光纤Mesh网络动态组播业务疏导算法

针对当前低速组播业务请求与光网络高速波长传输容量的问题,基于光网络组播业务疏导模型,提出动态组播业务疏导算法,将新的组播业务请求疏导到已建立的光组播树上,达到提高网络资源的利用率、降低组播业务连接阻塞概率的目的。仿真结果表明,该算法可有效地改善网络性能。     

基于分布式路径计算单元的多域光网络组密钥管理方案

针对分布式路径计算单元（PCE）架构下多域光网络的通信特点和密钥管理需求，提出一种该架构下的组密钥管理方案。首先使用超图理论对分布式PCE架构下的多域光网络密钥关系进行建模得到两层式密钥超图；然后在自治域层采用基于自认证公钥密码体制和成员过滤技术的密钥管理方法，在PCE层采用基于椭圆曲线密码体制的组密钥协商方法；最后完成密钥的产生、分发、更新和动态管理，较好地解决了成员的私钥保密性问题和第三方节点的冒充问题，减少了密钥更新时的计算开销。性能分析显示，该方案具有前向安全性、后向安全性、密钥保密性和抗合谋攻击等特点，与典型的分散式方案相比，在密钥存储量、加解密次数和通信开销等方面取得了较优的性能。     

一种REM算法辅助的分层组播流量控制方案

基于分层组播中公平速率分配算法实施过程中存在的问题以及分层组播协议策略中同步点的优化问题,提出了将主动队列管理算法REM作为对端系统的辅助加入到分层组播流量控制中,将分层组播同步点策略、满足Max-Min公平性要求的速率分配算法以及基于REM的显式拥塞指示技术有机地结合起来,设计了一种基于速率的、由接收者和发送者混合驱动的分层组播流量控制方案。仿真实验结果表明该方案使得分层多速率组播在保证会话内、会话间公平性的前提下,提高了流量控制机制的高效性和对网络状态适应的灵敏性。     

无线Mesh网络中基于业务价值的组播带宽分配方案

高延迟及低效益是无线Mesh网络中开展流媒体业务面临的主要问题。为解决该问题,首先赋予组播业务价值,该值反映了业务的网络优先级及效益优先级,并提出一个基于组播价值优先级的组播带宽分配方案。该方案第一阶段实施基于价值优先级的不区分业务类型的静态分配,通过对高价值业务的优先调度,实现了组播价值最大化及带宽效益最大化。在拥塞时,实施第二阶段的基于业务带宽需求调整及抢占的动态分配,保证了低时延约束业务的服务质量。仿真与常见算法的比较表明,所提出的方案在保证业务网络服务质量的同时,能实现带宽效益最大化。     

基于网络编码的光组播树优化RWA研究

为了降低网络负载均衡率与平均阻塞率,提出了基于分层图的具有网络编码能力的共享光组播树算法。通过对该算法的仿真表明,具有网络编码能力的共享光组播树在使用的光路数、平均阻塞率以及网络负载均衡率上要优于共享树。最后作了总结并指出将来的研究方向。     

基于边缘簇组播树构造算法的分析与改进

在分析IP域中支持QoS的基于边缘簇的组播树构造算法的基础上,针对该算法生成的组播树的总体路径费用较高的问题,提出了一种改进的基于边缘簇的组播树构造算法IECT,该算法可在承载组播流量的网络核心域构造出总体路径费用较小的组播分发树。     

分层组播中INTER-SESSION FAIRNESS问题的分析与对策

通过一组实验结果分析现有分层多速率组播协议的速率控制机制中存在的会话间公平性问题,提出在组播分层解决方案中,以一种基于Max-Min公平性的速率分配计算算法,在网络状态改变时得到共存于网络环境中的各虚会话的公平速率分配集,并辅以二分法,对取值于连续数据集合上的速率分配集进行不同粒度上的离散化整合.实验结果表明该方案使得分层组播在保证会话间公平性的前提下,提高了流量控制的高效性和灵敏性.     

