Vxworks下策略路由研究及其原型实现

策略路由是嵌入式网络产品的一个重要功能,而Vxworks作为嵌入式开发的首选实时操作系统,没有实现这一功能。在分析了策略路由原理及Vxworks原IP协议栈数据转发机制的基础上,提出了加入策略路由后VxworksIP协议栈的数据转发机制,并实现了它的原型。     

策略路由的工作原理与具体网络应用

传统的路由策略都是使用从路由协议派生出来的路由表,根据目的地址进行报文的转发。在这种机制下,路由器只能根据报文的目的地址为用户提供比较单一的路由方式,它更多的是解决网络数据的转发问题,而不能提供有差别的服务。基于策略的路由为网络管理者提供了比传统路由协议对报文的转发和存储更强的控制能力。基于策略的路由比传统路由控制能力更强,使用更灵     

基于COPS的PIM-SM多播转发树切换策略的研究

该文对PIM-SM多播路由协议现有的多播转发树切换策略及其配置方式进行了较为全面的分析,针对其所存在的问题提出了基于COPS协议的PIM-SM多播转发树切换策略模型。该模型中引入了COPS协议的客户/服务器体系结构,从而实现了切换策略的集中管理与配置。同时,通过对多播转发树及其相关特性的深入研究,设计出两种具体的切换策略实例。在对该模型的模拟和测试中,对实验所获取的测试结果分析表明,基于COPS的切换策略模型具有较高的灵活性和适应性,所提出的两种切换策略可以有效地改善网络的整体性能和稳定性,达到了预期效果。     

一种基于左、右手法则的GPSR分区边界转发路由协议*

针对无线传感器网络贪婪地理路由协议中的路由空洞问题,分析了现有路由空洞解决策略的不足,对GPSR路由协议中边界转发策略进行改进,提出了一种左、右手法则相结合的分区边界转发策略.仿真结果表明,改进后的协议能够以较小的控制开销代价,提高数据包投递成功率,减少路由跳数,提高贪婪地理路由协议的实时性.     

一种采用按需路由策略的MPRN路由协议

提出了一种采用按需路由发现策略的移动分组无线网路由协议。协议采用按需路由发现过程,动态更新路由信息和建立路由转发组。数据包在转发组成员间进行有限泛洪,使协议能够降低对带宽的占用及减少可能的大量路由更新信息的传播。     

一种基于改进RTS/CTS的MANET高效报文转发策略

MANET网络由可自主移动的无线节点组成。节点的自主移动导致了链路路由的改变,因此需要有一个机制维护和发现路由信息。目前人们已经针对MANET网络提出了几种路由协议,但这些路由协议都是基于IP的且路由维护的代价高,这严重影响了MANET网络的稳定性、可扩展性和用户有效带宽。本文提出了一种基于改进RTS/CTS的MANET高效报文转发策略。该策略对标准IEEE 802.11协议进行了修改,利用改进的RTS/CTS报文信息,进行报文转发,从而避免了使用MANET网络路由协议给网络性能带来的影响。使用改进的NS-2模拟了基于改进RTS/CTS的MANET高效报文转发策略。模拟结果表明:该策略可以有效地降低路由维护的开销并降低报文传输的延迟。     

基于最优转发策略的无线传感器网络随机路由协议

提出一种基于地理信息的随机路由协议,该协议以优化参数选择候选路由节点.为确定候选路由节点数据转发的优先级,引入数据包传递期望值EPA.EPA综合考虑了链路质量以及数据包传递的距离,确定离目的节点越近的候选节点数据转发的优先级越高.经过理论分析,该转发策略能够使EPA取得最大值,是一种局部最优策略.仿真实验结果表明,该协议在数据传输延迟和数据吞吐率等方面明显优于地理路由协议.     

一种实现PIM-SM组播数据线速转发的方案

PIM-SM是目前应用最为广泛的域内组播路由协议,在通常的路由器中大都采用软件的方式实现,数据转发速度受到系统处理能力的限制难以进一步提高。提出了通过采用硬件方式实现组播数据线速转发的方法,并得到了满意的测试结果。     

协议无关的数据中心网络源路由机制研究

传统数据中心网络已经不能满足当前大规模网络和云计算架构的需求, 传统数据中心网络的路由策略会导致转发单元的臃肿; 同时当规模增大时传统网络中的拓扑管理策略也不再适用. 协议无感知转发技术是软件定义网络中转发平面的一种创新技术. 本文结合源路由和协议无感知转发技术, 提出两种数据中心网络的关键技术: 首先, 设计一种协议无关的源路由机制, 从而简化转发单元; 其次, 提出一种主机和控制器间协作的拓扑管理算法, 从而减少探测包的冗余. 最后, 本文在数据中心网络中实现了以上技术, 实验结果表明本文提出的源路由机制可以有效降低转发单元的流表规模, 拓扑管理策略可以极大地减少探测包的冗余.     

