1. Check this file /etc/sysconfig/network-scripts/ifcfg-ethX, and find there is no MAC address of the port in it. It can tell us this file was edit by customer manually, cause there should be MAC address in it if customer configure it by system-config-net tool.
The picture of edit by customer manually.
The picture of configured by tool:
2. It is necessary to bond the MAC address in /etc/sysconfig/network-scripts/ifcfg-ethX in Redhat 5.4 when the system have more than 2 ports. Otherwise the port name will be changed after rebooting.