The mastery of network simulative tools is important for network pursuers due to increasing of complexity, scale of networks. Free NS is amply discussed in this paper.

• 摘要通信网络的日新月异，各种网络方案和协议日趋复杂、网络规模日趋庞大，对网络研究人员而言，掌握网络仿真的重要性是不言而喻的。着重探讨网络仿真免费软件NS。