Exact Algorithm to Solve the Minimum Cost Multi-Constrained Multicast Routing Problem

The optimal solution of the multi-constrained QoS multicast routing problem is a tree-like hierarchical structure in the topology graph. This multicast route contains a feasible path from the source node to each of the destinations with respect to a set of QoS constraints while minimizing a cost function. Often, it is a tree. In other cases, the hierarchies can return several times to nodes and links of the topology graph. Similarly to Steiner problem, finding such a structure is an NP-hard problem. The usual tree and topology enumeration algorithms applied for the Steiner problem cannot be used to solve the addressed problem. In this paper, we propose an exact algorithm based on the Branch and Bound principle and improved by the Lookahead technique. We show relevant properties of the optimum hierarchy permitting efficient pruning of the search space. To our knowledge, our paper is the first to propose an exact algorithm for this non-trivial multi-constrained optimal multicast route computation. Simulations illustrate the efficiency of the proposed pruning operations. The analysis of the execution time shows that in simple topologies and with tight QoS constraints the exact algorithm requires relatively little execution time. With loose constraints the computation time cannot be tolerated even for off-line route computation. In these cases, the solution is close to a Steiner tree and heuristics can be applied. These results can serve as basis for the design of efficient, polynomial-time routing algorithms.

Algorithm for multi-constrained path selection based on experimental analysis

It is a challenging problem to provide quality-of-service （QoS） guarantees in next generation high-speed network, and the QoS routing is one of the key issues of the problem. For the problem of multi-constrained QoS routing in high-speed network, especially under the inaccurate link state information, the success ratio of the different constraint combination is analyzed statistically, and a constraint analysis method based on the computer simulation is proposed. Furthermore, the approximately equal loose-tight order relation between each two constraints is constructed, and then an algorithm based on the experimental analysis is presented. Finally, the simulation result demonstrates that the algorithm has the higher success ratio, and the theoretical analysis proves its correctness and universality.

SIMULATED ANNEALING BASED POLYNOMIAL TIME QOS ROUTING ALGORITHM FOR MANETS

Multi-constrained Quality-of-Service (QoS) routing is a big challenge for Mobile Ad hoc Networks (MANETs) where the topology may change constantly. In this paper a novel QoS Routing Algorithm based on Simulated Annealing (SA_RA) is proposed. This algorithm first uses an energy function to translate multiple QoS weights into a single mixed metric and then seeks to find a feasible path by simulated annealing. The pa- per outlines simulated annealing algorithm and analyzes the problems met when we apply it to Qos Routing (QoSR) in MANETs. Theoretical analysis and experiment results demonstrate that the proposed method is an effective approximation algorithms showing better performance than the other pertinent algorithm in seeking the (approximate) optimal configuration within a period of polynomial time.

Improved ant colony-based multi-constrained QoS energy-saving routing and throughput optimization in wireless Ad-hoc networks

In order to establish a route supporting multi-constrained quality of service（QoS）, increase network throughput and reduce network energy consumption, an improved ant colony-based multi-constrained QoS energy-saving routing algorithm（IAMQER） is proposed. The ant colony algorithm, as one of the available heuristic algorithms, is used to find the optimal route from source node to destination node. The proposed IAMQER algorithm, which is based on the analysis of local node information such as node queue length, node forwarding number of data packets and node residual energy, balances the relationship between the network throughput and the energy consumption, thus improving the performance of network in multi-constrained QoS routing. Simulation results show that this IAMQER algorithm can find the QoS route that reduce average energy consumption and improves network packet delivery ratio under the end-to-end delay and packet loss ratio constraints.

Genetic algorithm for pareto optimum-based route selection

A quality of service （QoS） or constraint-based routing selection needs to find a path subject to multiple constraints through a network. The problem of finding such a path is known as the multi-constrained path （MCP） problem, and has been proven to be NP-complete that cannot be exactly solved in a polynomial time. The NPC problem is converted into a multiobjective optimization problem with constraints to be solved with a genetic algorithm. Based on the Pareto optimum, a constrained routing computation method is proposed to generate a set of nondominated optimal routes with the genetic algorithm mechanism. The convergence and time complexity of the novel algorithm is analyzed. Experimental results show that multiobjective evolution is highly responsive and competent for the Pareto optimum-based route selection. When this method is applied to a MPLS and metropolitan-area network, it will be capable of optimizing the transmission performance.

