I added some virtual IPs to my eth0 interface in CentOS 6.5,
ip addr add 192.168.100.2 dev eth0
I then simply added a VLAN on eth0.
vconfig eth0 10
The VLAN was created but it removes any of my added IPs on eth0 (eg. 192.168.100.2).
I didn't face this issue in CentOS 5.X. The eth0 retains IPs.