I am using RHEL 6. when i try netconfig its give an error message "bash netconfig command not found". I try with SU. i was checked in /etc/sbin but i didnt find the command.

I'm not aware of a command in RHEL called "netconfig".

Where did you see this command? If you do a "which netconfig" on the system where it exists you can see the path to it. If you do "file $(which netconfig)" you can see what kind of file it is. It seems likely that if you've seen this it is either:
1) A script/command someone manually put in place on the server on which you're seeing it and you'd have to migrate it to your new server.
2) Something used by a specific distro (e.g. Ubuntu or Slackware) that isn't available in other distros (e.g. RHEL or Suse). If that is the case you'd have to find out what the equivalent tool for RHEL is.

What exactly are you wanting to do with the netconfig command? There may be other tools that do it on RHEL.