基于MSTP协议的一致性测试设计

MSTP协议是针对STP收敛速度慢，RSTP不能进行基于802.1Q的流量分担等情况下提出的一种新的多域生成树协议。在扼要介绍此协议的实现原理的基础上，设计了针对此协议一致性的测试方法和测试组织，并应用于交换机的实际测试中，同时，给出了具体的测试实例，并对测试结果进行了分析。     

多生成树协议实现负载均衡实验的设计与实施

生成树协议能够解决环路带来的问题,提高网络的健壮性和稳定性。但是,简单地部署生成树协议并不能充分地利用链路资源,造成网络资源浪费。依据多生成树协议（MSTP）理论,设计了一种实验方案能同时实现链路冗余和负载均衡,提高网络整体性能。     

An optimization framework for the energy management of carrier ethernet networks with Multiple Spanning Trees

We propose an energy management framework to optimize the energy consumption of networks using the Multiple Spanning Tree Protocol such as Carrier Grade Ethernet networks. The objective is to minimize the energy consumption of nodes and links while considering QoS constraints. The energy management is done through the Multiple Spanning Tree Protocol (MSTP) by choosing from a given set the most appropriate Spanning Trees and the most appropriate edges to operate while respecting the traffic demands. A trade-off framework between energy consumption and network performance is proposed. Results show that it is possible to achieve a good traffic engineering while operating the network closer to the minimum energy value.     

生成树协议(STP)在计算机网络中的应用

生成树算法的网桥协议STP(Spanning Tree Protocol)它通过自动形成生成树使得在网络中一个透明的网桥以动态方式在复杂的网络拓扑结构中沿环状工作。网络中的环路由网桥之间通过交换配置桥协议数据单元消息来进行监测,通过关闭选择的网桥接口的方式破除环路。局域网通常由多种网络设备相互连接形成,我们只有消除网络中的环路才能有效降低广播风暴的发生,也就是说网络中的链路应组成树形的无环路结构,使用STP(生成树协议)就可以解决这样的问题。     

基于STP协议的物理网络拓扑发现算法

拓扑发现是网络管理的重要基础。该文提出一种基于网桥生成树协议STP的算法,利用简单网络管理协议(SNMP)获得各个交换机MIB库中的生成树状态信息,根据生成树协议推导出网络的物理拓扑。和已有方法相比,该算法不要求各个网桥FDB表的信息是完备的,同时也能很好地发现备份链路和集线器、哑交换机等不支持SNMP的设备。实验表明该算法是一个准确、全面的拓扑发现算法。     

以太环网的路径保护和恢复算法的研究和实现

作为局域网主要组网技术的以太网，由于缺乏完善的OAM机制，无法提供小于50ms的路径保护和故障恢复机制，不能用于城域的环形传送网络中．本文提出了一种用于以太环网（Ethernet Ring）上的轻量级的分布式路径保护和恢复算法．该算法不同于现有的生成树算法和以太网保护技术，能够在小于50ms内实现保护倒换且避免环路，具有较好的可扩展性且开销较小．最后，文章介绍了该算法在一个基于网络处理器的路由交换系统上的具体实现．     

ABridges: Scalable,self-configuring Ethernet campus networks

This article describes a scalable, self-configuring architecture for campus networks, the ABridges architecture. It is a two-tiered hierarchy of layer two switches in which network islands running independent rapid spanning tree protocols communicate through a core formed by island root bridges (ABridges). ABridges use AMSTP, a simplified and self configuring version of MSTP protocol, to establish shortest paths in the core using multiple spanning tree instances, one instance rooted at each core edge ABridge. The architecture is very efficient in terms of network usage and path length due to the ability of AMSTP to provide optimum paths in the core mesh, while RSTP is used to aggregate efficiently the traffic at islands networks, where sparsely connected, tree-like topologies are frequent and recommended. Convergence speed is as fast as existing Rapid Spanning Tree and Multiple Spanning Tree Protocols.     

