Device Management

4 days until Christmas 👍, and I 'm trying to get a few lessons in before the Chapman Family party today. Putting a little Grizz coffee in the bear!

Router Memory

1. ROM - powering on loads from ROM first and performs (a) Power On Self Test (POST)- checking for any problems with the hardware, the (b) Loads Bootstrap- looks in Flask for IOS software to load, if no IOS present, the device will boot to the ROMMOM prompt and the image could be pulled from TFTP or a USB
2. Flash Memory - device will load the first IOS image found by default, you can override this with the (config t) boot system......
3. NVRAM (Non-Volatile RAM) - this is where the startup-config file is located; if not present the device will load the Start Wizard
4. RAM - working memory of the device; IOS from Flash and the Startup-config from NV-RAM are loaded into the RAM at startup

Factory Reset

Router> write erase  this deletes the NVRAM -->  the startup-config

Password Recovery 

Config-Register  is used to change the way the device boots

0x2102: boots normally (default)

0x2120: boot into rommon

0x2142: ignore contents of NVRAM (startup-config)

(config t) config-register 0x2142

1. Reboot device, press Ctrl-Break at power on to break into rommon
2. rommon> confreg 0x2142 (this will ignore startup-config on boot)
3. rommon> reset (this will reload device with no config, however, the original config is still in NVRAM with the unknown enable secret password)
4. Type "no" to bypass the setup wizard
5. Enter "enable" mode - device will not prompt for enable secret as there is not one in the running configuration.
6. router# copy startup-config running-config - NOTE: you are already in enable mode :-)
7. router (config t)# enable secret  xxxxxxx (Enter new enable secret to over right old one)
8. router (config t)# config-register 0x2102 (device will boot normally at next restart)
9. router# copy running-config startup-config 

Backing up System Image and Config

• router# copy flash tftp   (prompted for file name of IOS image in flash to copy, then address of tftp server)
• router# copy running-config tftp  (prompted to give new name to running-config, and address of tftp server)
• Note: if you copy anything to running-config…it will just merge with running-config
• Back up config to flash and restore -
• router# copy running-config flash  (now we have a backup)
• router# write erase    (delete startup-config)
• router# copy flash startup-config
• router# reload

Upgrade IOS

1. Download new IOS from Cisco to TFTP
2. router# copy tftp to flash
3. The old IOS could be deleted, and at reload the new IOS is the only file to load
4. To keep the old IOS at a backup, must change the boot system
5. router (config t)# boot system flash: (file name in flash)
6. router# copy running-config startup-config
7. router#reload

IOS Licensing

1. After purchasing a license to unlock a feature on your device, Cisco will provide a Product Activation Key (PAC).
2. Enter the PAC at (cisco.com/go/license) with the UDI (Unique Device Identifier) to create the license file.  Note: license tied to device
3. Load the file to Flash, then install

• Router (config t) license install flash: (file name)
• Router# show license  (note: to display UDI - r1#show License udi)