Cisco 3640 Routers not loading startup-config on reload

Answered Question
Feb 6th, 2008

Hi all,

I'm a CCNA who has spent some time away from the gear, and am getting back into it. Just purchased two 3640 routers and a 2950 Enhanced Image switch to practice/learn/relearn. Running into a problem that I'm sure is very simple, and feel very silly I can't figure it out.

I make changes to my running-config and do a "copy run start". When I reload or power cycle the units, some of the configuration loads (ip addresses) but other items do not (hostname, no shut command on interfaces, etc). If I do a copy start run after the reload, everything is hunky dory again (until the next time I powercycle or reload the routers).

if you need anything (sho ver, sho run, etc - let me know). Thanks in advance for any and all help.

Jim Woodward

I have this problem too.
0 votes
Correct Answer by Richard Burts about 8 years 9 months ago

Jim

The configuration register is a 16 bit register which controls several aspects of the behavior of the router, probably most important are the speed of the console port, whether to boot from flash, whether to honor the break key, and whether to read the startup configuration from NVRAM or ignore it. If you want to get more details about the configuration register this link has some very good information:

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a008022493f.shtml

The short version is that 0x102 or 0x2102 will read the startup config from NVRAM, will only honor the break key during the very early part of the boot sequence but not after that, will boot from flash, and have console speed of 9600. Changing the register to 0x2142 tells the router to ignore the startup configuration in NVRAM at bootup. This is a common part of doing password recovery to set the register to 0x2142. And it is fairly common that people forget to change it back after the recovery is completed. And then they run into the problem that you have had.

If the config register was 0x2142 then I would suggest setting it to 0x2102 rather than 0x102. The difference is that 0x2102 will Boots into ROM if initial boot fails while 0x102 does not include that.

HTH

Rick

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (5 ratings)
Loading.
guruprasadr Wed, 02/06/2008 - 21:28

HI James, [Pls Rate if HELPS]

Use command:

cisco#write memory

The router's configuration information is stored in a device called the Nonvolatile RAM (NVRAM), and the IOS images are stored in a device called the flash.

PLS RATE if HELPS

Best Regards,

Guru Prasad R

jamesawoodward Sat, 02/09/2008 - 18:41

Thank you so much, Dandy. The config-register was set to 0x2142. I looked around a bit for info online before posting here, and actually changed my config-register to 0x2102, but that did not work. I just reset my hostname on 1 router, changed the conf-reg to 0x102, did a 'copy run start' and then reloaded the router and it booted up with my hostname. So your solution was perfect. If the silly "resolved my issue" checkbox was available now (after I rated your post 5.0), I would check it. But it's not there. Anyway - thank you very much for your help. I greatly appreciate it. One more question for you, though:

What exactly does config-reg 0x102 do? I could find no documentation that stated that 0x102 booted IOS from flash and the running configuration from the saved startup-config.

Thanks Again!

Jim Woodward

Correct Answer
Richard Burts Sun, 02/10/2008 - 13:34

Jim

The configuration register is a 16 bit register which controls several aspects of the behavior of the router, probably most important are the speed of the console port, whether to boot from flash, whether to honor the break key, and whether to read the startup configuration from NVRAM or ignore it. If you want to get more details about the configuration register this link has some very good information:

http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a008022493f.shtml

The short version is that 0x102 or 0x2102 will read the startup config from NVRAM, will only honor the break key during the very early part of the boot sequence but not after that, will boot from flash, and have console speed of 9600. Changing the register to 0x2142 tells the router to ignore the startup configuration in NVRAM at bootup. This is a common part of doing password recovery to set the register to 0x2142. And it is fairly common that people forget to change it back after the recovery is completed. And then they run into the problem that you have had.

If the config register was 0x2142 then I would suggest setting it to 0x2102 rather than 0x102. The difference is that 0x2102 will Boots into ROM if initial boot fails while 0x102 does not include that.

HTH

Rick

jamesawoodward Thu, 02/14/2008 - 14:44

Hi Rick,

Sorry for the delay in my reply. My Cisco 1602 router running 11.1 which I haven't used in a couple years also had the config-register set to 0x2142. I had set it to break into the router and forgot to set it back myself. Both new routers (2 3640's) came from the company configured that way also.

Thank you very much for the info! I appreciate it alot.

Cheers and good day!

Jim Woodward

Danilo Dy Mon, 02/11/2008 - 15:34

Hi,

I prefer 0x2102 over 0x102 as already mentioned by Rick (5 points :) ), I only use 0x102 for troubleshooting.

Here is the configuration register settings and router behavior (post it since its in my notepad :) ).

0x102 - Ignores break, 9600 console baud

0x1202 - 1200 baud rate

0x2101 - Boots into bootstrap, Ignores break, Boots into ROM if initial boot fails, 9600 console baud rate

0x2102 - Ignores break, Boots into ROM if initial boot fails, 9600 console baud rate default value for most platforms

0x2120 - Boots into ROMmon, 19200 console speed

0x2122 - Ignores break, Boots into ROM if initial boot fails, 19200 console baud rate

0x2124 - NetBoot, Ignores break, Boots into ROM if initial boot fails, 19200 console speed

0x2142 - Ignores break, Boots into ROM if initial boot fails, 9600 console baud rate, Ignores the contents of Non-Volatile RAM (NVRAM) (ignores configuration)

0x2902 - Ignores break, Boots into ROM if initial boot fails, 4800 console baud rate

0x2922 - Ignores break, Boots into ROM if initial boot fails, 38400 console baud rate

0x3122 - Ignores break, Boots into ROM if initial boot fails, 57600 console baud rate

0x3902 - Ignores break, Boots into ROM if initial boot fails, 2400 console baud rate

0x3922 - Ignores break, Boots into ROM if initial boot fails, 115200 console baud rate

Sry for late reply, I was too busy troubleshooting my PC for 2 days. After upgrading to Windows Vista, my NIC, SC, CD-ROM Drive, VPN Client doesn't work. Need to buy new NIC as LinkSys FastEthernet (not GE) NIC does not support Windows Vista (driver download URL say NO).

Regards,

Dandy

jamesawoodward Thu, 02/14/2008 - 14:46

Hi Dandy,

Thank you as well very much for your help and for your knowledge. I hope Windows Vista works well for you. I'm going to have to buy a new laptop for my wife, and it will be Vista, unfortunately. Can't wait to see what bugs and issues that brings me.

Thank you again. Cheers!

Jim Woodward

Danilo Dy Fri, 02/15/2008 - 22:06

Not good. Infected by Virus after 3 days with Norton Internet Security 2008 present :(

Now, I'm wrestling with my internet connectivity, it's ON/OFF and need to reboot the modem many times to get a connection.

jamesawoodward Mon, 02/18/2008 - 16:39

Oh geez - I'm sorry. A friend's computer had all sorts of nasty stuff - 57 open internet explorer windows all warning that his computer was infected with viruses and spyware - and more popping open every minute or two - grrrr - hate that stuff.

I hope you resolve your problems. If by chance you have a Mac that you want to connect to and use resources from, and you run into problems where you enter the correct username and password but can't connect - ask me about it. Because I ran into that particular bit of silliness and rectified it.

Anyway - thanks again for your help. I'm sure I'll be back w/a few (i.e. many) more Cisco questions to scour your (and everyone else's as well) brain with.

Cheers and good luck!

Jim Woodward

Actions

This Discussion