Hybrid Policy of Routing and Spectrum Assignment in Elastic Optical Networks

The major challenge in elastic optical networks is to determine the path of a connection and to allocate spectral resources on the links of this path. This problem consists of two sub-problems, routing and spectrum allocation. In the literature, these sub-problems are solved with a predefined order for all topology node pairs. Recent work proposes hybrid resolution algorithms based on connection demand and network state to provide a solution to these problems. However, the blocking rate of new connection requests has become problematic. In this work, we propose a hybrid routing and spectrum assignment policy to improve blocking rate of new connection requests. The proposed solution consists to change the routing policy of a pair node if the connection request is blocked. This algorithm improves the blocking rate of new connection requests.

Anycast Transmission in Routing Modulation Level Spectrum Assignment (RMLSA) Problem on Space Division Multiplexing (SDM) Elastic Optical Networks (EON)

With the rise of cloud computing in recent years, a large number of streaming media has yielded an exponential growth in network traffic. With the now present 5G and future 6G, the development of the Internet of Things (IoT), social networks, video on demand, and mobile multimedia platforms, the backbone network is bound to bear more traffic. The transmission capacity of Single Core Fiber (SCFs) may be limited in the future and Spatial Division Multiplexing (SDM) leveraging multi-core fibers promises to be one of the solutions for the future. Currently, Elastic optical networks (EONs) with multi-core fibers (MCFs) are a kind of SDM-enabled EONs (SDM-EON) used to enhance the capacity of transmission. The resource assignment in MCFs, however, will be subject to Inter-Core Crosstalk (IC-XT), hence, reducing the effectiveness of transmission. This research highlights the routing, modulation level, and spectrum assignment (RMLSA) problems with anycast traffic mode in SDM-EON. A multipath routing scheme is used to reduce the blocking rate of anycast traffic in SDM-EON with the limit of inter-core crosstalk. Hence, an integer linear programming (ILP) problem is formulated and a heuristic algorithm is proposed. Two core-assignment strategies: First-Fit (FF) and Random-Fit (RF) are used and their performance is evaluated through simulations. The simulation results show that the multipath routing method is better than the single-path routing method in terms of blocking ratio and spectrum utilization ratio. Moreover, the FF is better than the RF in low traffic load in terms of blocking ratio (BR), and the opposite in high traffic load. The FF is better than the RF in terms of a spectrum utilization ratio. In an anycast protection problem, the proposed algorithm has a lower BR than previous works.

Multi-Core Virtual Concatenation Scheme Considering Inter-Core Crosstalk in Spatial Division Multiplexing Enabled Elastic Optical Networks

Spatial division multiplexing enabled elastic optical networks(SDM-EONs) are the potential implementation form of future optical transport networks, because it can curve the physical limitation of achievable transmission capacity in single-mode fiber and single-core fiber. However, spectrum fragmentation issue becomes more serious in SDM-EONs compared with simple elastic optical networks(EONs) with single mode fiber or single core fiber. In this paper, multicore virtual concatenation(MCVC) scheme is first proposed considering inter-core crosstalk to solve the spectrum fragmentation issue in SDM-EONs. Simulation results show that the proposed MCVC scheme can achieve better performance compared with the baseline scheme, i.e., single-core virtual concatenation(SCVC) scheme, in terms of blocking probability and spectrum utilization.

Resource Allocation Using SPA Based on Different Cost Functions in Elastic Optical Networks

Routing, modulation and spectrum allocation in elastic optical networks is a problem aiming at increasing the capacity of the network. Many algorithms such as shortest path algorithm can be used as the routing section of this problem. The efficiency of these algorithms is partly based on how the cost of each link is defined. In this study, we considered several basic metrics in cost of network links and compared their effects on the network capacity. In particular, the static costs and the dynamic costs were evaluated and compared. For dynamic scenarios, compared to static scenarios, at least one additional factor, the usage of the links, was added. We further considered a new factor that is based on probability of accommodating the signal at a given time in any given link. The results show that, among them, the shortest path algorithm provides the least blocking probability when the cost is a combination of link length and the abovementioned possibility/usage of the link.

