对于SLIP和环回接口，在这里只有一个环回设备被创建，如果管理员适当配置SLIP项就可能有多个SLIP设备被创建.另外再附一个网络初始化-For SLIP and loopback interfaces, where only one loopback device is created, if the administrator is appropriate to configure SLIP items may have multiple SLIP equipment is create another attached to a network initialization