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IOS 12.3(14)T5 and 831 routers

We recently upgraded an 831 router to IOS 12.3(14)T5. I consoled into the router via my PC/Hyperterminal to tftp the startup config. I copied the startup to the router via tftp, reloaded the router and even before I could get to the logon prompt, I lost connection in hyperterminal. The only way at that point I can get into the router is via dialup. I went ahead and erased the config, reloaded and was able to console in again via the PC. I went ahead and copied the config again but this time I removed all exec-timeouts from the console, aux and vty lines. I reloaded and same issue occurred. Ever since we've upgraded the IOS this problem occurs. A few questions: Is there an issue with 831's and IOS 12.3(14)T5 like this one? If so, is there a workaround? Can I downgrade the IOS to a lower version like 12.3(11)T5 and not cause any issues to the router? Thanks for the help.



Why don't you just erase your config and then copy and past the one you want to upload to it. At that point then save the config send it to your tftp server and try tftp'ing it back.

It might be there is something in your tftp'd version of your config that the new ios doesn't like. Call it what you want could be a bug.



What's weird is that I flashed the router with the the previous flash version we used 12.3(11)T5 and it was working fine. A colleague of mine called Cisco support and they said there was some type of speed mismatch with the Aux port and that's why I was getting disconnected but how is it that when I went back to the older IOS that it worked fine. Weird.


It's because the default baud rate for the line con 0, on the old IOS is 9600 and since this is the default it doesn't show up in the running-conf.

Now when you loaded the new IOS it propably had another default baud rate on the line con 0, maybe 115200.

If you had made a "sh line con 0" on the router after having upgraded, you would have seen what the default value was, and you could have changed it back to 9600, like so.

line con 0

speed 9600


I'll try that the next time. Thanks!


I tried this but nothing changed. I noticed however, when I copied and pasted the config in, the console commands were copied but not the aux and vty commands. I reloaded the router and manually typed in the commands for those lines and then once again I could not console in after reloading the router. It seems the problem is with the commands with the aux port. Any other ideas?

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