智能光网络的多域生存性技术研究

自动交换光网络是传送网的发展趋势,而快速高效的生存性是其重要特点.介绍了光网络生存性,重点分析了多域网络和域间路由问题,并且提出了具体的实现多域网络的生存性方法.     

多域光网络中采用条件风险分离度的生存性策略

为了克服多域光网络中可扩展性约束的缺点,在多域光网络中提供区分业务的服务,提出一种采用条件风险分离度的多域光网络生存性策略.该策略给出条件风险分离度的概念,应用条件风险分离度实现域内虚链路映射,计算区分业务可靠性的端到端工作,保护路由对.仿真结果表明,所提生存性策略不仅能够区分业务可靠性,降低业务阻塞率,而且能够为业务提供平均高于其请求6.5%的可靠度.     

多域光网络生存性的关键技术研究

多域光网络的生存性作为衡量网络性能优劣的关键指标,与实际网络应用的关系最为密切,是当前迫切需要解决的关键问题;聚焦高速化、多业务化驱动的多域光网络环境下的生存性技术.基于光网络的多业务、分布式控制的特性,分析了多域光网络生存性机制的研究现状及面临的挑战;给出了一种针对多域光网络生存性问题的分类方法;结合多域光网络对生存性的需求,对相关关键技术进行了归类和研究,并指明了进一步研究的方向和重点.     

智能光网络多层生存性技术

分析了现有网络中独立的和层间协调的生存性机制,并且对基于GMPLS的智能光网络的多层生存性进行分析,可以看到智能光网络为多层网络生存性提供了更好的保证.     

多域全光网络快速多链路故障定位机制

提出了一种运用于多域全光网络的多链路故障定位机制.该机制根据网络中的告警信息确定多链路故障发生域;通过边界节点收集的监测信息和告警信息定位域间多链路故障;对于域内多链路故障,在分离各单故障后基于LVM协议进行故障定位.仿真结果表明,该机制不仅能够陕速定位多域全光网络中的域间、域内多链路故障,而且具有较高的故障定位率.     

基于GMPLS的智能光网络生存性研究

智能光网络ION是下一代光网络的发展趋势,高效及快速的生存性是ION最重要的特点之一.主要研究了基于通用多协议标记交换GMPLS的ION保护恢复管理机制,在对现有生存性算法进行分析比较的基础上,重点讨论了基于GMPLS的控制平面生存性机制并提出了一种处理节点失效的新思路,最后对基于GMPLS的智能光网络的恢复时间做了具体分析.     

IP over DWDM网络的生存性研究

探讨了IP over DWDM生存性的机制，研究了各个网络层的恢复特点以及不同层间相互作用对生存性的影响，明确了多层网络生存性的优点，从而得出光层能够提供最快的保护，较高的层能够提供智能恢复。最后提出了一种在光层的自动保护倒换的结构，这种保护能够优先考虑来自较高层的告警信息，使IP over DWDM网络做到智能化的快速恢复，为IP over DWDM网络的研究和建设提供了一定基础。     

光突发交换网络的生存性及保护恢复

光突发交换(OBS)是很有前途的一种光交换方式,其中的保护恢复策略增强了网络的生存性.介绍了OBS的原理、OBS中的保护和恢复机制及其特点,对OBS网络的保护恢复提出了一些技术要求,这有助于OBS网络生存性的真正实现.     

基于GMPLS的自动交换光网络生存性技术研究

能够提供高效快速的生存性是自动交换光网络的重要特点.介绍了自动交换光网络的生存性实现的过程和各种生存性机制,提出了基于通用多协议标签交换的自动交换光网络中标签交换路径端到端生存性的实现方案,并对恢复的时间具体的分析.     

多域光网络中考虑域间输出策略的分段共享保护算法

研究了多域光网络中的路由保护问题.在多域光网络中,域间路由的建立要遵从域间输出策略.在考虑域间输出策略的基础上提出了一种多域光网络中基于路径计算单元的分段共享保护算法.仿真表明,相比传统的基于路径计算单元的多域分段保护算法,该算法阻塞率低,平均保护切换时间短.     

A novel domain-by-domain survivable mechanism in multi-domain wavelength-division-multiplexing optical networks

In multi-domain wavelength-division-multiplexing (WDM) optical networks, the inter-domain routing is a challenge since each single-domain cannot view the full network topology. At the same time, survivability is also an important issue in optical networks since the failures of fiber links or network nodes may lead to a lot of traffic being blocked. In this paper, we study the survivability in multi-domain WDM optical networks, and propose a new survivable mechanism called load balanced domain-by-domain routing (LBDDR). In LBDDR, in order to obtain the efficient inter-domain survivable routes, we present the domain-by-domain routing (DDR) method which can find the intra-domain sub-working path and sub-backup path in each single-domain to form the inter-domain working path and backup path for each demand. In order to reduce the blocking probability, we present the load balanced routing method which can encourage the traffic to be uniformly distributed on the links with more free wavelengths. Simulation results show that, compared with conventional mechanism, LBDDR can obtain better performances.     

