IP packet generation: statistical models for TCP start times based on connection-rate superposition
IP packet generation: statistical models for TCP start times based on connection-rate superposition
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IP数据包生成：基于连接速率叠加的TCP启动时间统计模型
DOI：
10.1145/339331.339413
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Don X. Sun
中科院分区：
文献类型：
--
作者：
W. Cleveland;D. Lin;Don X. Sun
HTTP 的 TCP 启动时间是不稳定的。出现非平稳性的原因是，一条链路（一个点进程）的起始时间是源流量点进程的叠加，并且叠加的统计量随着叠加进程个数的变化而变化。起始时间率是流量源数量的衡量标准。到达间隔时间的单变量分布近似为 Weibull，并且随着速率的增加，Weibull 形状参数变为 1，呈指数分布。对数到达间隔时间的自相关由一个简单的两参数过程来描述：白噪声加上长程持续时间序列。随着速率增加，持久序列的方差趋于零，因此对数时间趋于白噪声。对数间隔到达的简约统计模型解释了自相关、威布尔分布以及两者与速率的非平稳性。该模型的目的是向网络模拟器提供随机输入，具有叠加点过程作为单个流生成的理想特性。模型的参数是速率的函数，因此要生成开始时间，只需指定速率。随着速率的增加，模型趋于泊松过程。这些结果来自基于连接率叠加概念的理论和实证研究。理论是叠加点过程的数学，经验主义是对 2300 万个 TCP 连接的分析，这些连接被组织成 10704 个块，每个块大约 15 分钟。
TCP start times for HTTP are nonstationary. The nonstationarity occurs because the start times on a link, a point process, are a superposition of source traffic point processes, and the statistics of superposition changes as the number of superposed processes changes. The start time rate is a measure of the number of traffic sources. The univariate distribution of the inter-arrival times is approximately Weibull, and as the rate increases, the Weibull shape parameter goes to 1, an exponential distribution. The autocorrelation of the log inter-arrival times is described by a simple, two-parameter process: white noise plus a long-range persistent time series. As the rate increases, the variance of the persistent series tends to zero, so the log times tend to white noise. A parsimonious statistical model for log inter-arrivals accounts for the autocorrelation, the Weibull distribution, and the nonstationarity in the two with the rate. The model, whose purpose is to provide stochastic input to a network simulator, has the desirable property that the superposition point process is generated as a single stream. The parameters of the model are functions of the rate, so to generate start times, only the rate is specified. As the rate increases, the model tends to a Poisson process. These results arise from theoretical and empirical study based on the concept of connection-rate superposition. The theory is the mathematics of superposed point processes, and the empiricism is an analysis of 23 million TCP connections organized into 10704 blocks of approximately 15 minutes each.