Elastic Resource Allocation for Multi-Granularity Multicasting Traffic in OFDM-Based Optical Networks

With the increasing requirements of the multicast services in the whole data traffic service, the optical multicast technology becomes a key technology supporting wide bandwidth and high speed multicasting communication. The transmission efficiency, capacity and robustness of optical multicast network can be further improved by introducing network coding technology into optical multicast networks. Meanwhile, facing to demand of emerging rate-variable multi-granularity multicast service, a multi-path transmission scheme based on network coding for routing and spectrum allocation (RSA) is proposed. It can not only allocate spectrum resources effectively and flexibly for various-rate multicast traffic, but also balance the network load, improve network throughput and reduce transmission blocking rate. In this paper, RSA problem is decomposed into two subproblems, namely routing allocation based on network coding and spectrum allocation based on maximum spectrum first (MSF) strategy, which are solved sequentially. Simulation experiments are carried out to analyze transmission performance with proposed RSA scheme. The simulation results show that the proposed RSA mechanism can allocate spectrum resources efficiently and flexibly for multi-granularity multicast traffic. Compared with RSA schemes based on shortest path tree (SPT) and minimal spanning tree (MST), the proposed RSA scheme is more efficient for spectrum resource utilization and load balancing, and spectrum resource is saved more than 20%.

Cost-Minimized Virtual Elastic Optical Network Provisioning with Guaranteed QoS

Network virtualization is important for elastic optical networks(EONs)because of more flexible service provisioning.To ensure guaranteed quality of service(QoS)for each virtual elastic optical network(VEON),clients usually request network resources from a network operator based on their bandwidth requirements predicted from historical traffic demands.However,this may not be efficient as the actual traffic demands of users always fluctuate.To tackle this,we propose a new VEON service provisioning scheme,called SATP,which consists of three stages,i.e.,spectrum assignment(SA),spectrum trading(ST),and spectrum purchasing(SP).Unlike conventional once-for-all VEON service provisioning approaches,the SATP scheme first allocates spectrum resources to VEONs according to their predicted bandwidth requirements with a satisfaction ratio α(0<α≤1).Then,to minimize service degradation on VEONs which are short of assigned spectra for their peak traffic periods,the scheme allows VEONs to trade spectra with each other according to their actual bandwidth requirements.Finally,it allows VEON clients to purchase extra spectrum resources from a network operator if the spectrum resources are still insufficient.To optimize this entire process,we formulate the problem as a mixed integer linear programming(MILP)model and also develop efficient heuristic algorithms for each stage to handle large test scenarios.Simulations are conducted under different test conditions for both static and dynamic traffic demand scenarios.Results show that the proposed SATP scheme is efficient and can achieve significant performance improvement under both static and dynamic scenarios.

Minimizing Traffic Blocking and Inter-Crosstalk in Spatial Division Multiplexing over Elastic Optical Networking

As a promising solution, virtualization is vigorously developed to eliminate the ossification of traditional Internet infrastructure and enhance the flexibility in sharing the substrate network (SN) resources including computing, storage, bandwidth, etc. With network virtualization, cloud service providers can utilize the shared substrate resources to provision virtual networks (VNs) and facilitate a wide and diverse range of applications. As more and more internet applications migrate to the cloud, the resource efficiency and the survivability of VNs, such as single link failure or large-scale disaster survivability, have become crucial issues. Elastic optical networks have emerged in recent years as a strategy for dealing with the divergence of network application bandwidth needs. The network capacity has been constrained due to the usage of only two multiplexing dimensions. As transmission rates rise, so does the demand for network failure protection. Due to their end-to-end solutions, those safe-guarding paths are of particular importance among the protection methods. Due to their end-to-end solutions, those safeguarding paths are of particular importance among the protection methods. This paper presents approaches that provide a failure-independent route-protecting p-cycle for path protection in space-division multiplexed elastic optical networks. This letter looks at two SDM network challenges and presents a heuristic technique (k-shortest path) for each. In the first approach, we study a virtual network embedding (SVNE) problem and propose an algorithm for EONs, which can combat against single-link failures. We evaluate the proposed POPETA algorithm and compare its performance with some counterpart algorithms. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance in terms of spectrum utilization and blocking ratio, even if with a higher backup redundancy ratio.

