要想在已经配置的以太网卡上添加额外的ip别名，应该为一个接口配置同样的物理单元号，但是要用一个逻辑单元号来限定它。

To add an additional IP alias to an Ethernet card that's already configured, you configure an interface with the same physical unit number but qualify it with a logical unit number.

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模型/逻辑单元处理所有的 ClearCase 用户接口和命令行；相反，片断则存在限制。

Model/LUs work with all ClearCase user interfaces and the command line; whereas, limitations exist regarding Fragments.

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