Modeling path duration distributions in MANETs and their impact on reactive routing protocols

We develop a detailed approach to study how mobility impacts the performance of reactive mobile ad hoc network routing protocols. In particular, we examine how the statistics of path durations including probability density functions vary with the parameters such as the mobility model, relative speed, number of hops, and radio range. We find that at low speeds, certain mobility models may induce multimodal distributions that reflect the characteristics of the spatial map, mobility constraints and the communicating traffic pattern. However, this paper suggests that at moderate and high velocities the exponential distribution with appropriate parameterizations is a good approximation of the path duration distribution for a range of mobility models. Analytically, we show that the reciprocal of the average path duration has a strong linear relationship with the throughput and overhead of dynamic source routing (DSR), which is also confirmed by simulation results. In addition, we show how the mathematical expression obtained for the path duration distribution can also be used to prove that the nonpropagating cache hit ratio in DSR is independent of velocity for the freeway mobility model. These two case studies illustrate how various aspects of protocol performance can be analyzed with respect to a number of significant parameters including the statistics of link and path durations.     

Performance comparison of trust-based reactive routing protocols

Ad hoc networks, due to their improvised nature, are frequently established in insecure environments and hence become susceptible to attacks. These attacks are launched by participating malicious nodes against different network services. Routing protocols, which act as the binding force in these networks, are a common target of these nodes. A number of secure routing protocols have recently been proposed, which make use of cryptographic algorithms to secure the routes. However, in doing so, these protocols entail a number of prerequisites during both the network establishment and operation phases. In contrast, trust-based routing protocols locate trusted rather than secure routes in the network by observing the sincerity in participation by other nodes. These protocols thus permit rapid deployment along with a dynamically adaptive operation, which conforms with the current network situation. In this paper, we evaluate the performance of three trust-based reactive routing protocols in a network with varying number of malicious nodes. With the help of exhaustive simulations, we demonstrate that the performance of the three protocols varies significantly even under similar attack, traffic, and mobility conditions. However, each trust-based routing protocol has its own peculiar advantage making it suitable for application in a particular extemporized environment.     

一种基于实时车流密度信息的VANET路由协议

在车载自组网中,路由协议很大程度上决定了整个网络的性能。如何有效的利用车流信息提高传输质量是改善路由性能的一个关键问题。本文基于速度-密度线性模型,提出了一种实时车流密度的路由协议RVDR(Real-time Vehicle Density Routing)。该协议通过与邻居节点交换的速度信息,对相关道路车流密度进行预测,并给出基于车流密度信息的路径选择方法。仿真结果表明,与现有协议相比,RVDR协议在实时性和高效性等性能方面得到改进。     

On efficient traffic engineering with DV-based routing protocols in DiffServ-aware IP networks

In this paper, an approach to efficient traffic engineering in the DiffServ-aware network environment is proposed. We focus to distance vector-based routing protocols, considering both modifications of routing protocols needed to support path differentiation and traffic engineering methods relied on adjusting multiple per-link costs to particular network conditions. Further, a method for determining link cost of particular traffic class, as a unique generic function of the single generalized performance metric has been proposed. In order to achieve efficient traffic engineering, possible approximations of generic cost function and mappings of generalized to particular metrics have been proposed. Finally, prerequisites for implementing proposed approach have been discussed in the context of different administrative policies and time scales of their application.     

Applying trust enhancements to reactive routing protocols in mobile ad hoc networks

Due to the characteristics of mobile ad hoc networks, such networks are more susceptible to the destruction of malicious attacks or denial of cooperation. It would be easy for an adversary or a malicious node to launch attacks on routing function, especially attacks on packet routing. In order to mitigate these hazards, we incorporate the concept of ‘trust’ into MANETs, and abstract a decentralized trust inference model. The core of this model is trust computation, which is divided into two parts: historical trust assessment and trust prediction. We can quantify a node’s historical trust based on its historical behaviors via introducing multiple trust attributes. The fuzzy AHP method based on entropy weights is used to calculate the weight of trust attributes. By making use of the obtained historical trust data sequence, we propose an improved dynamic grey-Markov chain prediction measure to effectively estimate node’s trust prediction. In order to verify the validity of our trust model, we propose a trust-enhanced unicast routing protocol and a trust-enhanced multicast routing protocol, respectively. Both of the two new protocols can provide a feasible approach to kick out the untrustworthy nodes and choose the optimal trusted routing path. Moreover, the new proposed data-driven route maintenance mechanisms can reduce the routing overhead. The persuasive experiments have been conducted to evaluate the effectiveness of the new proposed trust-enhanced routing protocols in the aspects of packets delivery ratio, end-to-end latency, malicious node detection and attack resistance.     

