Under CentOS6, is it possible to get an interface to RUNNING state without assigning a (dummy) IP address? # ifconfig em2 em2 Link encap:Ethernet HWaddr 78:2B:CB:67:3E:5C UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 b) TX bytes:0 (0.0 b) This was working fine on RHEL3 simply by running ifconfig up. # ifconfig eth1 up # ifconfig eth1 eth1 Link encap:Ethernet HWaddr 00:11:25:57:8B:2D UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:10658057 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:1169901971 (1115.7 Mb) TX bytes:0 (0.0 b) Base address:0x3400 Memory:d0240000-d0260000 # dmesg |grep eth1 ... e1000: eth1: e1000_watchdog: NIC Link is Up 1000 Mbps Full Duplex # provided there is a link.