[物理层](%E7%89%A9%E7%90%86%E5%B1%82.md) [数据链路层](%E6%95%B0%E6%8D%AE%E9%93%BE%E8%B7%AF%E5%B1%82.md) [网络层](%E7%BD%91%E7%BB%9C%E5%B1%82.md) [传输层](%E4%BC%A0%E8%BE%93%E5%B1%82.md) [应用层](%E5%BA%94%E7%94%A8%E5%B1%82.md)