SDM-EON中基于串扰避免的多纤芯分配算法

为了解决空分复用弹性光网络中的频谱碎片、路由频谱纤芯分配(RSCA)和低业务负载下芯间串扰等问题,建立针对多纤芯RSCA问题的动态业务分割整数线性规划(ILP)模型,提出基于串扰避免的多纤芯分配算法(PS-MCT)。在路由选择阶段,综合路径负载和跳数设计路径排序公式;在频谱分配阶段,将纤芯分组,组内纤芯分类和多纤芯分配相结合;通过业务分割的方式使多个子业务独立地在同组内的多条纤芯上传输,从而减小串扰和碎片的产生。仿真结果表明,与对比算法相比,所提算法在带宽阻塞率和频谱利用率方面都取得了较好的性能。

Crosstalk-aware RCSA for spatial division multiplexing enabled elastic optical networks with multi-core fibers

In this Letter,we propose two crosstalk-aware routing,core,and spectrum assignment(CA-RCSA)algorithms for spatial division multiplexing enabled elastic optical networks(SDM-EONs)with multi-core fibers.First,the RCSA problem is modeled,and then a metric,i.e.,CA spectrum compactness(CASC),is designed to measure the spectrum status in SDM-EONs.Based on CASC,we propose two CA-RCSA algorithms,the first-fit(FF)CASC algorithm and the random-fit(RF)CASC algorithm.Simulation results show that our proposed algorithms can achieve better performance than the baseline algorithm in terms of blocking probability and spectrum utilization,with FF-CASC providing the best performance.

Reinforced virtual optical network embedding algorithm in EONs for edge computing

As the core technology of optical networks virtualization, virtual optical network embedding(VONE) enables multiple virtual network requests to share substrate elastic optical network(EON) resources simultaneously and hence has been applicated in edge computing scenarios. In this paper, we propose a reinforced virtual optical network embedding(R-VONE) algorithm based on deep reinforcement learning(DRL) to optimize network embedding policies automatically. The network resource attributes are extracted as the environment state for model training, based on which DRL agent can deduce the node embedding probability. Experimental results indicate that R-VONE presents a significant advantage with lower blocking probability and higher resource utilization.

基于孤立森林算法的弹性光网络异常流量自动识别方法

弹性光网络流量传输受到时间波动导致异常,为了提高网络传输稳定性,提出基于孤立森林算法的弹性光网络异常流量自动识别算法。根据流量的异常分布特征和正常数据的差异性进行波谱密度检测,构建弹性光网络流量的谱特征提取模型,通过低通滤波器卷积向量重组,实现对异常流量的谱特征筛选,采用孤立森林算法实现对网络流量异常检测的自适应寻优控制,结合多维空间结构重组方法实现对弹性光网络异常流量检测和识别。结果表明,漏检率及误检率较低,分别为3.16%,1.03%。检测用时较少,仅用16秒。在进行检测时,外部入侵率未超过1%,抗扰性较强。

基于深度学习的面向IP-over-EON的可编程跨层网络业务性能感知系统

为了实现实时的、细粒度的网络性能监测与调整,并且满足不同应用的特定服务质量需求,提出了基于深度学习的面向IP-over-EON的可编程跨层网络业务性能感知系统。该系统将基于网络业务性能感知的分布式网络监测与集中式网络管控相结合,分布式网络监测实现跨层和细粒度的网络监控,并基于深度学习进行数据分析。实验结果表明,该系统通过有机地结合集中式与分布式的处理方式,实现了及时的、自动化的网络控制与管理,具有良好的可扩展性。

EON中针对提前预留业务的碎片感知RSA算法

为了减少弹性光网络(EON)中的频谱和时间碎片,针对提前预留(AR)业务提出一种碎片感知路由与频谱分配(RSA)算法。在选路阶段,该算法采用K最短路径算法,综合考虑路径距离、跳数、频谱资源消耗和邻接链路数等因素影响来挑选侯选路径集;在资源分配阶段,则采用局部影响因子统计可能产生的频谱和时间碎片,以降低候选资源块周围的频谱、时间资源碎片化程度,并利用整体影响因子尽可能将占用资源集中在频率轴边界处,以增加中间空闲资源连续性,同时还引入时域资源使用度因子以避免过度占用资源。仿真结果表明,该算法进一步改善了带宽阻塞率性能,提高了资源利用率。

一种基于串扰污染区域的SDM-EON网络中超级通道构建

空分复用弹性光网络(Space Division Multiplexing Elastic Optical Networks,SDM-EON)技术具有细粒度、高容量、高速率等特性,是未来光传输网络的核心技术,然而,加入了空间维度,网络中超通道的构建更加复杂化。为了有效地构建SDM-EON中超通道,文章首先提出核间串扰污染区域(Crosstalk-contaminated Area,CA)的新概念,描述受到核间串扰的频谱段。基于CA的概念,提出了一种新型的构建超级通道的路由、频谱和核分配(RSCA)算法。仿真结果表明,基于CA的超级通道构建方案(SCCA)比基准算法有更低的阻塞率,能实现更好的性能。

