Kostis Netzwerkberatung
Konstantinos Kostis
Talstr. 25, D-63322 Rödermark
Tel. +49 6074 881056, FAX 881058
kosta@kostis.net, http://www.kostis.net/
You may use this information free of charge at your own risk
V1.02 2002-06-01
I've seen this numerous times. Customers tell you they have a spare Cisco router and ask you to configure it. "Sure, no problem", you say and think but then their router comes without a console cable, nobody knows any passwords and/or who may have configured it, so that leaves you with only one option: recover.
To recover a Cisco router, connect a terminal or PC with terminal emulation serial port such as COM1: to Cisco console (RJ-45) port. Communication parameters are 9600-8-n-1-none.
Right after you turn on your router power send Break (real DEC VT terminal emulations have F5 for that).
Depending on the Cisco model a simple prompt shows up.
User break detected at location 0x2006718
rommon 1 > confreg 0x2142
rommon 2 > i
Abort at 0x3171892 (PC)
>o/r 0x2142
>i
This will tell your Cisco to ignore its startup-config file from now on and then reboots.
After reboot, now without any configuration, type:
| > enable | enable mode | |
| # erase startup-config | erase old configuration including passwords | |
| # configure terminal | prepare changes for register value | |
| # config-register 0x2102 | recover original register value | |
| # exit | return to command mode | |
| # reload | do not save changes if any |
Yes, it is that easy. ;)