Turn off/on Cisco 877, dhcp and clock settings change to default

Unanswered Question
Aug 16th, 2007

After 2 days i got this router connecting to my ISP with PPPoA.

Do i have to manually add the ISP DNS entry?? I used ip negotiated option.

I'm using the scope, but when i turn the router off and on, it uses the default scope,

The same problem i have with time and date settings. It doesn,t keep the settings. I do apply the changes

The IOS version i think is 12.4(T7). I'm not near the router to check the IOS version.


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Richard Burts Thu, 08/16/2007 - 12:55


I wonder if these symptoms could be due to a setting of the config register? When you are at the router do a show version. Look at the very bottom of the display and there should be a line that gives the config register value. If it is set to 0x2142 you should change it to 0x2102.

When you say that you do apply the changes, does that mean that after making the changes that you do a copy run start?



ciscobiga Thu, 08/16/2007 - 13:36

This is my first Cisco router. I do know a few basic CLI commands, but not enought to configure the router.

I did all the configuration throught the gui (SDM).

Applying the changes i did throught the gui, and when i saw that after turning the router off and on the DHC scope changes back to default, i did a copy run start. But that didn't help either.

What is the command to change the config register value?

I'm not at the office right now, so i will check this tomorrow. Keep you posted.

Thanx Rick

ciscobiga Fri, 08/17/2007 - 00:29

The default config register value is 0x2101.

Any other suggestions for those issues?


Richard Burts Fri, 08/17/2007 - 02:27


The config register of 0x2101 would not produce these symptoms of not saving config changes. But it would impact the way that the router boots. I would suggest that you go into config mode (though the CLI) and enter config-reg 0x2102

This will set the config register to 0x2102 which is the normal default.

I am not very clear from your response about the exact order of what you have done. Did you make the changes (again) through SDM and after using SDM did you do copy run start? Or is the order different in some way?

If you make the change in SDM and then do copy run start, then the change should still be there when the router boots. Are you saying that you have done this and the change still is not there?



ciscobiga Fri, 08/17/2007 - 04:47

I started to configure this router 2 days ago through SDM express.

I couldn't get it working the first day, so the second day when i turned it on i saw that the dhcp scope was back on the default instead the i configured. The same for time and date settings.

I don't know if applying the changes with SDM express is similar as copy run start.

So i configured the DHCP scope and time settings again, save the settings with Express, turned the router off/on and settings didn't save.

Did the config again, but also this time did a copy start run.

I must say didn't turned the router off after doing this.

I posted this issue on the forum.

During the day i noticed the more advanced tool SDM, and start using that configure the router, and at the end of the day it worked.

Today i installed the new SDM version on my PC and on the router.

To make a long story short, i turned the router off a few times, and i noticed that the DHCP settings where saved. I don't know what solved this. Was it using the copy run start,(but didn't reboot it afterwards) are using SDM instead of the Express version?

Only the time and date settings aren't saved.

The config register is 0x2102. I think i made a typo error on my prior post.

Richard Burts Fri, 08/17/2007 - 06:37


I do not think that we know for sure at this point whether what solved this issue, it certainly could have been the copy run start or it could have been using SDM instead of the Express version. I am not familiar with the Express version (and only slightly familiar with SDM) so can not say for sure what it does. I personally regard it as a very flawed implementation if something gives you the ability of make changes but does not make it easy to save those changes to the startup config.

As for the time and date settings it depends on the model of router. Some of the routers (especially the higher end) have a clock chip that does remember time and date over a reboot. And some of the routers do not have the chip and do not remember the time and date over a reboot. Especially for routers like those it is a very good idea to run NTP so that the router can learn time after a reboot. NTP works very well and is quite simple, if your router has access to the Internet where there are a number of available NTP sources.




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