弹性光网络中基于频谱窗滑动的时变业务共享保护方法

针对弹性光网络(EONs)中时变业务生存性传输时消耗频谱资源多和业务阻塞率高的问题,该文提出一种基于频谱窗滑动的时变业务共享保护(TTSP-SWS)算法。TTSP-SWS算法选择可用频谱块承载权重和保护频谱块共享度的共享保护路径代价函数值最小的保护路径;通过在保护路径上滑动频谱窗,将时变业务分配至频谱窗共享度最高的频隙位置;当时变业务带宽变化时,采用基于频谱窗滑动的生存性扩展或压缩频谱分配策略调整时变业务的带宽分配。仿真结果表明,该文所提TTSP-SWS算法能降低网络的业务阻塞率和保护资源冗余度。

光路邻居链路频谱碎片感知的虚拟光网络协同映射算法

为了解决虚拟网络映射光路太长和频谱碎片化的问题,论文提出一种基于邻居链路碎片感知的虚拟网络映射算法(Virtual Optical Network Embedding based on Adjacency Link Fragmentation Awareness, ALFA-VONE).设计考虑虚拟节点资源需求和邻居节点映射状态的权值计算方法,提高虚拟节点映射的成功率;使用相邻虚拟节点-虚拟链路协同映射方法,缩短映射光路长度和减少所需频隙数目;设计光路可用资源评估方法,以提高虚拟链路映射成功率;考虑拟分配频谱块对光路以及邻居链路造成的频谱碎片影响,设计频谱碎片影响值评估法,以提高频谱资源利用率.仿真结果表明:当网络负载为130 Erlang时,所设计算法的平均映射光路跳数减少28.4%,带宽利用率提高4.56%.

基于频谱切片的弹性光网络中可调度请求资源分配算法

针对确定业务开始时间和结束时间特性的可调度请求加重了弹性光网络的资源碎片率和带宽阻塞率的问题,设计了一种配置频谱切片机的弹性光网络节点结构,并提出一种基于频谱切片的可调度请求路由频谱和时间分配(SS-RSTA)算法。在路由选择阶段,设计了一种综合考虑路径长度、路径碎片率和节点可用频谱切片机数量的路径权重值的路由选择策略,为可调度请求选择路径权重值最大的路由;在资源分配阶段,采用链路的资源碎片感知方法为可调度请求选择可用的频谱和时间资源窗口;当资源分配失败时,采用频谱切片准则将可调度请求切分为多个子带宽请求,以增加可调度请求频谱分配成功的概率,提高频谱-时间碎片的利用率。仿真结果表明,所提算法可改善网络的带宽阻塞率和提高网络的频谱利用率。

基于群智能优化技术的光网络资源动态分配研究

数据量以及光网络用户增多为光网络带来负担,导致广域骨干网拥堵,为此,提出基于群智能优化技术的光网络资源动态分配方法。描述光网络资源,计算平行链路的利用率,优化平行链路利用率,分配弹性光网络资源,构建光网络吞吐量最大化和光网络节点时延最小化的目标函数,通过粒子群算法,求解队列动态更新函数,获取最优解,为弹性光网络资源动态分配结果。实验结果表明,所提方法的资源动态分配速率式中在80%以上,带宽阻塞率最高仅为13.8%,光网络节点时延短。降低光网络拥堵程度,保证光网络资源利用的充分性。

一种提高弹性光网络性能的PDT-TFDBT策略

为了提高弹性光网络的性能,提出一种时频域及阻塞门限联合触发的周期碎片整理(PDT-TFDBT)策略,该策略在触发条件方面采用改进碎片化指数的阻塞延迟触发机制,减少未阻塞时进行无效整理的负载量;在整理顺序方面综合考虑业务的时域和频域特征,合理分配业务的重构顺序,同时引入启发式深度学习辅助的路由及频谱分配(DKA-RSA)算法。仿真结果表明,PDT-TFDBT策略不仅可以减少重构业务数量和频谱碎片,而且进一步降低了业务阻塞率,提高了频谱利用率。