How to load a config file onto a Cisco router

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Plug the blue serial cable [known as a console cable] that came with your Cisco router into the console port on the router and the serial port in your computer. Start up your favourite terminal program (such as HyperTerminal - select "Direct to COMx"). The correct terminal settings are 9600 baud, 8 data bits, no parity, 1 stop bit, and I usually choose hardware flow control. For reliability, you also need to set the line delay to 100ms (File/Properties/Settings/ASCII Setup).

If the router is on, switch it off. Now turn the router on. Note that it takes about two minutes for router to complete booting. If the router asks if you want to run the setup wizard, say no. If it asks you if you want to get started tap return a couple of times. If you get nothing within 30 seconds of turning the router on, tap return a few times. If you still get nothing then check your serial connections and parameters.

For safety, lets start by wiping the routers current config. Enter these commands:

erase nvram:
Erasing the nvram filesystem will remove all configuration files! Continue? [confirm] 

Press "y" to erase the routers config. Then enter the below commands. Note that the router may not ask you to save the current config. If it does, make sure you say no - we are trying to wipe the config.

System configuration has been modified. Save? [yes/no]: no 
Proceed with reload? [confirm]

Press "y" to let the router reboot. For those people who have some familiarity with Cisco routers the "erase nvram:" command has superceded the "write erase" and "erase startup-config" commands (these commands all do the same thing).

When the router has completed booting this time it will ask if you want to run the setup wizard.  Say "no". It should eventually tell you to press "return to get started". Tap return a few times. Now we need to go into config mode:

config terminal

Now copy the config you want to load onto the router into the clipboard (hint: CTRL-A then CTRL-C), and paste into HyperTerminal (Edit/Paste To Host). Once it has pasted in, you need to save the config.

copy running-config startup-config

With any luck, your now done!