Reorder notifying TCP (RN‐TCP) with explicit packet drop notification (EPDN)

Numerous studies have shown that packet reordering is common, especially in networks where there is high degree of parallelism and different link speeds. Reordering of packets decrease the TCP performance of a network, mainly because it leads to overestimation of the congestion in the network. In this paper, we analyse the performance of networks when reordering of packets occur. We propose a proactive solution that could significantly improve the performance of the network when reordering of packets occurs. We report results of our simulation experiments, which support this claim. Our solution is based on enabling the senders to distinguish between dropped packets and reordered packets. Copyright © 2005 John Wiley & Sons, Ltd.     

A network processor‐based architecture for multi‐gigabit traffic analysis

The wide availability of cheap and effective commodity PC hardware has driven the development of versatile traffic monitoring software such as protocol analyzers, traffic characterizers and intrusion detection systems. Most of them are designed to run on general purpose architectures and are based on the well‐known libpcap API, which has rapidly become a de facto standard. Although many improvements have been applied to packet capturing software, it still suffers from several performance flaws, mainly due to the underlying hardware bottlenecks. To overcome these issues, this paper proposes a system architecture, which combines the high performance of a Network Processor card with the flexibility of software‐based solutions. It allows for removing most part of the hardware limitations exhibited by a purely PC‐based architecture, while preserving the full compliance to any software applications based on libpcap. In addition, the proposed system enables the use of monitoring applications at the wire speed, with the possibility of on‐the‐fly data processing. The system performance has been thoroughly assessed: the results show that it clearly outperforms the previous PC‐based solutions in terms of packet capturing power, while the timestamping accuracy is as good as that achieved by DAG cards. Copyright © 2009 John Wiley & Sons, Ltd.     

基于Internet的网络监控信息系统

本系统是基于民航导航设备开发的，集数据采集、远程控制、视频监控、网络信息发布于一体的网络监控系统。本文从软、硬件的角度详细介绍了系统的方案设计。该系统能够及时准确地采集现场导航设备的实时数据并进行相应的数据处理，具有可靠性、准确性高，易于维护性等特点。     

报文检测与发送相关算法设计

目前存在的网络监测软件基本都只是对捕获的数据包按标准的网络协议进行解析。然而,当数据包种类非常多时,数据捕获的可靠性很难保证,很多时候需要对自定义报文解析并进行仲裁。本算法主要以UDP协议报文数据段为重点,支持点对点、组播报文和广播报文的捕获与解析,既能按用户设计的应用层协议解析报文,又能高效地进行解析和仲裁。报文类型可由系统用户自行定义,用户可以根据需要添加报文规则,用于监控与分析报文。     

Topology-assisted deterministic packet marking for IP traceback

A novel deterministic packet marking (DPM) for IP traceback against denial of service (DoS) and distributed denial of service (DDoS) attacks is presented, which features good scalability and high accuracy. In this scheme, an ingress router pre-calculates a Hash of its IP address and splits the Hash into several fragments. When marking a packet, the router randomly selects a fragment to mark into the packet. In the traceback stage the victim identifies the marked router with the help of the map of its upstream routers. Based on the map, the victim can identify a candidate ingress router after receiving only several marked packets. The scheme overcomes defects in previous deterministic packet marking schemes, where too much packets are required to recover a router and high false positive rate occurs in case of large-scale DDoS. Theoretical analysis, the pseudo code and experimental results are provided. The scheme is proved to be accurate and efficient and can handle large-scale DDoS attacks.     

多目标控制系统中TCP粘包问题的解决方法

测控设备采用传输控制协议/网际协议(TCP/IP)作为基础协议,进行遥控多通道并行工作时易造成网络数据粘包.针对此问题,在对TCP协议特点进行分析的基础上,通过讨论TCP编程模型和流交付模型,研究了发生TCP数据流粘包时的网络数据特征,并分析了发生网络粘包的原因,提出了局域网环境下采用短连接、发送端及格式数据组包3种解决网络粘包的方法.实际测试结果证明了这3种方法的适应性及格式数据方法还原TCP网络数据包的有效性,可为基于TCP应用软件开发提供借鉴.     

