Each layer USES the layers beneath it, so the network layer does not need to worry about how each hop on the network USES the physical and data link layers and so forth.
每一层都使用它下面的层，因此网络层不必担心网络上的每次跳转如何使用物理和数据链接等问题。
The various network device drivers run at the interface layer, which receives and transmits data from and to the physical link.
各种网络设备驱动程序在接口层运行，该层从物理链路接收数据，并向物理链路传输数据。
Main points of the model implementing scheme and designing idea are respectively given for physical layer, data link layer, application layer and user layer.
分别给出物理层、数据链路层、应用层、用户层的模型实施方案及技术要点的设计思想。
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