osi七层模型最真实的体现，学习网络必须要的东东。 osi七层模型最真实的体现，学习网络必须要的东东。-model osi seven truest reflection of the learning network to Dongdong. model osi seven truest reflection of the learning network to Dongdong. model osi seven truest reflection of the learning network to Dongdong.