Lifetime maximizing dynamic energy efficient routing protocol for multi hop wireless networks

Energy efficiency is recognized as a critical problem in wireless networks. Many routing schemes have been proposed for finding energy efficient routing paths with a view to extend lifetime of the networks – however it has been observed that the energy efficient path depletes quickly. Further, an unbalanced distribution of energy among the nodes may cause early death of nodes as well as network. Hence, balancing the energy distribution is a challenging area of research in wireless networks. In this paper we propose an energy efficient scheme that considers the node cost of nodes for relaying the data packets to the sink. The node cost considers both the remaining energy of the node as well as energy efficiency. Using this parameter, an energy efficient routing algorithm is proposed which balances the data traffic among the nodes and also prolongs the network lifetime. Simulation shows that proposed routing scheme improves energy efficiency and network lifetime than widely used methods viz., Shortest Path Tree (SPT) and Minimum Spanning Tree (MST) based PEDAP, Distributed Energy Balanced Routing (DEBR) and Shortest Path Aggregation Tree Based Routing Protocol.     

基于VLAN的生成树协议仿真

应用Boson Netsim仿真软件,提出交换机上基于VLAN划分生成树的虚拟通信方案。介绍了生成树协议STP的工作原理和技术要点,设计了模拟拓扑结构图,分析了VLAN和STP的配置命令。使用虚拟主机对通信网络进行了仿真测试,结果表明STP的配置是有效的。     

千兆以太网路由算法研究

千兆以太网中使用生成树协议来保证网络中不出现逻辑环路。但网络拓扑的生成树结构严重制约了千兆以太网的性能和可扩展性。本文提出无须完全阻塞产生循环的端口,只要禁止特定的拐弯集合,即可避免逻辑环路,并具体应用拐弯模型,设计了一种适合于千兆以太网的路由算法TR。模拟实验证明使用TR路由算法较之使用生成树算法而言网络性能有了明显的提高。     

Spanning tree elevation protocol: Enhancing metro Ethernet performance and QoS

The economics and familiarity of Ethernet technology is motivating the vision of wide-scale adoption of Metro Ethernet Networks (MEN). Despite the progress made by the community on additional Ethernet standardization and commercialization of the first generation of MEN, the fundamental technology does not meet the expectations that carriers have traditionally held in terms of network resiliency, load management, and Quality of Service (QoS). We propose a new concept of Spanning Tree Elevation Protocol (STEP) that increases MEN performance while supporting QoS including traffic policing and service differentiation. STEP manages multiple Spanning Trees as a means to control the traffic flow rates and to differentiate classes of traffic. Whenever a service level agreement is compromised, STEP redirects frames of affected flows to the next spanning tree in sequence utilizing the alternate paths. As a result, the capacity in terms of network throughput is greatly enhanced while almost avoiding any reconvergence time in the case of failures. The gain ranges from 1.7% to 7.3% of the total traffic in the face of failure; while load balancing increases an additional 12.8% to 37% of the total throughput. At the same time, STEP maintains the required bandwidth for high priority traffic class during the failure scenarios and the high congestion scenarios.     

一种交换式以太网拓扑结构的发现算法

首先介绍了目前局域网拓扑发现的主要方法及存在的问题,然后提出一个基于生成树协议 地址转发表的交换式以太网物理拓扑结构的自动发现算法.算法首先利用生成树协议建立起交换机之间的连接关系,在此基础上进一步利用地址转发表建立起交换机与主机的连接关系.该算法 1)能给发现被生成树协议阻塞的连接;2)通过处理连接冲突,能够准确无误的发现网络物理拓扑结构;3)算法开销小,时间复杂度低.文中算法已成功地应用于社区宽带综合业务网络管理系统(CBISNMS)中.     

