Configured Networking of Gateway in some machines.
But difference was found to configuration.
"ifcfg-eth1 and ifcfg-eth2" of one machine are different from other things.
The "HWADDR= ...." isn't described there.
Is it a problem?
The problem occurs when the target interface doesn't exist. (or disable)
It is solved in the following method.
01. Enable the target interface.
02. Configure Networking again.