带跳数限制的抗毁性网络设计

在网络设计中,为了保证网络服务质量,需要对网络节点间的跳数进行限制.同时网络设计还必须考虑一定的抗毁性要求.提出了使用生成树优化算法来求解某些抗毁性网络设计的难题.生成树优化算法较圆满地解决了既有连通度要求又有跳数限制的抗毁性网络设计问题.该算法不仅具有较强的实际应用价值,也对推动抗毁性网络的研究有十分重要的意义.     

通信网络可靠性评估的一种算法

本文分别对等故障率和不等故障率链路所组成的通信网的可靠性进行分析,提出相应的评估算法,并用实例说明算法执行过程。1、对等故障率链路所组成的通讯网,依据图论统计含网络图所有顶点的支撑子图的数目,然后给出通信网可靠性的估算公式。2、对不等故障率链路组成的通讯网,首先给出生成网络图的所有支撑树的算法,并把其定义为成功函数,利用排它算子,给出评估通信网可靠性的算法。     

基于改进生成树优化算法的抗毁性网络设计研究

针对当前通信网络抗毁性设计问题,以连通度和跳数作为评价指标,建立了满足指标约束条件且成本开销最小化的网络优化设计模型,并在此基础上提出了改进生成树优化算法求解该模型。仿真结果表明,该算法与生成树优化算法相比,能够更好地权衡各项指标,在确保抗毁性条件下可有效降低成本开销。对于通信网络,特别是大型网络的规划及优化设计,该算法具有实际应用价值和可操作性。     

一种基于选路拓扑的抗毁性评估模型

网络抗毁性是网络可靠性研究的重要内容.本文提出了一种基于选路拓扑的网络抗毁性研究方法,通过构造选路拓扑建立链路集影响度评估模型,给出了面向网络实际通讯能力的抗毁性概念定义及测度表达,提出了一种影响网络抗毁度的关键链路集选择启发式算法,对于网络抗毁能力表达更加精确.     

WDM全光网络中实时组播的分布式路由与波长分配算法

在WDM网络中，由于每条链路上可用波长是动态变化的，在考虑波长转换延迟的条件下，实现实时组播连接的路由与波长分配是十分困难的．假定WDM网络中每条链路有多根光纤，只有部分结点具有波长转换器且波长转换时间是不可忽略的，据此提出了一种用于建立实时组播连接的分布式路由与波长分配算法．该算法以Prim最小生成树算法为基础，生成一棵满足给定延迟时限的最小成本树．当最小成本树不能包括所有目的结点时，对剩余目的结点生成一棵最短延迟树，然后合并两棵树得到一棵组播树．波长分配使用最少波长转换和负载平衡策略．     

基于链路重构策略的网络抗毁性优化研究

网络抗毁性优化是目前通信网络研究的重要领域。为实现对通信网络的抗毁性优化,提高网络抗打击能力,对网络抗毁性与网络聚合度之间的关系进行分析,利用该结论提出了网络抗毁性优化的链路重构策略。一是通过对传统HBF-α算法链路重构策略的调整,提高了网络优化效果,且算法复杂度低、收敛速度快、效率较高;二是结合部分通信网络实际要求,提出了保证节点度不变的重构策略,以网络聚合度为目标函数,使用模拟退火算法有效解决了HBF-α策略中局部最优解问题。并分析对比两种优化方案的优化程度以及时间开销。对于规模较大,且各节点建链能力较强的网络采用方案一优化;对规模较小,且各节点建链能力有限的网络采用方案二优化,可以达到较好的网络抗毁性优化效果。     

一种通信网络抗毁性评价的改进模型

分析了现代战场通信网抗毁性评价的需求,针对现有通信网抗毁性测度评价模型无法准确评价网络抗毁性测度和节点重要性,以及不同节点数的网络间抗毁性的问题,利用基于最短路径数和跳面节点法节点重要性多指标评价方法对该模型进行改进。在此基础上,提出一种基于节点的全网平均等效抗毁性测度的网络抗毁性评价模型,并验证了模型的有效性。     

基于路由数目的通信链路重要性分析

为了分析通信网络中通信链路对端到端通信的重要程度,提出一种基于路由数目的链路重要性计算方法。该方法采用一种快速算法,寻找出端到端的所有通信路由,再通过比较不同通信链路的损坏使端到端之间传输路由减少的数目,判断不同通信链路对端到端通信的重要性,如果某通信链路损坏导致路由减少越多,则该链路越重要。计算实例表明,该方法计算简单,易于编程实现,具有一定的实用性和有效性。     

WDM网络中实时组播的分布式优化RWA算法

在WDM网络中,由于每条链路上可用波长是动态变化的,在考虑波长转换延迟时间的条件下,实现实时组播连接的路由选择与波长分配是十分困难的。论文提出了一种用于建立实时组播连接的分布式路由选择与波长分配算法。该算法将路由选择与波长分配统一进行,大大减少连接的建立时间。组播路由算法以Prim最小生成树算法为基础,生成一棵满足给定延迟时限的最小成本树。波长分配使用最少波长转换和同一波长最长使用策略。     

