Configuration register for tftp boot 4

[silverhairb]

Before I just walk downstairs to the 3660, yank out the 24meg of old flash and insert 64meg, I just want to make sure - REALLY SURE - that when the system boots, it will go out to the tftp server and ask what file to load for boot. Then I can copy the boot image to flash, change the config register and boot from flash.

In this scenario, is it correct to change the config register to 0x2124 (router# config-register 0x2124)?

[the other] Bill

 

[burtsbees]

No---that just sets BAUD to 19,200, but it will still boot the config from NVRAM. You want
rommon1>confreg 2142
or
router#config-reg 0x2142

2142, not 2124---the last 2 digits you have transposed...remember...Meaning of Life...42...

NOW who's cross-eyed???lol

Burt

 

[silverhairb]

OK. Thanks.

What should the regular conf reg be set to when all is said and done for normal operation / 9600 baud? I seem to be stuck at 19200.

(I cheated and got the memory upgraded using a PCMCIA flash card to load a small image 3660 IOS from hunter, then copied the actual IOS that was running of the router from the tftp server.)

[the other] Bill

 

[CiscoGuy33]

Bill,

It should be Ox2102

E.A. Broda
CCNA, CCDA, CCAI, Network +

 

[silverhairb]

Since the memory upgrade and reload of IOS, the 3660 keeps trying to default back to 2122. I can drop into rommon and reset it to 2102 and reset, but sometime during the IOS load is changes back to 0x2122. I know I did something wrong when I reset the conf reg just before the IOS reload (had to switch to 19200 baud).

Did I do something to change the default in the IOS? Do I need to erase flash and reload the 3660? (It really is a beast. )

[the other] Bill

 

[Cluebird]

This will fix the issue:

Router#config t
Router(config)#config-register 0x2102
Router(config)#end
Router#copy run start
Router#reload

The box only looks at config-register on initial boot, after POST when the bootstrap code loads from ROM.

 

[silverhairb]

Thanks, but it keeps jumping back to 2122.

Maybe tomorrow, I'll erase the flash, reboot into rommon (break init), reset the conf reg to 2102, boot onto PCMCIA flash and then reload the IOS from tftp while its in 0x2102. See if that works.

I don't mind the 19200 baud except that I can't just change the terminal from one router to another without changing the properties (using an XP PC as a terminal).

[the other] Bill

 

[burtsbees]

In rommon, DO NOT use 0x2102---you MUST use simply
rommon1>confreg 2102
rommon2>reset

You MUST reset after the change.
Tad---I have never had problems doing it this way, I.E. I have never had to boot the router and change it in the IOS, where this was the only way it works. I assume you have?

Also, I am not sure about the 3600's...they don't use the overwrite register in rommon, do they Tad?
rommon1>o/r 0x2102
rommon2>reset

That I DO believe uses the "0x".

"I cheated and got the memory upgraded using a PCMCIA flash card to load a small image 3660 IOS from hunter"
Why? You can upgrade, downgrade or simply change the IOS code while the router is running---if there is not enough room on flash, I believe it will squeeze it, but I am not sure...
Any time I upgrade a router, I do this after a reload...
router#squeeze flash

Burt

 

[silverhairb]

Burt, I replaced the 8meg + 16meg flash sticks with 2 x 32 meg and had no IOS in the router. It wasn't a matter fo squeezing, there justs wasn't anything there. I originally changed the configuration register to what I thought would try to boot from tftp. That's where I made my mistake.

I copied an image of a small earlier version of IOS to a PCMCIA flash card and booted from that. Then I was able to copy the correct IOS from the tftp server to flash. The "cheat" part was that I used the PCMCIA flash card. But maybe its not cheating as much is it was just doing whatever it took.


[the other] Bill

 

[Cluebird]

Burt,

I had a box years ago that required me to reset the config-register a couple times. When you're dealing with the baud rate, you'll need to disconnect the terminal you're using after you reset the baud, then reconnect using the new settings of 9600. Otherwise, the console often stays at the "old" baud rate.

