Week 1 Notes

"Stuff I should Have Known Before Ginter Made Me Do The Lab"

How to Reset a Cisco Router Password

• Have Putty or some other terminal program running on port connected to the router console cable
• As router starts to boot send a break signal (Ctrl-Break on Putty)
• This should put the router in ROMMON mode.
• Type confreg 0x2142 This sets a bit in the router to bypass the startup configuration
• Type reset to reboot the router.
• Respond no to all startup questions
• Type enable to get into privileged mode
• Get the startup configuration into memory: copy startup-config running-config
• Enter configuration mode by typing: configure terminal
• Set a password by typing enable secret aSecretPassword
• Put the configuration register back to boot from startup: config-register 0x2102
• Save your password: copy running-config starup-config
• You can now reboot or restart your router.

Reset Startup to default

1. From putty press ctrl-break while router stats booting
2. at rommon prompt type confreg 0x2142
3. at rommon prompt type reset to restart the router
4. When the router offers to go through setup type no
5. at Router> prompt type enable to enter the privileged enable mode.
6. at Router# prompt type copy running-config startup-config
7. at Router# prompt type config t
8. at the config prompt type config-register 0x2102
9. type exit to leave config mode
10. type write memory to create a configuration
11. type reload to reload

Reset Cisco 3750 Password

• Source: Reset Pswd

1. configure terminal

• Attach a terminal or PC with terminal emulation (for example, Hyper Terminal) to the console port of the switch.
• Use these terminal settings:
  • Bits per second (baud): 9600
  • Data bits: 8
  • Parity: None
  • Stop bits: 1
  • Flow Control: Xon/Xoff

2. Unplug Switch Power
3. Hold down the mode button located on the left side of the front panel, while you reconnect the power cable to the switch.
4. Release the Mode button after approximately 15 seconds when the SYST LED turns solid green. When you release the Mode button, the SYST LED blinks green.

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Week 1 Slides - IP Addressing Review

• OSI Model
• Network ID -> Host ID -> MAC Address
• Three types of communication in an IPv4 Network
  • Unicast: The process of sending a packet from one host to an individual host.
  • Broadcast: The process of sending a packet from one host to all hosts in the network.
  • Multicast: The process of sending a packet from one host to a selected group of hosts.
    • IP range 224.0.0.0 to 239.255.255.255 reserved for multicast
    • Multicast uses UDP