en0相关问题？？？

# lsdev -Cc if
en0 Defined   1c-08 Standard Ethernet Network Interface
en1 Defined 1j-08 Standard Ethernet Network Interface
et0 Defined   1c-08 IEEE 802.3 Ethernet Network Interface
et1 Defined   1j-08 IEEE 802.3 Ethernet Network Interface
lo0 Available       Loopback Network Interface
如何更改en0的状态为Available?
谢谢各位！