说明：  由于网络本身的复杂性，要分析网络性能显得比较困难。然而随着计算机技术的发展，仿真已经成为一种分析复杂系统的有效的工具。介绍了目前应用较为广泛的网络仿真器NS一2。首先详细介绍了网络仿真器 NS一2的结构、功能及使用方法。给出一应用实例，其次介绍NS一2的扩展方法。
(As the complexity of the network itself, to analyze network performance seemed more difficult. However, with the development of computer technology, simulation of complex systems has become an effective tool. Describes the current common network simulator NS-2. First details of the network simulator NS-2' s structure, function and use. One application example is given, followed by NS-2 describes the extension method.)