共查询到18条相似文献,搜索用时 179 毫秒
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基于GPS的端到端时延测量方法设计方案 总被引:1,自引:0,他引:1
端到端时延是评估Internet的网络性能的重要参数之一,也是近年来的研究热点。由于端到端时延的测量存在收发时钟不同步问题,所以常用的网络时延测量方法大多是通过测往返时延来间接求得端到端时延,测量结果的误差较大。文中基于GPS接收机的同步方法设计出网络时延测量仪来测量端到端时延,解决了收发时钟不同步的问题,提高了测量的精度。 相似文献
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由于端到端网络时延的测量中存在收发时钟不同步的问题,在测量中大多是通过测往返时延来间接求得端到端时延,测试结果误差较大。本文通过对IP网络端到端时延性能进行分析,提出主动探测方法:在互联网上通过在一端发送带有时间戳的IP数据包,在另一端记录该测量分组的到达时间戳来获得端到端的时延测量值,然后用线性规划的方法来消除收发时钟的初始相位差和相对频差等参数,估计出网络的端到端时延真实值。并以实例测试对此方法进行验证。 相似文献
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基于线性规划的Internet端到端时延的估计 总被引:3,自引:0,他引:3
测量Internet端到端时延特征是研究Internet端到端分组行为的重要内容之一,它能够应用于QoS(Quality of Service),SLA(Service Level Agreement)的管理、拥塞控制算法研究等许多方面.常用的端到端时延测量方法大多依赖于GPS接收机或采用NTP协议来实现收发端时钟的同步,但由于GPS接收机价格较高不可能每台主机都能配备, NTP协议的精度不能满足要求。该文基于线性规划的方法估计收发时钟的频差、相对时钟偏差等参数,以获得端到端时延的估计。作者在几条不同的链路上进行了测试,结果表明该方法能有效消除收发时钟不同步的影响。 相似文献
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在各类视频监控网络中,视频端到端的时延测试是一个令人困扰的问题,各设备制造商均无合适的端到端视频时延的测试工具。本文分析了视频端到端时延测试的主要难点,提出了一种适合视频端到端时延的测试方法,通过GPS或Internet网络解决了时延测试关键的同步问题,并利用数字图像识别技术自动分析出依附在视频上的同步时钟信息。 相似文献
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提出了一种测量和估计网络端到端单向排队时延的新方法。与消除时钟偏差和时钟频差的现有方法相比,新方法完全不需要测量端之间的时钟同步。探测分组之间的发送和到达时间间隔在两端分别测量,然后利用傅立叶域-时间域的迭代重构算法估计端到端单向排队时延的分布特性。仿真和分析结果表明新方法具有很好的实时性、准确性和顽健性。 相似文献
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针对LTE系统的DRX(非连续接收)机制进行介绍,系统分析DRX机制引入后对TD-LTE网络端到端时延性能的影响,并基于DRX机制打开和关闭前提对TD-LTE网络Ping包端到端时延进行对比测试分析。测试结果表明,DRX机制引入后,不合理的参数设置以及不同的UE(用户终端)处理能力将对网络时延性能产生影响。 相似文献
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Multicast Routing in Wireless Mesh Networks: Minimum Cost Trees or Shortest Path Trees? 总被引:4,自引:0,他引:4
Uyen Trang Nguyen Jin Xu 《Communications Magazine, IEEE》2007,45(11):72-77
There exist two fundamental approaches to multicast routing: shortest path trees (SPTs) and minimum cost trees (MCTs). The SPT algorithms minimize the distance (or cost) from the sender to each receiver, whereas the MCT algorithms minimize the overall cost of the multicast tree. Due to the very large scale and unknown topology of the Internet, computing MCTs for multicast routing in the Internet is a very complex problem. As a result, the SPT approach is the more commonly used method for multicast routing in the Internet, because it is easy to implement and gives minimum delay from the sender to each receiver, a property favored by many real-life applications. Unlike the Internet, a wireless mesh network (WMN) has a much smaller size, and its topology can be made known to all nodes in the network. This makes the MCT approach an equally viable candidate for multicast routing in WMNs. However, it is not clear how the two types of trees compare when used in WMNs. In this article we present a simulation-based performance comparison of SPTs and MCTs in WMNs, using performance metrics, such as packet delivery ratio, end-to-end delay, and traffic impacts on unicast flows in the same network. 相似文献
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NIRA: A New Inter-Domain Routing Architecture 总被引:2,自引:0,他引:2
In today's Internet, users can choose their local Internet service providers (ISPs), but once their packets have entered the network, they have little control over the overall routes their packets take. Giving a user the ability to choose between provider-level routes has the potential of fostering ISP competition to offer enhanced service and improving end-to-end performance and reliability. This paper presents the design and evaluation of a new Internet routing architecture (NIRA) that gives a user the ability to choose the sequence of providers his packets take. NIRA addresses a broad range of issues, including practical provider