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2600 config register issue in both Rommon and IOS

I have a one 2611 and two 2621 routers that all the config-registers have a value of 0x3922 and when I change it to either 0x2102 or 0x2142 they change to a different 3900 value. The second problem I encountered was that in rom I can't use the tftdnld feature, it times out even with all the right parameters set and the tftp server local to the router. I have 5 other 2600 routers with the right config-register and the tftpdnld works find.

I was thinking that the nvram might be corrupt I just don't know. The router seems to work but I just want to get the config-register right. You can't even tell the router to boot from a tftp server because the router ignores that config-register value. The boot rom is 11.X series. I was wondering if upgrading the rom would fix this problem.

If anyone can shed some light on this that would be great.



Re: 2600 config register issue in both Rommon and IOS

change your speed on the console to 9600 this should fix your problem

VIP Purple

Re: 2600 config register issue in both Rommon and IOS


your conole linespeed is set to 115200 instead of 9600. The console port speed is set with the higher bits. If you change this back to 9600 you should be able to set the register to 0x2xxx values.

Download Boson's Config Register Calculator free at, it is quite a nice utility, follow this link:



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