I have a question indirectly related to oVirt - I have a VM with CentOS 6 running on my cluster, which has 6 virtual interfaces (eth0 - eth5). Now its a time to do an upgrade to CentOS 7 based, and I did a VM clone to test an upgrade process and was a bit surprised to see that now I have interface names shifted  eth6 - eth11. I would afraid that I'll run out of digits soon :) 

Anyway how to change the interfaces names back to originals and perhaps prevent them form the further changes? I do understand that MAC address has changed, but don't get why it changing the interfaces names. 

Cleaning up everything from /etc/udev/rules.d/70-persistent-net.rules doesn't really helped ..