RIP和OSPF路由协议在Click软件路由器中的实现

Click是一种模块化的软件路由器体系结构,基于该体系结构用户可以根据自己的需求搭建不同功能的路由器.针对Click软件路由器支持静态路由协议的局限性,引入模块化路由器软件协议栈XORP(eXtensible Open Router Platform),实现了动态路由协议在Click软件路由器上的扩展.通过搭建实验网络拓扑环境,验证了基于Click转发平台的两种不同的动态路由协议RIP和OSPF,并进行了相关测试和性能分析.实验结果表明,Click软件路由器的转发性能与Linux内核基本一致,但相比较而言,Click软件路由器具有灵活、可扩展、模块化等不可比拟的优势.     

Universal Continuous Routing Strategies

We analyze universal routing protocols, that is, protocols that can be used for any communication pattern in any network, under a stochastic model of continuous message generation. In particular, we present two universal protocols, a store-and-forward and a wormhole routing protocol, and characterize their performance by the following three parameters: the maximum message generation rate for which the protocol is stable, the expected delay of a message from generation to service, and the time the protocol needs to recover from worst-case scenarios. Both protocols yield significant performance improvements over all previously known continuous routing protocols. In addition, we present adaptations of our protocols to continuous routing in node-symmetric networks, butterflies, and meshes. Received October 1996, and in final form April 1997.     

动态大型计算机网络的路由通信协议

本文了一种基于离散动态规划原理的分层动态路由协议（ＨＤＲＰ）它适应于分族拓扑的动态大型计算机网络（ＤＬＣＮ）文中给出了该协议路由信息更新的路由决策的实现过程，以及它的正确性证明和复杂性分析，通过仿真实验，研究了该协议的吞吐量和平均报文延迟等特性。文中 一种基于学习自动机的网络故障概率估计了方法及其路由策略，本文的研究表明，分层动态路由协议为动态大型计算机网络的路由决策提供了一种新的有效途径。     

Virtual-Force-Based Geometric Routing Protocol in MANETs

Routing is the foremost issue in mobile ad hoc networks (MANETs). To guarantee delivery and improve performance, most position-based routing protocols, e.g., greedy-face-greedy (GFG), forward a message in greedy routing mode until the message is forwarded to a local minimum where greedy forwarding is impossible. They then switch to a less efficient mode known as face routing. Face routing requires the underlying network to be a planar graph which makes geometric routing only theoretically feasible. To remove this constraint, this paper tackles the local minimum problem with two new methods. First, we construct a virtual small-world network by adding virtual long links to the network to reduce the number of local minima. Second, we use the virtual force method to recover from local minima without relying on face routing. Combining these two methods, we propose a purely greedy routing protocol, the small-world iterative navigation greedy (SWING+) routing protocol. Simulations are conducted to evaluate SWING+ against existing geometric routing protocols. Simulation results show that SWING+ guarantees delivery, and that its performance is comparable to that of the state-of-the-art greedy other adaptive face routing (GOAFR+) routing protocol.     

A Buffer Scheduling Method Based on Message Priority in Delay Tolerant Networks

Routing protocols in delay tolerant networks usually utilize multiple message copies to guarantee the message delivery, in order to overcome unpredictable node mobility and easily-interrupted connections. A store-carry-and-forward paradigm was also proposed to further improve the message delivery. However, excessive message copies lead to the shortage of buffer and bandwidth. The spray and wait routing protocol has been proposed to reduce the network overload caused by the buffer and transmission of unrestricted message copies. However, when a node’s buffer is quite constrained, there still exist congestion problems. In this paper, we propose a message scheduling and drop strategy on spray and wait routing protocol (SDSRP). To improve the delivery ratio, first of all, SDSRP calculates the priority of each message by evaluating the impact of both replicating and dropping a message copy on delivery ratio. Subsequently, scheduling and drop decisions are made according to the priority. In order to further increase delivery ratio, we propose an improved message scheduling and drop strategy on spray and wait routing protocol (ISDSRP) through enhancing the accuracy of estimating parameters. Finally, we conduct extensive simulations based on synthetic and real traces in ONE. The results show that compared with other buffer management strategies, ISDSRP and SDSRP achieve higher delivery ratio, similar average hopcounts, and lower overhead ratio.     