compensation, scalable route discovery, efficient route representation, fast route fail-over, and security. NIRA supports user choice without running a global link-state routing protocol. It breaks an end-to-end route into a sender part and a receiver part and uses address assignment to represent each part. A user can specify a route with only a source and a destination address, and switch routes by switching addresses. We evaluate NIRA using a combination of network measurement, simulation, and analysis. Our evaluation shows that NIRA supports user choice with low overhead. 相似文献
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无线传感器网络通常使用低占空比的异步睡眠调度来降低节点能耗。由于发送节点在接收节点醒来后才能向其发送数据,这将引入额外的等待时延。在最近的一些任播路由机制中,发送节点动态地选择最先醒来的候选节点转发数据,以最小化等待时延。但是,由于从最先醒来的候选节点到基站的时延可能并不低,任播路由机制并不一定能最小化端到端总时延。为此,提出了一种适用于异步无线传感器网络的机会路由机制,将路由决策建模为强马尔科夫过程,并根据最优停止理论推导出该过程一种简化的停止规则。仿真结果表明,节点到基站的最大端到端时延仅为基于地理位置的机会路由的68.5%。 相似文献
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End-to-end Internet packet dynamics 总被引:2,自引:0,他引:2
We discuss findings from a large-scale study of Internet packet dynamics conducted by tracing 20000 TCP bulk transfers between 35 Internet sites. Because we traced each 100-kbyte transfer at both the sender and the receiver, the measurements allow us to distinguish between the end-to-end behavior due to the different directions of the Internet paths, which often exhibit asymmetries. We: (1) characterize the prevalence of unusual network events such as out-of-order delivery and packet replication; (2) discuss a robust receiver-based algorithm for estimating “bottleneck bandwidth” that addresses deficiencies discovered in techniques based on “packet pair;” (3) investigate patterns of packet loss, finding that loss events are not well modeled as independent and, furthermore, that the distribution of the duration of loss events exhibits infinite variance; and (4) analyze variations in packet transit delays as indicators of congestion periods, finding that congestion periods also span a wide range of time scales 相似文献
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Several solutions are proposed to extend storage area networking solutions over distances of hundreds to thousands of kilometers. Native fibre channel or end-to-end fibre channel-based solutions can be offered over long distances using SONET-based networks. Protocols such as Internet SCSI (iSCSI), Internet fibre channel protocol (iFCP) and fibre channel over TCP/IP (FCIP) are being proposed to enable storage area networking solutions over networks that use IP as their transport protocol. Performance analysis of these solutions in terms of application throughput under variable network conditions of packet loss, bandwidth availability, extension distance, and TCP implementations in the sender and receiver is presented based on analytical modeling of different solutions. 相似文献
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互联网组播技术可以从根本上改善网络带宽的利用率,使发送者和路由器的处理消耗以及发送延迟降到最低的程度。IGMP是一种应用比较广泛的组播用户组管理协议,但是本身没有认证功能。PAP(密码认证协议)提供了一种简单的可以使端对端使用2次握手建立身份验证的协议。论文提出一种IGMP改进方案,把PAP认证协议添加在IGMP v3协议的扩展字段中,用于组播路由的最后一跳认证。 相似文献
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This letter considers an Internet streaming protocol (SP) for the transport of real time continuous data stream. SP makes use of measured network delay to optimally set retransmission time-outs and scale reliability. The sender streams out packets in a periodic manner, and a NACK is issued by the receiver if it does not receive an expected packet by a certain time. Although it may appear at first glance that the sender's and receiver's clocks must be synchronized, we prove that that the SP would work even if the clocks were not synchronized, a situation not uncommon in the Internet 相似文献