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Friday, June 20, 2014

Starting my Journey - Bonus: Resetting Cisco Routers/Switches to Factory

I've been eagerly watching the CBT Nuggets CCENT training videos, and so far I'm loving it. TCP/IP networking is like fricking magic! It's complicated, but it makes a lot of sense. I have been looking at Wireshark captures and already found some interesting things occuring on the network. Did you know that if Dropbox is installed on a computer, it sends out ARP broadcasts every 30 seconds looking for other DropBox installations? It's called "Dropbox LAN Sync Discovery Protocol".

In other fun news, in VMware Workstation I successfully go Windows 3.11 for Workgroups, Windows 95, and Windows 98 talking to each other over TCP. Just because. :)

After some more introspection, I have decided that it's very good that I'm getting into networking with the CCENT. I might even go farther than that. When you get right down to it, IT is all about the DATA. Up to this point (and I don't see this changing soon - I'm just branching out), I have dealt mainly with presenting the data to the employees. Email, file shares, whatever. But I got to thinking: what are the core things that need to be done with data? Data needs to be:

  • Copied (backed up)
  • Secured (ensure CIA: confidentiality, integrity, accessibility)
  • Transmitted (Networking)
  • Converted into information (Monitoring, reporting, database mining)
  • Stored (SANs, DAS, etc)

I figure, the closer I get to the core functions of the DATA, the better my job prospects will be, in my opinion.

Work had some old Cisco gear laying around that I can use, so I now have at my disposal:

1 Cisco Catalyst 3550 switch
1 Cisco 2600 router with 2x WIC 1DSU-T1 cards (ports look like cat5/6 - do they take something special or can I plug an ethernet cable in there?)
2 Cisco 1841 routers each with 1 WIC 1DSU-T1 V2 card.

I managed to hunt down instructions on how to reset them and have done the needful. Here are the instructions I collated and tested (as much for my reference as yours!):

Resetting the Cisco 1841 and 2600 routers to factory:

  1. Make sure router is powered off
  2. Connect console cable, and bring up putty in the correct COM port
  3. Boot router
  4. Send the break command (right-click on the window bar and choose special command->break)
  5. type confreg 0x2142
  6. type reset
  7. Once the router reboots (say no to initial config dialog), enter enable mode, then type reload
  8. Once the router reboots (say no to initial config dialog), enable, and conf t
  9. type config-register 0x2102
  10. type exit to get back to enable mode
  11. type write memory
  12. type reload

Resetting the Cisco Catalyst 3550 to factory:

  1. Connect the console cable to the switch and start your terminal program (HyperTerminal/Secure CRT). Console port settings are 9600,8,N,1
  2. Hold the MODE button (on the front of the switch) while you power on the switch.
  3. Hold the MODE button for a few seconds until you the System light stop flashing.
  4. At this point, the switch should be in ROMmon mode. 
  5. From ROMmon mode, type: flash_initStep 
  6. From ROMmon mode, type: delete flash:config.textStep 
  7. From ROMmon mode, type: boot


  1. Let's be honest. The networking side is the more elite area to be knowledgeable in, too. It's quite complex shit sometimes, but once you get the hang of it (as in you use it consistently), the sky's the limit on where you can go within that field. And holy acronyms batman, I don't know any other area in the IT field that has more of 'em than networking.

    Looking forward to more posts regarding your journey towards the CCENT!

  2. In general, I agree. I think storage and security might give it a run for its money, though! Also, holy acronyms indeed!