The 3600s use the confreg utility from rommon instead of the o/r command.

Try this: rommon>confreg 0x2102
rommon>reset

Disconnect your terminal, then reconnect after boot.

I'm looking at the 2102 and 2122 registers with a utility I've got to see what the difference is between them. My utility doesn't show any difference in the boot with those settings. Will check a couple other things, though.

 

[Cluebird]

Forgot to include this link:

http://www.cisco.com/en/US/docs/routers/access/3600/hardware/installation/guide/3600appC.html

 

[silverhairb]

Clue,

What I found in the Configuration Register documentation is that the difference between 2102 and 2122 is the console baud rate. That's the sticking point for me. I can't just simply unplug the console cable from the 3660 and plug it into either of the 3640s or 831s.

I will try again this afternoon. Was assigned a couple of honey-do's and they have a higher priority than anything lab-related.

[the other] Bill

 

[silverhairb]

Burt,

I'm not using the 0x when in rommon, only when in the IOS. That was something you taught me with the 831s and 877.

At my age, I might have trouble with short-term memory, but that was long enough back for it to be burned in pretty good.

[the other] Bill

 

[maczen]

Tad,
What is the name of the utility that you mentioned (checks differences between config registers)???

Bill,
0x2122 should be fine as long as you set all of your routers/switches to the same baud so that you can quickly plug/unplug until you get an access server! Here is a cool link that explains some of the differences between the config regs and has a link to a good utility for checking the differences.. Not sure if it is the same tool that Tad uses..

http://www.ciscozine.com/2008/09/23/the-configuration-register/

Here is the link to the tool (Boson):

http://www.boson.com/FreeUtilities.html

B Haines
CCNA R&S, ETA FOI

 

[Cluebird]

Mac,

I have a utility I picked up while teaching with the Cisco Networking Academy call confregna. The Boson one in the link is good, too.

TOB,
I've had the issue you're describing with the register not seeming to accept the slower baud. I fought with it after I did an xmodem transfer of IOS to a router years ago. It finally set when I used the rommon utility confreg to set the baud, disconnected my terminal (physically pulled the cable out), power cycled the router,changed the terminal settings (and plugged the cable back in) and reconnected the terminal at 9600 baud. It is very non-intuitive, but that is part of the secret handshake with Cisco. Play with it. You might even use two different terminal programs. Back then I used Tera Term and Hyperterminal Private Edition.

Or for a nominal fee...

 

[silverhairb]

Clue,

I'll give that a shot tomorrow. My current blood alcohol content would lead to too many fat-finger faults and possible logic errors. But since the process seems to be counter-intuitive, maybe a little extra wine is called for.

[the other] Bill

 

[silverhairb]

Twas a bit different problem.

Every time I tried to change the configuration register either in rommon or through an IOS command, it kept reverting to a value for 19200 console speed (2102 to 2122, 2142 to 2162). Very frustrating. The router seemed to be getting to 9600 but during the IOS load process it would display an error message "GT6420 TIMER INTERRUPT" (might have been GT6421) and thought it might be a hardware problem.

But I wasn't about to give up that easily.

After booting into 19200 with the conf reg set to 2162 (tried 2142, but system reset it), I decided to look at the running config. There was one little line under the console definition at the end of the running config that said "speed 19200". Ahhh, the culprit was discovered!! Changed it to 9600, wrote the changed to startup, reset the config register to 2102, saved, power cycled. Worked. Power cycled a few more time, worked every time.

Might try setting the conf reg to 2142 to see if the router reverts back to 19200. No problem, it dod not go to 2162. Tried several other things as a kind of diagnostic check, all kept coming back to 9600 baud rate.

So the bottom line is that the router is back to 9600.

Thanks for the help and suggestions. It started the thinking process.


[the other] Bill