IP网络传输话音和TDM业务的新技术-TDMoIP

介绍3TDMoIP的实现过程，主要对Ingress方向的上数据处理过程进行描述，在IP网络上实现数据处理业务。与传统网络相比，IP网络组网更简单经济，传送数据、图像、声音质量更好，与VOIP相比时延更小。     

Considerations for application‐layer multipath transport control

Multipath transport faces a lot of challenges caused by path diversity, network dynamics, and service diversity. An effective end‐to‐end multipath transport control mechanism becomes essential to efficiently utilize multiple paths. On the base of the general framework of multipath transport system based on application‐level relay proposed in our previous work, this paper presents a multipath transport control mechanism supporting various applications with different transmission requirements. We propose a multipath transport protocol suite, which is extensible and suitable for various applications, and a multipath transport control model in which an application‐dependent splitting granularity named flow block is introduced. Two load distribution models are explored: the earliest idle path first load distribution for reliable data transmission to maximize the data throughput and the packet reordering‐controlled load distribution for real‐time data transmission to minimize the packet reordering thereby reducing end‐to‐end delay and packet loss rate of multipath transport. Simulation results show that the proposed models can effectively improve data throughput for applications with reliable transmission requirements and reduce the total packet loss rate of the destination for applications with real‐time transmission requirements.     

网络隔离GAP技术之专用协议设计与实现

种类繁多的传统网络安全技术已无法满足网络安全的新需求,在此形势下,新的网络安全技术应运而生,主要是入侵检测技术和网络隔离技术.尤其是网络隔离GAP技术,已逐渐成为网络安全研究最活跃的领域,文中详尽分析了TCP/IP协议及分解,提出了流量控制模型,设计了专用协议,并利用Linux系统平台上的CAPI library实现了专用协议,不但提高了数据交换速度,而且改善了系统的安全性能,对GAP技术研究具有一定的参考与实用价值.     

一种基于负载选择的光分组交换缓存结构

提出了一种基于业务负载选择的光分组交换(OPS)网络的光缓存结构,根据业务负载大小灵活选择缓存方式。输出缓存光纤延迟线(FDL)采用分段式共享机制配置,输出/反馈共享缓存模块采用简并式配置,以提高有限数目FDL的利用率。分析和仿真表明,这种可选择的缓存结构可以有效降低丢包率和OPS节点需求的FDL数目。     

一种基于TCP／IP协议的网络协议安全系统设计

本文提出了基于包加密和防火墙技术在互联网上建立一个风络协议安全系统的新方法，并提出了开放安全结构和安全内部网的概念。     

IP网络性能指标体系的研究

网络性能指标是网络测评的基础。本文从网络测评的不同角度对IP网络的性能指标进行了综合分析，指出了一种能系统反映IP网络性能的指标体系，并给出了IP网络性能指标体系的形式描述。在此基础上引入了泛化指标和确定性指标的概念，探讨了确定性指标的内容有及描述框架。该研究突破了目前IP网络性能指标体系研究的简单性、局限性，对IP网络测试和性能评价具有指导意义。     

非时隙CDMA分组网络吞吐量性能分析:统一的方法

CDMA分组网络性能主要受限于信道中同时传输的其它分组的干扰.与时隙CDMA分组网络相比,非时隙CDMA分组网络所受到的干扰情况更加复杂.本文提出了一种非时隙CDMA分组网络的干扰分析模型,并采用递归方式建立了网络吞吐量性能分析的统一方法.在此基础上,分析了网络节点突发固定长度分组和突发可变长度分组两种情况下的网络吞吐量性能,并讨论了扩频增益和分组传输方式对网络性能的影响,给出了相应的数值结果.文章最后进一步讨论了吞吐量的上下界问题.与前人提出的马尔可夫模型相比,采用本文提出的方法可以得到更为准确的吞吐量性能.     