用WSE实现SOAP消息路由

SOAP是WebService的重要技术之一，它以XML形式提供了一个简单轻量的、用于在分散或分布环境中交换结构化和类型化信息的机制。但SOAP规范没有定义标准的路由协议，而只是提供了一个可扩展的框架。WSE为，NET框架开发人员提供了最新的Web服务功能，它支持数字签名、消息路由等。文章详细分析SOAP协议特点、SOAP消息框架、消息处理模型和SOAP的HTTP协议绑定，重点介绍并通过具体实验实现了用WSE进行SOAP消息路由的全过程。WSE为各种规范都提供了很好的支持，它将服务器端的WebMethods和客户端的代理巧妙地结合起来。     

There is no optimal routing policy for the torus

A routing policy is the method used to select a specific output channel for a message from among a number of acceptable output channels. An optimal routing policy is a policy that maximizes the probability of a message reaching its destination without delays. Optimal routing policies have been proposed for several regular networks, including the mesh and the hypercube. An open problem in interconnection network research has been the identification of an optimal routing policy for the torus. In this paper, we show that there is no optimal routing policy for the torus. Our result is demonstrated by presenting a detailed example in which the best choice of output channel is dependent on the probability of each channel being available. This result settles, in the negative, a conjecture by Wu concerning an optimal routing policy for the torus.     

映射服务器一致性测试例的设计与实现

一体化网络提出了接入路由标识、交换路由标识及其映射理论,解决了传统网络中的移动、安全等问题。映射服务器负责管理一体化网络中的各种标识及其映射关系,是一体化网络中的关键设备,需要较高的安全可靠性。映射服务器一致性测试是保证映射服务器按照协议描述安全有效可靠运行的重要测试方法。详细介绍了映射服务器一致性测试的实现环境与设计方案,详细描述了一致性测试几种测试例的消息格式设计,并对测试结果进行分析。     

时延容忍网络的蔓延路由协议的研究

蔓延路由广泛应用于时延容忍网络(DTNs)。然而,传统的蔓延路由存在资源消耗过多问题,如节点能耗和消息缓存空间。即使消息已传递到目的节点,消息可能仍停留于节点的缓存区,直至消息过期,这会增加能耗。为此,对节点缓存空间的释放时间进行研究,并提出基于释放时间预测的蔓延路由,其目的在于通过减少消息占用缓存的时间,降低资源开销。基于蔓延路由特性,建立基于常微分方程的消息传播模型,并预测消息到达目的节点的时间,再在确保消息被最多节点传染的前提下,推导从缓存区内删除消息的准确时间(释放时间)。实验数据表明,与传统的蔓延路由相比,采用预测释放时间的蔓延路由在维持同等路由性能的同时,降低了能耗和开销。     

Fine grained load balancing in multi-hop wireless networks

In this paper we address the problem of local balancing in multi-hop wireless networks. We introduce the notion of proactive routing: after a short pre-processing phase in which nodes build their routing tables by exchanging messages with neighbors, we require that nodes decide the relay of each message without any further interaction with other nodes. Besides delivering very low communication overhead, proactive routing protocols are robust against some well known active attacks to network routing. In this framework, we develop a proactive routing protocol that is able to balance the local load. Experiments show that our protocol improves network lifetime up to 98% and that it delivers a network that is more robust against attacks that have the goal of getting control over a large part of the network traffic.     

Reasonable routing in delay/disruption tolerant networks

Delay/disruption tolerant networking (DTN) is an approach to networking where intermittent connectivity exists: it is often afforded by a store and forward technique. Depending on the capability of intermediary nodes to carry and forward messages, messages can be eventually delivered to their destination by mobile nodes with an appropriate routing protocol. To have achieved a successful delivery, most DTN routing protocols use message duplication methods. Although messages are rapidly transferred to the destination, the redundancy in the number of message copies increases rapidly. This paper presents a new routing scheme based on a stochastic process for epidemic routing. Message redundancy is efficiently reduced and the number of message copies is controlled reasonably. During the contact process of nodes in the network, the number of message copies changes, and according to the variability in the number of copies, we construct a special Markov chain, birth and death process, on the number of message copies then calculate and obtain a stationary distribution of the birth and death process. Comparing the theoretical model with the simulation we have performed we see similar results. Our method improves on time-to-live (TTL) and antipacket methods, in both redundancy and delivery success efficiency.