VANET中路由协议分析

分析目前大多数VANET路由算法,将其归类为基于位置的贪婪路由算法、基于锚节点路由算法、基于街道集路由算法和基于簇路由算法,并着重于这些特点设计每类算法,通过NS2仿真实验对比和分析,为进一步的研究提出新的课题。     

ASON的路由协议探讨

宽带业务对网络的传输性能提出了更高的要求,尤其是最近掀起的宽带接入高潮,使得传输网建设处于通信网络建设的风头浪尖。然而,传统的“带宽驱动型”运营模式使运营商无法灵活地调配网络资源,传输投资重复性较高,带宽利用率极低。面向智能光网络的“用户驱动型”运营模式,借助路由选择协议和信令机制,使点对点的光网络变得灵活起来,进一步提高带宽的使用率和多业务承载能力,使运营商能够关注用户需求和投资回报,从而实现可持续盈利的良性循环。ASON的出现智能光网(ION)的概念很早就被IETF提上了议事日程,但由于一直没有公认的标准,各厂…     

Implications of physical layer overhead on the design ofmultiaccess protocols

The authors examine the implications of physical layer overhead on the design of multiaccess protocols under a demand-assignment framework, comparing full-slot contention with mini-slot contention. Even if the physical layer overhead is substantial relative to the packet size, we show that after `paying the price' of transmitting the physical layer overhead it is still better, from a delay-throughput perspective, to only transmit a short request rather than a full packet during a contention period     

Performance of new link state advertisement mechanisms in routing protocols with traffic engineering extensions

The prevalent use of best-effort topology driven IP routing protocols with shortest path calculations can often lead to serious imbalance of packet traffic distribution when least cost paths converge on the same set of links, leading to unacceptable delays or packet loss even in the presence of feasible paths over less utilized links. Recently proposed enhancements to common routing protocols are promising to overcome such shortcomings by providing the means to distribute link state information that is more pertinent to traffic engineering in routed networks. This article presents several key results on the performance of the recently proposed OSPF-TE, with particular emphasis on OSPF-TE protocol traffic overhead and the impact of new link state advertisement triggering mechanisms on traffic-engineered routing accuracy.     

Performance evaluation of routing protocols for MANETs with known connectivity patterns using evolving graphs

The assessment of routing protocols for mobile wireless networks is a difficult task, because of the networks’ dynamic behavior and the absence of benchmarks. However, some of these networks, such as intermittent wireless sensors networks, periodic or cyclic networks, and some delay tolerant networks (DTNs), have more predictable dynamics, as the temporal variations in the network topology can be considered as deterministic, which may make them easier to study. Recently, a graph theoretic model—the evolving graphs—was proposed to help capture the dynamic behavior of such networks, in view of the construction of least cost routing and other algorithms. The algorithms and insights obtained through this model are theoretically very efficient and intriguing. However, there is no study about the use of such theoretical results into practical situations. Therefore, the objective of our work is to analyze the applicability of the evolving graph theory in the construction of efficient routing protocols in realistic scenarios. In this paper, we use the NS2 network simulator to first implement an evolving graph based routing protocol, and then to use it as a benchmark when comparing the four major ad hoc routing protocols (AODV, DSR, OLSR and DSDV). Interestingly, our experiments show that evolving graphs have the potential to be an effective and powerful tool in the development and analysis of algorithms for dynamic networks, with predictable dynamics at least. In order to make this model widely applicable, however, some practical issues still have to be addressed and incorporated into the model, like adaptive algorithms. We also discuss such issues in this paper, as a result of our experience.     

基于博弈论的无线自组网路由协议研究

Ad hoc网络,是无线自组织网络的简称.它没有固定的基础设施,网路中的每个节点具有双重身份,即通信终端和路由器.路由协议是Ad hoc网络的关键技术,但传统的协议在设计时并未考虑效率因素.本文基于博弈论提出一种平均场均衡的方法,能有效的减少信息泛洪,以满足节点移动性对自组网的性能要求.     

A survey of geocast routing protocols

Geocasting is the delivery of a message to nodes within a geographical region. With geocast, new services and applications are feasible, such as finding friends who are nearby, geographic advertising, and accident or wrong-way driver warning on a motorway. In this article we present a survey on geocast routing protocols. The protocols mainly differ in whether they are based on flooding, directed flooding, or on routing without flooding, and whether they are suitable for ad hoc networks or for infrastructure networks. Based on these criteria we propose a classification of geocast protocols. Our protocol comparison includes message and memory complexity, robustness, and the ability to deliver geocast packets in partially partitioned networks. Finally, we present simulations to compare the approaches based on flooding, directed flooding, and routing without flooding.     

