just to add these links from upstream: https://bugzilla.redhat.com/show_bug.cgi?id=714035 https://bugzilla.redhat.com/show_bug.cgi?id=645796
Both state basically that vconfig is scheduled for removal from upstream, allthough it is not stated in which release.
Err... I feel like I've gone back a week....
You can use the following command instead of vconfig:
ip link add dev ${DEVICE} link ${PHYSDEV} type vlan id ${VID}
Here's the thread on this ML with an identical subject line where this was discussed:
http://lists.centos.org/pipermail/centos-devel/2012-August/008752.html