength assignment method applied in hierarchical wavelength division multiplexing(WDM)networks is proposed.The algorithm is called offline band priority algorithm(offline BPA).The offline BPA targets to maximize the number of waveband paths under the condition of minimum number of wavelengths,and solve the routing and wavelength assignment(RWA)problem with waveband grooming to reduce cost.Based on the circle construction algorithm,waveband priority function is introduced to calculate the RWA problem.Simulation results demonstrate that the proposed algorithm achieves significant cost reduction in WDM network construction.
文摘在全光网中,信号传输损伤会恶化动态光路连接的阻塞率性能,有必要在研究动态路由与波长分配RWA(routing and wavelength assignment)算法时考虑信号传输损伤的影响。介绍和阐述了全光网中的信号传输损伤及其对动态RWA算法性能的影响;结合已有的信号传输损伤模型提出了一种基于信号损伤限制的动态RWA算法,并对其性能进行了计算机仿真分析。仿真结果表明:该算法能有效地减小信号传输损伤对光网动态连接的阻塞率性能的影响,同时还具有较快的运算速度。
文摘基于共享风险链路组SRLG(shared risk link group)的通路保护策略是光网络中的一种重要的生存性机制,而合理的通路保护路由与波长分配RWA(routing and wavelength assignment)算法是实现该生存性机制的一个关键。研究了基于SRLG通路保护的动态RWA算法,包括专用通路保护和共享通路保护算法;使用了不同的选路和波长分配算法分别实现了基于这两种通路保护策略的RWA算法,并对其性能进行了计算机仿真,研究了不同路由和波长分配算法对通路保护算法性能的影响。从仿真结果可以看出:通过使用更好的选路和波长分配算法可以进一步提高基于SRLG通路保护的动态RWA算法的性能。