生成树协议的研究和实现

生成树协议因为能在局域网中构建无环路的逻辑拓扑结构和提供较强的网络容错功能,而在局域网的可靠性设计中得到广泛应用。论文简要介绍了局域网可靠性设计的思想和生成树协议的工作原理,重点描述了STP在交换机中的实现。     

基于欧氏最小生成树的无线Ad Hoc网络容量研究

无线Adhoc网络容量是当前的一个研究热点。在Gupta和Kumar提出的协议模型和物理模型基础上,推导了无线Adhoc网络基于欧氏最小生成树的单播、多播容量,且指出当多播组尺寸小于总的网络节点数时,多播容量比单播容量大。基于NS-2的仿真实验验证了多播容量上限是有效的。     

On exact solutions for the Minmax Regret Spanning Tree problem

The Minmax Regret Spanning Tree problem is studied in this paper. This is a generalization of the well-known Minimum Spanning Tree problem, which considers uncertainty in the cost function. Particularly, it is assumed that the cost parameter associated with each edge is an interval whose lower and upper limits are known, and the Minmax Regret is the optimization criterion. The Minmax Regret Spanning Tree problem is an NP-Hard optimization problem for which exact and heuristic approaches have been proposed. Several exact algorithms are proposed and computationally compared with the most effective approaches of the literature. It is shown that a proposed branch-and-cut approach outperforms the previous approaches when considering several classes of instances from the literature.     

交换机生成树环路的生成及防治

针对企业网的特点,通常都会使用冗余技术增强其架构及提高运行可持续性,但是冗余技术应用在交换网络中时由于环路的作用会产生帧重复、广播风暴及不稳定的MAC地址等问题致使网络瘫痪.本文旨在说明交换机生成树环路的生成以及如何实现冗余链路的控制工作即生成树协议的工作实现从而防止环路的危害.     

最多叶子生成树问题的核化算法

对算法领域的最多叶子生成树问题进行了深入研究,提出了对简单连通图2度节点的化简规则,并证明了不含2度节点的图的生成树的叶子节点数的下限为(N+6)/4,给出了构造这样一棵生成树的构造性方法.基于上述化简规则和所证明的结论,给出了最多叶子生成树问题的核化算法,该核化算法可以在O(n2)时间内得到一个4k-6大小的线性核.对于这样一个较小的核,将大大提高相关的参数算法和近似算法的性能.     

Shortcut Switching Strategy in Metro Ethernet networks

IEEE Spanning Tree Protocol (STP) is a layer-2 protocol which provides a loop-free connectivity across various network nodes. STP does this task by reducing the topology of a switched network to a tree topology where redundant ports are blocked. Blocked ports are then kept in a standby mode of operation until a network failure occurs. In STP, there is not any traffic engineering mechanism for load balancing. This results in uneven load distribution and bottlenecks especially close to the Root. This protocol imposes a severe penalty on the performance and scalability of Metro Ethernet networks, since it makes inefficient use of links and switches. In this paper, we propose a novel switching strategy named Shortcut Switching Strategy (SSS) that uses blocked ports to forward frames in some special and restricted cases. It is an improved version of the standard STP and its main advantages are simplicity and backward-compatibility. Shortcut Switching Strategy decreases the average traffic volume on links and switches, improves load balancing on links and switches and reduces the Bandwidth Blocking Probability. We will demonstrate these improvements by using analytical and simulation methods for some well-known topologies. Simulation results show that using SSS can give about 25% reduction in average link loads, average switch loads and average number of hop counts compared to STP.     

桥接局域网第2层拓扑结构的自动发现

With the rapid development and the wide use of Bridged Local Area Networks, the importance of below-OSI-Layer-3 topology comes to be realized. Recent research work has demonstrated that active layer-2 topology can be determined using Address Forwarding Information. The large quantities of address forwarding entries in a typical BLAN, however, make their algorithms both time-consuming and bandwidth-consuming. In view of the above and the fact that transparent bridges are used preponderantly in real networks, we base our algorithm on information supported by Spanning Tree Protocol M1B group, which reduces the cost of acquiring and processing information, and improves the accuracy. Our algorithm relies on standard MIB information and can be used in heterogeneous environments     

基于网页可达性和访问率的电子超市网站链接结构优化方法

定义了链接可达性和网页可达性的概念．为计算网页可达性，设计了计算到达网页路 径的路径树生成算法(PTSA)．建立了一种极大化网页访问率与可达性之间相关性的网站链接 结构调整的数学模型，并提出将PTSA嵌入禁忌搜索的求解方法．试验结果表明本文的方法可 以帮助网站设计者改进网站的链接结构．