udev: renamed network interface eth0 to _eth0_

Issue

After upgrading from RHEL 6.4 to RHEL 6.6, the eth0 network interface is inaccessible and the server is offline. A review of /var/log/messages shows some of the following messages:

udev: renamed network interface eth0 to _eth0_

When I try to bring up eth0, I get the following error:

root@localhost>ifup eth0
bnx2 device eth0 does not seem to be present, delaying initialization.

and

root@localhost>ifconfig eth0
eth0: error fetching interface information: Device not found