The deal is, I was going to change the IP address, router and subnet mask of this AIX box so, I used "smit mktcpip" and made the changes. Simple, right? Doh!

Now, because I didn't use rmyp -c (ignorance!) before the changes, and the machine has a new IP address but, no new yp info, it will not boot. Nor can I get it booted to single user mode (if there is such a thing in AIX).

I'm stuck. This machine will not boot on the network, I am not able to get it into single user mode to make the necessary changes, and booting in diag mode (wrench setting) offers no recognizable help. I've tried booting from a CD but, I can't figure out how to change the firmware to boot from the CD.

I do have a console connection via a Lantronix terminal server but, "send brk" isn't working and the diag menu doesn't offer a single user boot mode.

Where do I go from here (besides to the house)? Does anyone have any idea how to break into this machine so that I can get it configured for the new network?

Any and all help will be greatly appreciated!!

To boot from CD : It depends on the model of server, but basically you boot it up and after a few minutes it pops up with the RS/6000 logo (or on a terminal "RS/6000" repeated a lot. After "keyboard" pops up, you've got a few seconds to hit the right key - normally 1 - to enter the SMS menu. From here you can pick the bootlist and put cd0 at the front.

When you boot from CD and you've picked the terminal and language, pick option 3 and access the root volume group.

@jstan : your problem is coming from somewhere else.
Changing the IP address should not prevent the system from booting. It simply prevents you using the Graphic Display in a Regular Desktop Session, but you could login in a Failsaife session (regular X11 session) or in console mode. Even, the Yellow page problem still allows you to telnet the box using the full IP address. So, if the system really does not boot, I guess that there is an extra problem, like /tmp filesystem full.
Nevertheless, the ianr solution booting from CD should help.

Got It! Yayyy!!

Not being familiar with AIX (and now, not wanting to be :>) I wasn't sure how to get to a single user mode. Because the network settings had changed to a new subnet and there was no NIS server on the subnet, the machine would hang at trying to contact the NIS server and would not boot. So, I needed to get it into single user mode to make the necessary adjustments but, didn't realize how to do it.

Booting in diag mode provided a sketchy menu but, eventually I figured out that I needed to enter a recovery mode, but that only put me into the ram with a very limited shell. At that point I was able to mount /dev/hd4 to /mnt, cd to /mnt/etc and rename the rc.nfs file. Then I rebooted in normal use mode and the machine came up and allowed me to log in as root.

From there, it was simply a matter of messing around with smit and making the necessary changes.

Sounds simple but, for my simple mind, it was quite the task.

Anyway, thanks to those who responded. It's nice to know there are forums where one can get professional help (IT and otherwise).

rc.nfs things means that the system tried to nfs-mount remote systems before booting. And mounting them in foreground mode instead of background mode.

I'm happy that everything works now, congratitulations !