基于代理的分层组播实现方案

针对IP组播和应用层组播的特点,将两者组合使用,提出一种基于分层组播的业务实现方案。在局域范围内形成若干IP组播域,在每个IP组播域内设置组播代理,数据源通过IP组播代理完成数据的转发,可有效地降低组播树的更新频率,减少组播造成的网络开销,同时提高组播业务流的可控性。     

分层组播中MAX-MIN公平速率分配算法的运用

以分层多速率组播解决方案为研究目标,针对多速率组播与TCP单播共存网络的公平性问题,通过在分层组播中应用max min公平速率分配算法来得到各虚会话的公平速率,并采用二分法对速率集合进行不同粒度上的整合,给出了具体的分层解决策略,从而为异构网络环境中分层多速率组播在公平性前提下的有效实施提供了保障。     

一种基于网络编码的组播路由算法

网络编码是2000年提出的一种新算法,其主要优点是使组播传输速率能达到理论上限值.介绍了传统组播路由算法的局限性,分析了现有网络编码算法的优点和不足,在某个改进的网络编码数学模型上,提出了一种静态分布式分层网络编码SDLNC算法(Static Distributed Layered Network Coding).模拟实验表明,该算法可以显著提高组播路由的数据传输速率.     

Protecting multicast services in optical internet backbones

Many applications in the future Internet will use the multicasting service mode. Since many of these applications will generate large amounts of traffic, and since users expect a high level of service availability, it is important to provision multicasting sessions in the future Internet while also providing protection for multicast sessions against network component failures. In this paper we address the multicast survivability problem of using minimum resources to provision a multicast session and its protection paths (trees) against any single-link failure. We propose a new, and a resource efficient, protection scheme, namely, Segment-based Protection Tree (SPT). In SPT scheme, a given multicast session is first provisioned as a primary multicast tree, and then each segment on the primary tree is protected by a multicast tree instead of a path, as in most existing approaches. We also analyze the recovery performance of SPT and design a reconfiguration calculation algorithm to compute the average number of reconfigurations upon any link failure. By extending SPT to address dynamic traffic scenarios, we also propose two heuristic algorithms, Cost-based SPT (CB_SPT) and Wavelength-based SPT (WB_SPT). We study the performance of the SPT scheme in different traffic scenarios. The numerical results show that SPT outperforms the best existing approaches, optimal path-pair-based shared disjoint paths (OPP_SDPs). SPT uses less than 10% extra resources to provision a survivable multicast session over the optimal solution and up to 4% lower than existing approaches under various traffic scenarios and has an average number of reconfigurations 10–86% less than the best cost efficient approach. Moreover, in dynamic traffic cases, both CB_SPT and WB_SPT achieves overall blocking probability with 20% lower than OPP_SDP in most network scenarios.     

A survivable routing algorithm with differentiated domain protection based on a virtual topology graph in multi-domain optical networks

In this paper, we propose a novel differentiated domain protection (DDP) scheme to address survivability in multi-domain optical networks. Survivable routing in multi-domain networks is a challenging algorithmic problem because it requires choosing links that provide adequate protection both between domains and within domains that may offer different protection services. To satisfy the survivability requirements of different domains, DDP considers differentiated protection schemes, i.e., dedicated protection, shared protection, or no protection in different domains. In order to respect the principle of transparent management in multiple domains, DDP abstracts a multi-domain optical network to a virtual topology graph (VTG) for solving routing between domains. Simulation results show that DDP, unlike traditional schemes, can provide trade-off between protection methods and also allows better resource utilization.     

Multicast protection scheme in survivable WDM optical networks

The protection design is a key issue in survivable wavelength division multiplexing (WDM) optical networks. Most researches focused on protecting unicast traffic against the failure of a single network component such as a link or a node. In this paper, we investigate the protection scheme for multicast traffic in meshed WDM optical networks under dual-link failure consideration, and propose a novel protection algorithm called shared segment protection with reprovisioning (SSPR). Through dynamically adjusting link-cost according to the current network state, SSPR establishes a primary light-tree and corresponding link-disjoint backup segments for each multicast connection request. A backup segment can efficiently share wavelength capacity of its working tree or the common resource of other backup segments. Capacity reprovisioning establishes new segments for the vulnerable connections after a link failure and tolerates following link failures. The simulation results show that SSPR not only can make good use of wavelength resources and protect multicast sessions against any single-link failure, but also can greatly improve the traffic restorability in the event of dual-link breakdown.     

