Ethernet ports should be connected and link prior to changing it's settings to minimize confusion.
Changing the ifcfg-eth? file from CLI seems to automatically restart the port and the changes takes place automatically, so change the IP of eth? and do ifconfig shows the new changes without having to restart the port manually and the port is functional with the new IP.
ifcfg-eth? files in /etc/sysconfig/network-scripts
Tested with static IP settings, DHCP work the same? On MDS and Venice 2u with RHEL 6.2.