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 a