A QoS Multicast Routing Algorithm Working with Imprecise State Information

In large networks, maintaining precise global network state information is almost impossible. Many factors, including non-negligible propagation delay, infiequent link state update due to overhead concerns, link state update policy, and hierarchical topology aggregation, have impacts on the precision of the network state information. The existing QoS multicast routing algorithms do not provide satisfactory performance with imprecise state information. In this paper, we propose a distributed QoS multicast routing scheme based on traffic lights, called QMRI algorithm, which can probe multiple feasible tree branches, and select the optimal or near-optimal branch through the UR or TL mode for constructing a multicast tree with QoS guarantees if it exists. The proposed algorithm considers not only the QoS requirements but also the cost optimality of the multicast tree. Extensive simulations show that our algorithm achieves high call-admission ratio and low-cost multicast trees with modest message overhead. The algorithm can tolerate high degree of state information imprecision.     

基于网络编码的无线数据流保护

网络编码是一种能显著提升网络传输性能的通信机制。而当前将网络编码应用于无线数据流保护以提高网络生存能力方面的研究还没达到如此完备的程度。本论文旨在建立基于网络编码的无线数据流保护模型,验证并实现建立进行网络编码的网络拓扑的算法。验证网络编码应用于无线数据流保护可以提高网络生存能力、减少网络资源消耗并具有远胜于传统保护的时效优势。在网络中部署和实施网络编码,必须建立适用于网络编码的传输节点拓扑并选择合适的编码模式。对于后者,许多学者出了有效的解决方法,而对于网络拓扑规划问题的研究则相对较少。鉴于此,本文论证了一种编码树拓扑结构算法,该算法与现有的编码模式一起,能够构成完整的网络编码无线数据流保护方案。通过理论论证可以证明应用网络编码方法可以在保护时节约网络资源。仿真实验表明,与传统的链路保护模式相比,使用网络编码的无线数据流保护方法具有更小的时延,也即具有传统保护方法没有的时间优势。     

时间同步网的可生存性增强

研究大规模时间同步网的可生存性问题．时间同步网通过各节点的自主配置,拓扑结构不再是静态的、层次型的,而成为动态的网络结构,增强网络的可生存性．提出搜索世界的概念,针对时间同步网络建立了基于搜索世界的BA模型,并对模型进行优化,使时间同步网络的可生存性更高．动态的网络拓扑在部分节点失效以后受影响的节点能够自愈,给出了节点自愈算法,使节点自愈时对网络负载的影响比较小．     

多域光网络中应用混合拓扑聚合的分段保护算法

研究了多域光网络中的路由保护问题;为了克服多域光网络中可扩展性约束,提出了一种混合拓扑聚合方法。该方法结合了全连通和生成树拓扑聚合的优点,在网络中需要存储和发布的链路状态信息与聚合信息反映实际物理拓扑的精确性之间进行了折中;然后在此混合拓扑聚合方法的基础上,提出了一种基于查询机制的多域分段保护算法。仿真表明,相比传统的多域保护算法,该算法阻塞率低,可扩展性好。     

On fair and optimal multi-source IP-multicast

We investigate the problem of maximizing multicast throughput under a fairness constraint. Multiple server nodes wish to communicate to their intended set of client nodes over a shared network infrastructure. Our goal is to devise distributed algorithms to construct multicast sessions, one for each server node, such that (a) the network infrastructure is optimally utilized and (b) the network resources are fairly distributed between multicast sessions, i.e., no individual session claims more than a prescribed share of the network bandwidth resources. We are particularly interested in multi-tree multicast strategies in which every multicast session may contain many multicast trees. We show how the use of multiple trees increases network throughput and the load distribution in the network. We propose a class of round-robin algorithms that are based on successive selection of multicast trees for each multicast session, in a loosely cooperative, yet distributed fashion. Our best algorithm, the Cooperative Shortest Path Tree Packing (CSPTP) algorithm, performs well in a variety of scenarios, ranging from very sparse to dense applications. Through extensive simulations on random networks, we compare the performance of our algorithms with those commonly used in IP-multicast as well as theoretical upper bounds derived from network coding formulations. We show that the CSPTP can improve the throughput, and often achieves about 90% of the theoretical upper bound.     

IP／DWDM光因特网路由选择机制的研究

The requirements of IP/DWDM optical Internet routing are analyzed. Guaranteeing QoS, survivability and last routing, and supporting multicast and making lull use of the resources of network are the basic requirements for it. Point out that QoS and survivability are the most important two keys to optical Internet routing. Summarize the common implementations which are used to satisfy these requirements. At last, point out the further steps that should be taken.