If you ever cloned an installation of SLES (SuSE Linux Enterprise Server) you may find on the systems you have copied your image to that your active network connections do not start at eth0.  This is because SUSE uses a udev rule to create persistent binding to eth interfaces.

You can fix this situation with the following steps.

Remove all existing Ethernet configuration files from the system configuration.

rm /etc/sysconfig/network/ifcfg-eth*

Then remove all the lines that start with the string "SUBSYSTEM" from the appropriate udev configuration file.

sed -i '/^SUBSYSTEM/d' /etc/udev/rules.d/30-net_persistent_names.rules

Then reboot the system.  As the system reboots udev will create new rules using the lowest available eth addresses (which should now be eth0).  You can then configure the network devices as normal.

In future you can avoid this situation by clearing the udev file and the relevant system configuration files prior to cloning. 

Always remember to back up any system files before deleting or editing them :)