after a reboot virtual nics appear, where they are not configured

Dear community,

On two RHEL 6.4 Oracle RAC 11gR1 servers I get the following issue.

After a reboot, I get eth4:1 and eth5:1 nics. I see them when running
ifconfig

But I do not have /etc/sysconfig/network-scripts/ifcfg-eth{4,5}:1 config files.

Neither do I have any config files in /etc/sysconfig/networking/ subdirectories.
I also checked /etc/udev.d subdirectories.

Any place where I should look?
I do not know anything about RAC configuration files, so if you have a hint where to look. I would be grateful.

In parallel I opened a Red Hat case: 01367954

Kind regards,

Jan Gerrit Kootstra