适应卫星IP网络的安全解决方案研究

卫星IP网络作为地面IP网络的延伸,其固有的信道特性带来了TCP性能问题和安全问题。目前业界提出的主流安全解决方案不能很好地适应TCP性能增强技术。文中通过对主流安全解决方案和TCP性能增强技术进行深入研究,挖掘二者不能良好适应的原因,最后提出一种新的适应卫星IP网络的安全解决方案。     

分组核心网分析系统功能与应周

随着移动通信业务的发展,高速移动数据业务成为各运营商业务发展的新重点和利润增长点。为了改善网络的性能和运维的效率,增强数据业务的盈利能力,采用分组核心网分析系统对分组核心网进行有效管控。结合应用实例,对相关功能进行了详细说明。通过实践应用证明,系统以其自身的特点发现并处理解决网络中存在的问题,是精细化作业工作的重要支撑手段。     

一种主动式移动IP包过滤设计方案

针对现阶段路由器难以同时支持移动IP通信和安全保障的问题，提出一种基于主动网络技术的主动式移动IP包过滤方案，解决了反向隧道技术中“移动节点-家乡代理-通信对端”存在的“反向三角路由”问题．实验表明，此方案在对路由器的软件和硬件稍作改动的前提下，较好地支持了移动IP通信，提高了分组路由的有效性．     

End‐to‐end delay and packet drop rate performance for a wireless sensor network with a cluster‐tree topology

In this paper, we study the delay performance in a wireless sensor network (WSN) with a cluster‐tree topology. The end‐to‐end delay in such a network can be strongly dependent on the relative location between the sensors and the sink and the resource allocations of the cluster heads (CHs). For real‐time traffic, packets transmitted with excessive delay are dropped. Given the timeline allocations of each CH for local and inter‐cluster traffic transmissions, an analytical model is developed to find the distribution of the end‐to‐end transmission delay for packets originated from different clusters. Based on this result, the packet drop rate is derived. A heuristic scheme is then proposed to jointly find the timeline allocations of all the CHs in a WSN in order to achieve the minimum and balanced packet drop rate for traffic originated from different levels of the cluster tree. Simulation results are shown to verify the analysis and to demonstrate the effectiveness of the proposed CH timeline allocation scheme. Copyright © 2012 John Wiley & Sons, Ltd.     

网络流量分析中的频繁项监测技术研究

无限数据流中频繁项监测问题定义为对给定输入数据流在任意时刻输出一个当前所有输入数据项中出现频率超过闽值的频繁数据类型及频率值的列表，它对于大规模网络流量分析具有重要意义。本文基于网络报文流分析的应用需求，归纳出一般意义上的报文流分析模型和频繁项监测问题抽象定义，并据此对当前典型的频繁项监测算法进行分析比较。本文还提出一种在有界存储中进行频繁项监测的高精度改进算法，实验结果表明该改进算法满足高速网络报文流的应用需求。     

TCP/IP协议的拥塞控制策略

网络拥塞问题会导致网络性能下降,对网络正常运行有很大影响,严重时会导致死锁的产生.文中分析了网络拥塞的产生的原因,并着重讨论了传统端到端的TCP拥塞控制的策略和方法,传统TCP拥塞控制策略提出了改进策略和网络层的IP拥塞控制策略.最后对基于TCP和IP拥塞控制策略进行了对比探讨.     

基于IP突发信源模型数据包的定量计算研究

本文以IP突发信源on/off模型的单IP业务源的数据包生成特性分析为基础,以队列缓冲配置和IP数据包丢失率、排队时延的计算为主要研究对象,通过对多业务源排队系统的IP数据包排队时延进行深入的综合分析,得出了一些新的QoS定量计算解析式,这些解析式可用于计算IP交换路由器QoS参数.