The viewserver hierarchy for interdomain routing: protocols andevaluation

We present an interdomain routing protocol based on a new hierarchy, referred to as the viewserver hierarchy. The protocol satisfies policy and type of service (ToS) constraints, adapts to dynamic topology changes including failures that partition domains, and scales well to a large number of domains without losing detail (unlike the usual scaling technique of aggregating domains into superdomains). Domain-level views are maintained by special nodes called viewservers. Each viewserver maintains a view of a surrounding precinct. Viewservers are organized hierarchically. To obtain domain-level source routes, the views of one or more viewservers are merged (up to a maximum of twice the levels in the hierarchy). We also present a model for evaluating interdomain routing protocols, and apply this model to compare our viewserver hierarchy against the simple approach where each node maintains a domain-level view of the entire internetwork. Our results indicate that the viewserver hierarchy finds many short valid paths and reduces the amount of memory requirement by two orders of magnitude     

A study of encoding overhead in network management protocols

Next‐Generation Network (NGN) is a critical scenario in terms of network management because of its network dimension, its number of users and its heterogeneity. Since the introduction of the Simple Network Management Protocol (SNMP) at the beginning of the 1990s, much effort has been devoted to the development of new network management technologies. Both the Desktop Management Task Force (DMTF) and the Internet Engineering Task Force (IETF) have developed different network and system management protocols, such as Common Open Policy Service, Web‐Based Enterprise Management, Network Configuration and even adapted other protocols, such as Diameter and Web Services. A network management technology with poor scalability could compromise NGN management and ultimately NGN network behaviour. This paper analyses the network overhead of several management technologies developed by the DMTF and IETF, and goes on to compare their results with the usage of SNMP. Furthermore, some deployment recommendations are proposed for performance optimization in NGNs. Copyright © 2012 John Wiley & Sons, Ltd.     

移动Ad hoc路由协议中的节点预测研究

在移动Ad hoc网络中,节点是随意移动的,为确定某一时刻的网络拓扑,必须首先探测出网络中所有节点的位置和移动特征,这样也能避免Ad hoc网络频繁出现链路故障。为此,提出一种继承自AOMDV协议的增加节点预测的新型路由协议NP-AOMDV,并与AOMDV在吞吐量、端到端时延、路由控制开销等做性能对比,通过NS2下的仿真结果分析可知,NP-AOM-DV比AOMDV性能有了一定的提高。     

AODV routing overhead analysis based on link failure probability in MANET

This article puts forward an Ad-hoc on-demand distance vector routing(AODV)routing overhead analysis method in mobile Ad-hoc network(MANET).Although multiple routing protocols have been proposed to improve the performance,scarcely any paper analyzed the routing overhead caused by routing setup and maintenance processes in mathematical way.Routing overhead consumes part of network resources and limits the supported traffic in the network.For on-demand routing protocols like AODV,the routing overhead depends on the link failure probability to a great extent.This article analyzes the collision probability caused by hidden-node problem and the impact on link failure probability.In chain and rectangle scenarios,it presents a mathematical analysis of the theoretical routing overhead of AODV protocol based on link failure probability.Simulations on OPNET 14.5platform match well with the theoretical derivation which confirms the effectiveness of the analysis method.     

A survey on routing protocols for wireless sensor networks

Recent advances in wireless sensor networks have led to many new protocols specifically designed for sensor networks where energy awareness is an essential consideration. Most of the attention, however, has been given to the routing protocols since they might differ depending on the application and network architecture. This paper surveys recent routing protocols for sensor networks and presents a classification for the various approaches pursued. The three main categories explored in this paper are data-centric, hierarchical and location-based. Each routing protocol is described and discussed under the appropriate category. Moreover, protocols using contemporary methodologies such as network flow and quality of service modeling are also discussed. The paper concludes with open research issues.     

基于流量工程的自动交换光网络新路由协议研究

为了研究基于流量工程的自动交换光网络(ASON)路由协议,采用基于源标签交换路由(LSR)路由泛供、仅广播链路可用带宽的增减的方法,得到了该协议能使LSR根据准确的带宽信息和波长可用信息选择路由的结果.结果表明,当链路中每个节点信息负荷量较小时,该协议拥有最小的链路阻塞率;与传统的路由机制相比,它能减少4～7倍的控制开销.     

流量工程中静态路由算法的研究

该文提出了一种应用于流量工程环境中的静态路由算法。考虑当前的网络资源情况,分优先级别在网络中计算并配置标记交换路径(Label Switched Path,LSP),当某一优先级有多条 LSP需要并行配置时,利用遗传算法搜索最优或较优的配置方案,使得网络的链路带宽使用率低于管理员定义的某个限定值,达到合理分布资源的目的。此外,提出了一种改进的 Dijkstra 算法计算 LSP的最短路径。