A novel and effective multi-constrained QoS routing scheme in WMNs

Multi-constrained quality of service(QoS)routing aims at finding an optimal path that satisfies a set of QoS parameters,as an NP complete problem,which is also a big challenge for wireless mesh networks(WMNs).Heuristic algorithms with polynomial and pseudo-polynomial-time complexities are often used to deal with this problem.However,existing solutions,most of which suffered either from excessive computational complexities or from low performance,were proposed only for wired networks and cannot be used directly in wireless mesh networks.In this paper,we propose a novel routing scheme based on mean field annealing(MFA-RS)to solve this problem.MFA-RS first uses a function of two QoS parameters,wireless link’s delay and transmission success rate as the cost function,and then seeks to find a feasible path by MFA.Because MFA-RS uses a set of deterministic equations to replace the stochastic process in simulated annealing(SA)and uses saddle point approximation in the calculation of the stationary probability distribution at equilibrium,the convergence time is much less than the routing scheme based on SA(SA-RS).Simulation results demonstrate that MFA-RS is an effective algorithm and is very fit for WMNs.

因特网路由协议研究综述

路由器是因特网组网的关键设备,而路由器的主要功能是运行路由协议,并与其它路由器交换路由信息形成本机上的路由表,同时根据路由表的信息正确转发分组。在Internet中,路由协议至关重要,它直接影响网络的性能。近年来,路由协议领域中开展了大量的研究工作,有力地推动了Internet的发展。本文总结了当今Internet上所使用的单播、组播、QoSR、移动等路由协议的研究现状,并分析了进一步的研究方向。

引入梯度下降的蚁群算法求解多约束服务质量路由

针对目前多数改进蚁群算法求解多约束服务质量路由(Qo SR)存在收敛速度慢、易陷入局部最优从而效率不高的问题,提出一种引入梯度下降的蚁群算法(ACAGD)。该算法将梯度下降法引入到蚁群的局部搜索中,结合残余信息素,综合决定蚂蚁的下一跳选择策略。蚁群不仅以一定概率按照信息素浓度搜索下一跳,还将以一定概率按照梯度下降法搜索下一跳,从而降低传统蚁群算法容易陷入局部最优的可能性。利用Waxman网络模型随机生成不同路由节点数量的网络拓扑进行仿真实验。实验结果表明,ACAGD相比其他改进蚁群算法,能够在收敛速度不受影响的情况下,取得综合代价相对较低的路由,且算法的稳定性较好。

分布式系统中的数据邮递QoS模型

传统单播网络传输一般采用Dijkstra最短路径算法建立点到点的最小路径计算。针对此,改进Dijkstra算法,提出一种平衡网络负载的服务质量路由模型,解决分布式数据库系统中数据动态、实时交换路由的问题。实验结果表明,该模型具有较好的稳定性,能避免网络拥塞。

一种基于OSPF扩展的预计算QoS路由算法研究

在一个MPLS域,LSPs的建立需要QoS路由协议分发QoS相关的信息和执行QoS路径选择,但是传统的OSPF不支持QoS路由。本文提出并详细讨论了一种OSPF-QoSR路由机制,它是对OSPF路由协议的扩展,基于网络的动态可用带宽资源和流的QoS请求来决定流的QoS LSPs。仿真证明,该机制在丢包率、链路利用率、延时方面的性能优于只考虑最短路径的OSPF。

一种多约束服务质量路由算法

下一代网络服务质量要求解决多约束服务质量路由问题.在分析了服务质量路由特点及相关工作的基础上,提出服务质量路由新计算方法.方法基于路径计算,首先计算最少跳路径,然后利用非线性花费函数进行求解并判断约束路径,最后求出优化多约束路径.通过对网络拓扑状态仿真结果表明,该算法能快速求解在多约束条件下优化路径,约束参数扩展性好.

服务质量路由算法仿真平台的设计与实现

下一代网络服务质量要求解决多约束服务质量路由问题。在分析服务质量路由特点及相关工作的基础上,设计服务质量路由算法的仿真平台。仿真平台基于随机网络模型,结合Waxman方法设计随机连接的产生方法,并通过深度优先搜索遍历算法来检查图的连通性。通过对网络拓扑状态仿真结果表明,该平台能嵌入各种多约束路由算法并进行仿真实现。

多约束QoS路由算法综述

保证服务质量的QoS路由(Quality of Service Routing)是网络中解决QoS问题的一项关键技术。QoS路由的主要目标是为接入的业务选择满足服务质量要求的传输路径,同时保证整个网络资源的有效利用。度量参数选择问题、寻路问题和路由信息不准确问题是QoS路由中的几个主要研究内容。多约束QoS路由算法通常是NPC问题,本文先对QoS路由中的问题进行分类,再对当前研究的一些多约束QoS路由算法进行了归纳与分析。这些算法对于在Internet中实现QoS有着重要的指导意义。