WDM网络中实时组播的分布式路由与波长分配算法

在WDM网络中,由于每条链路上可用波长是动态变化的,在考虑波长转换延迟时间的条件下,实现实时组播连接的路由与波长分配是十分困难的。该文提出了一种用于建立实时组播连接的分布式路由与波长分配算法。该算法将路由与波长分配统一进行,大大减少连接的建立时间。组播路由算法以Prim最小生成树算法和K-度宽度优先搜索方法为基础,生成一棵满足给定延迟时限的最小成本树。波长分配使用最少波长转换和负载平衡策略。     

Self-stabilizing group communication in directed networks

This paper presents the first self-stabilizing group membership service, multicast service, and resource allocation service for directed networks. The first group communication algorithm is based on a token circulation over a virtual ring. The second algorithm is based on construction of distributed spanning trees. In addition, a technique is presented that emulates, in a self-stabilizing fashion, any undirected communication network over strongly connected directed networks, is presented. A resource allocation asynchronous algorithm for strongly connected directed networks is presented.Received: 23 July 2003, Published online: 29 June 2004Partially supported by NSF Award CCR-0098305, IBM faculty award, STRIMM consortium, and Israel ministry of defense.     

A Distributed Algorithm for Constructing Minimal Spanning Trees

Most algorithms for constructing minimal spanning trees are sequential in operation. Distributed algorithms for constructing these trees operate both concurrently and asynchronously, and are useful in store-and-forward packet-switching computer-communication networks where there is typically no single source of control. The difficulties in designing such algorithms arise from communication and synchronization problems. This paper discusses these problems and describes the first distributed algorithm for constructing minimal spanning trees. This algorithm and the principles and techniques underlying its design will find application in large communication networks and large multiprocessor computer systems.     

Hierarchical spanning trees and distributing on incomplete hypercubes

Incomplete hypercubes are gaining increasing attention as one of the possible solutions for the limitation on the number of nodes in the hypercubes. Distributing, in which one node sends distinct messages to distinct nodes, and its reverse operation are frequently used operations on data parallel computation. In this paper, we propose two types of spanning trees in incomplete hypercubes (composed of an n-cube and a k-cube): the binomial hierarchical spanning tree-binomial HST, and the balanced hierarchical spanning tree-balanced HST, for distributing (and its reverse operation). Distributing algorithms based on a balanced HST take better advantage of overlap between communication ports, or have speedup up to k/2 or n/2 over that based on the binomial HST when concurrently communication on all ports are possible, from the view point of communication complexity. An algorithm to construct hierarchical spanning trees in general incomplete hypercubes, which consist of an arbitrary number of nodes, is also devised.     

网络可存活生成树的快速恢复算法

如何应对网络链接失效是具有挑战性的问题之一,通常采用包含两棵生成树的可存活连接来预防链接失效。由于网络数据传输速率的高速增长,当两棵生成树的共享链接失效时,可存活连接中的生成树将全部失效。针对可存活连接中共享链接的失效提出了一种快速恢复算法,该算法通过搜索失效链接的可替换链接集,将失效概率最小的链接加入原可存活连接中的生成树,生成新的可存活连接。实验结果表明,该算法能够在显著降低恢复时间和时间复杂度的情形下,同时保证可存活连接的存活度接近当前网络的最优存活度。当网络节点数在10～100变化时,提出的算法比现有算法在恢复时间上的平均优化高达34.42%,同时在存活度上的误差不超过1%。     

字典乘积网络的支撑树计数

支撑树个数是边失效下网络可靠性分析与设计的一个重要性能参考指标,本文利用字典乘积的方法来构建网络,通过这种方法我们很容易由若干特定规模较小网络来构建规模较大的网络,并得到它的一个紧的支撑树计数解析公式,这样的计数公式仅仅依赖于小网络的性能参数,如:结点的度数、小网络的阶数、小网络的支撑树数目.     

Multicast in Wormhole-Switched Torus Networks Using Edge-Disjoint Spanning Trees

A tree-based multicast algorithm for wormhole-switched networks which makes use of multiple edge-disjoint spanning trees is presented. The disjoint spanning-tree multicast, or DSTM, algorithm provides deadlock-free multicast routing that is fully compatible with unicast. The application of the DSTM algorithm to 2-dimensional torus networks is considered. A family of constructions of two spanning trees in the torus is given along with a formal proof of their edge-disjointness. Two constructions from this family are selected and shown to produce diameters no greater than twice that of the torus. Flit-level simulation results are presented to show that DSTM outperforms the best single spanning tree multicast approach by up to a factor of two. The DSTM algorithm is also simulated for different spanning tree constructions. The results show that our novel tree construction is significantly better for multicast than those produced by a general tree construction method that applies to arbitrary-topology networks (J. Roskind and R. Tarjan, Math. Oper. Res.10 (Nov. 1985), 701–708). Finally, two approaches to providing single link fault tolerance with DSTM are presented and evaluated.