AUI 端口是用来与粗同轴电缆连接的接口，它是一种"D"型15针接口，这在令牌环网或总线型网络中是一种比较常见的端口之一。路由器可通过粗同轴电缆收发器实现与10base-5网络的连接，但更多的是借助于外接的收发转发器（AUI-to-RJ-45），实现与10base-T以太网络的连接。当然也可借助 于其他类型的收发转发器实现与细同轴电缆（10base-2）或光缆（10base-F）的连接。这里所讲的路由器AUI接口主要是用粗同轴电缆作为传输 介质的网络进行连接用的。
c) MediaIndependent Interface (MII). It is anticipated that some DTEs will be connected to a remote PHY, and/or to different medium dependent PHYs. The MII is defined as a third compatibility interface. While conformance with implementation of this interface is not strictly necessary to ensure communication, it is recommended, since it allows maximum flexibility in intermixing PHYs and DTEs.The MII is optional.
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