A novel multi-link fault-tolerant algorithm for survivability in multi-domain optical networks

With the large-scale deployment of optical network equipments, the problems of separated domains management and the multi-domain-based survivability have become the primary challenge in new generation intelligent optical networks. Aimed at resisting multi-link failures in multi-domain optical networks (MDON), a heuristic multi-link fault-tolerant (MLFT) algorithm for survivability in MDON is proposed in this article, which applied Hamiltonian cycle protection and segment-shared protection to establish a novel survivability strategy for either intra-domain??s or inter-domain??s multiple links, respectively. Furthermore, a new virtual-link mapping scheme and link-cost formulas are presented to encourage the appropriate routing selection and load balancing, which can also contributed to better resource utilization ratio and blocking ratio. Simulation results show that MLFT realizes the multi-link fault-tolerant survivability at a lower cost with better performances in redundancy ratio, blocking ratio, and computation complexity.     

Waveband Grooming based on Layered Auxiliary Graph in multi-domain optical networks

With the number of wavelengths on fibers keeps increasing, the size and the cost of Optical Cross-Connect (OXC) are greatly enhanced and then the control and management of optical switches become more and more complicated. Therefore, the technique called waveband switching is proposed to reduce the size and the cost of OXC; that is, to save the All-Optical (OOO) switching ports in OXC. However, the existing waveband switching algorithms are all limited in single-domain optical networks. Actually, with the scale of optical backbone keeps enlarging, the network is divided to multiple independent domains to perform the hierarchy routing for achieving the scalability. In order to reduce the size and the cost of OXC meanwhile to achieve the scalability in multi-domains, in this paper we propose a new heuristic algorithm called Waveband Grooming with Layered Auxiliary Graph (WGLAG) since the waveband grooming problem is the NP-hard to perform the inter-domain routing based on the virtual topology of multi-domain network and the intra-domain routing based on the physical topology of single-domain network. In intra-domain routing with waveband grooming of each single-domain, we propose the Layered Auxiliary Graph (LAG) that includes one virtual topology layer and multiple waveband-plane layers to compute a single-hop, or multi-hop or hybrid waveband route for each connection request based on the sub-path waveband grooming scheme. Simulation results show that, WGLAG not only can effectively save more switching ports to reduce the cost of OXC but also can obtain lower blocking probability than other algorithm.     

多域光网络联合路由保护算法

研究了多域光网络中的路由保护问题。为了避免多域光网络通路保护二步算法可能导致的多域陷阱问题,提出了一种基于Suurballe算法扩展的多域联合路由保护算法。仿真表明,相比传统的多域通路保护二步算法,该算法资源利用率高,阻塞率低,平均每连接跨域数小。     

A novel segment-shared protection algorithm based on dynamic domain-sequencing scheme for multi-domain optical mesh networks

Survivability has been widely recognized as an important design issue for optical networks. In practice, as the network scale keeps expanding, this design problem becomes more critical. Due to scalability and domain privacy, designing the protection scheme in multi-domain networks is more difficult than that in single domain networks. The path computation element (PCE) is known as an efficient architecture to compute optimal traffic engineering (TE) paths in multi-domain multilayer networks. Based on the PCE architecture, we first propose a new dynamic domain-sequencing scheme that considers the load balance of inter-domain links and then propose an improved segment-shared protection approach called DDSP. It can provide 100% protection ability for multiple failures that each single domain has only one failed link. Finally, the protection based on the optimal dynamic domain-sequencing scheme, called OPT, is designed, to evaluate performance of our algorithm and to provide the good bounding for the dynamic domain-sequencing scheme with limited intra TE information. Simulation evaluation shows that the proposed scheme is effective in multi-domain path protection with more efficient resource utilization, lower blocking probabilities and less inter-domain cost. Furthermore, the performance of it is near to OPT.     

An adaptive inter-domain PCE framework to improve resource utilization and reduce inter-domain signaling

Upcoming broadband commercial and scientific applications are now demanding high bandwidth pipes across multiple domains with guaranteed Quality of Service (QoS). Recent research initiatives such as the Path Computation Element (PCE) framework are focusing on the development of scalable multi-domain QoS provisioning frameworks, especially within the emerging carrier grade transport technologies based on layer-2 tunnels. QoS provisioning across multiple domains requires that QoS parameters for available transit paths inside a domain be advertised in the inter-domain routing algorithms, while the dynamic inter- and intra-domain connections vary the available resource, and hence require frequent inter-domain updates. The signaling load on the other hand hampers the scalability of the inter-domain routing mechanisms. We propose the use of an adaptive partitioning framework, which can effectively use network resources and at the same time stabilize the advertised domain topologies and thus path advertisements. Our method partitions network resources by pre-reserving resources for inter-domain transit traffic, and uses policies to modify the resource partitioning in order to maintain the available transit capacity between specified bounds. We show by simulations that the proposed mechanism can reduce inter-domain signaling load by 10%-20% and reduce overall blocking inside a domain by creating a trade-off between available resources for intra-domain connections and inter-domain transit connections. The reduction in inter-domain signaling and blocking can be used as a building block to design scalable QoS routing systems for carrier grade transport networks.     

