2811 router clock issue

[Mohammed Idris]

We have 2 cisco 2811 routers and both of them are showing clock (software and hardware) and date as Nov 1933. I did set the software clock as current time and date and then use clock update calendar command to update its hardware clock. After switching off and then on, it looses it clock again to Nov 1933. Is there any way to fix this issue?

[Mohammed al Baqari]

Configure your routers to sync with NTP server and save the config.

command:

ntp server x.x.x.x preferred

[Mohammed Idris]

Thanks. I want to make it's clock correct so that I can use this as ntp sserver. By using another ntp server iit corrects it's clock but looses after switched off. 

[Terry Cheema]

The router has two clocks software and hardware. Software clock is the one you configure and is stored in config and is lost when router is rebooted. Hardware clock is maintained even when the router is powered off using a battery that keeps the clock running (like the ordinary watches).

Ref: http://www.cisco.com/c/en/us/td/docs/routers/access/2800/hardware/installation/guide/hw/01_hw.html#wp1038275

Real-Time Clock

An internal real-time clock with battery backup provides the system software with time of day on system power up. This allows the system to verify the validity of the certification authority (CA) certificate. In the Cisco 2811, Cisco 2821, and Cisco 2851 routers, the clock and battery are permanently installed; the battery lasts the life of the router under the operating environmental conditions specified for the router. The Cisco 2801 router has a socketed lithium battery. This battery lasts the life of the router under the operating environmental conditions specified for the router, and is not field-replaceable.

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Note If the lithium battery in a Cisco 2801 router should fail, the router must be returned to Cisco for repair.

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Although the battery is not intended to be field-replaceable, the following warning must be heeded:

So all you need to do is set your clock and then run the command "clock update-calendar" to copy the software clock into the hardware clock. After that router should take care of the hardware clock and when you reboot the time should be displayed from hardware clock.

If this is not happening it may be an issue with the hardware clock battery.

-Terry

Please rate all helpful posts

[Wilson Samuel]

Great info Terr (+5)

Just adding one more point:

You could correct router clock by the clock command at the enable prompt (and NOT at the config mode) by the following command:

Router# clock set 13:32:00 13 July 2015

This would set the clock to the current time and then the synchronization to the NTP makes it easier :-)

After that, make sure you see the show ntp associations to see that ntp has indeed been associated with the server and in synch, as example given belwo

Router#show ntp associations 

address            ref clock         st      when    poll   reach   delay   offset    disp 
~172.31.32.2       172.31.32.1       5       29      1024   377     4.2     -8.59     1.6 
+~192.168.13.33    192.168.1.111     3       69      128    377     4.1     3.48      2.3 
*~192.168.13.57    192.168.1.111     3       32      128    377     7.9     11.18     3.6 
* master (synced), # master (unsynced), + selected, - candidate, ~ configured

HTH

[will.alvord]

Wilson's right. You'll always want to manually set the clock as closely as possible to the accurate time. The NTP sync will be a lot quicker.

[Mohammed Idris]

This info I  found here in support forum and I did the same if you see my post initially. I also doubted on battery. is it possible to replace the battery by any chance? Because they say it should be sent to Cisco to do so. I mean has anyone done this?

[yahsiel2004]

It's more then likely a bad battery and I believe it is soldered on. So, if  you can de-solder it off, you can replace it.

HTH

Yosh