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Community Member

confreg on sup720 was wrong

Hi guys.

I got a call from a customer where they said that they cant get a 6504 with a Sup720 too boot properly. Thay had it working on friday. they did a couple of test runs on some configurations and the last thing they did was a Write Erase.

On Monday Morning, they were going to reconfigure the sup720 to be deployed, but it booted only in to rommon.

It booted when given the boot command in rommon. We did a check of the sh bootvar, and everything was as it should be. here is the result of sh bootvar:

BOOT = disk0:s72033-ipservicesk9_wan-mz.122-18.SXF8.bin,1;



Configuration register = 0x2102

After a couple of rebootes i did a confreg in rommon on a whim, and the boot variable was set to 0x2100. After i changed the confreg to 0x2102 the 6504 boots into IOS as it should.

Now to my question, arent sh bootvar going to fetch the value from rommon and display the values. And how can the confreg be changed when the only command the customer did was write erase.


Jocke W

Cisco Employee

Re: confreg on sup720 was wrong

Hi Jocke,

When Cat6k is running in Native mode then there are 2 places where config reg need to be set, one is for msfc and one for sup but when you just run "sh boot" you will see config reg which is set on MSFC.

But when you issue command "remote command switch sh boot" you will see boot var set on sup engine.

Now you never know what was changed and what test were run and may be because of that config reg might have been changed for sup. So I believe when you issue "sh boot" you see config reg value set on msfc but you never know some one might have chnaged it for sup.



*Pls rate all helpfull post

Community Member

Re: confreg on sup720 was wrong

Thanks for the Reply.

Now i understand how this works. Sorry for the low rate, i messed up when rating your answer.

Re: confreg on sup720 was wrong



As per u r reply can u please explain how SP and RP works in native IOS.



Re: confreg on sup720 was wrong


Simply, when the switch starts, the switch processor (SP) boots up first. After a short amount of time (approximately 25 to 60 seconds) it transfers console ownership to the route processor (RP (MSFC)). The RP continues to load the bundled software image.

After the RP loads the IOS, you can send commands to the SP, simply execute the remote command from the RP exec prompt "remote command switch ".

Use the following link for further info:

Comparison of the Cisco Catalyst and Cisco IOS Operating Systems for the Cisco Catalyst 6500 Series Switch

HTH, please do rate all helpful replies,

Mohammed Mahmoud.

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