Multi-domain grooming algorithm based on hierarchical integrated multi-granularity auxiliary graph in optical mesh networks

With the size of traffic demands ranges from sub-wavelength-level to wavelength-level, traffic demands need to be aggregated and carried over the network in a cost-effective manner to make sure that the resources are utilized effectively. Therefore, the technique called multi-granularity grooming is proposed to save the cost by reducing the number of switching ports in optical cross-connects. However, the existing multi-granularity grooming algorithms are mostly limited in single-domain optical networks. Since the current optical backbone keeps enlarging and is actually divided to multiple independent domains for achieving the scalability and the confidentiality, it is necessary to study the multi-granularity grooming in multi-domain optical networks. In this paper, we propose a new heuristic algorithm called hierarchical multi-domain multi-granularity grooming (HMMG) based on hierarchical integrated multi-granularity auxiliary graph (H-IMAG) to reduce the total number of optical switching ports. The H-IMAG is composed of the inter-domain virtual topology graph (VTG) and the intra-domain integrated layered auxiliary graph (ILAG), where VTG includes a wavelength virtual topology graph (WVTG) and a waveband virtual topology graph (BVTG), and ILAG includes a wavelength layered auxiliary graph (WLAG) and a waveBand layered auxiliary graph (BLAG). Then, we can groom the sub-wavelength-level demands into lightpaths based on WVTG and WLAG and groom the wavelength-level demands into high-capacity wavebands based on BVTG and BLAG. Simulation results show that performances of H-IMAG can be significantly improved compared with previous algorithm.     

A new framework for GLIF Interdomain Resource Reservation Architecture (GIRRA)

Many existing and emerging Scientific high-end applications (E-science) require end-to-end circuits interconnecting Grid resources for large data transfers. A few advanced networks, mainly National Research and Education Networks (NRENs), such as Surfnet, National Lambda Rail and Internet 2, now provide mechanisms for end-users to reserve and provision lightpaths via middleware referred to as Network Resource Mangers (NRMs). Although, some progress has been made in automated intra-domain lightpath services, inter-domain lightpath provisioning still requires manual intervention and presents several key challenges such as scalability of topology information exchanged, consistency and scalability of information model, security of access to the resources, hybrid networking and multi-layer lightpaths, and accounting and billing. In this paper, we describe a new architectural framework called Global Lambda Integrated Facility (GLIF) Interdomain Resource Reservation Architecture (GIRRA) with the goal to provide an integrated response to these challenges. We propose a new approach to model GLIF network domains and GOLEs as virtual switches and to describe their behavior, functionality, policy capabilities, and topology aggregation. We define an inter-domain path computation model to determine paths that meet constraints and access policy restrictions. We propose a security framework for authentication and authorization of users and a model for accounting and billing that aims to provide easy and secure access to the resources. Key aspects of the GIRRA solution are that it focuses on the inter-dependence between different challenges of inter-domain path provision, and it is built around already existing solutions for intra-domain resource provisioning.     

Cross-domain access control policy mapping mechanism for balancing interoperability and autonomy

Cross-domain access control can improves interoperability but reduces intra-domain autonomy.To balance inter-domain interoperability and intra-domain autonomy,a cross-domain access control policy mapping to the problem of multi-objective integer optimization programming was formulated.Both the maximization of inter-domain interoperability and the minimization of intra-domain autonomy were taken as the objectives.Further,seven constraints were designed to prevent typical cross-domain conflicts.To solve the optimization problem,a constrained NSGA-III algorithm was proposed.The experimental results show that the proposed algorithm can quickly converge and accurately find the policy mapping even in the large-scale datasets.     

P-cycle Protection in multi-domain optical networks

Providing resilient inter-domain connections in multi-domain optical GMPLS networks is a challenge. On the one hand, the integration of different GMPLS domains to run traffic engineering operations requires the development of a framework for inter-domain routing and control of connections, while keeping the internal structure and available resources of the domains undisclosed to the other operators. On the other hand, the definition of mechanisms to take advantage of such automatically switched inter-domain connectivity is still an open issue. This article focuses on the analysis of applicability of one of these mechanisms: P-cycle-based protection. The proposed solution is based on the decomposition of the multi-domain resilience problem into two sub-problems, namely, the higher level inter-domain protection and the lower level intra-domain protection. Building a P-cycle at the higher level is accomplished by certain tasks at the lower level, including straddling link connection, capacity allocation and path selection. In this article, we present several methods to realize inter-domain P-cycle protection at both levels and we evaluate their performance in terms of availability and spent resources. A discussion on a proposal of implementation of signalling based on extensions of existing protocols such as RSVP-TE and the PCE architecture illustrates the practical viability of the approach.