There is much talk in the IT profession about automation. “Automate all the things” is written in some shape or fashion across a variety of blogs and social media platforms. I even briefly mentioned it in my last Geek Speak post about configuration management. You have read that already... Right?

 

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I get the movement. Why do everything manually, wasting your time on tedious, trivial tasks when you could be working on the newest design for your data center or something better? And even though I could probably consider myself a new age networking professional, there’s still one task I enjoy doing the old-fashioned way: network discovery.

 

Call me crazy, but the task of learning a network for the first time in my opinion is best done manually. There are so many nuances that could be lost if this process is done automatically. Dissecting a network, one device at a time, port by port truly allows the ability to intimately understand the complexities of that network. Here are some tips and tricks that I have learned along the way and also seen other networking professionals speak of when discovering a network for the very first time:

 

  • Start from the Core switch and work your way out (if you don’t know where the Core switch is, start with your default gateway and branch out)
  • Use information like CDP/LLDP, ARP, MAC-addresses, and routing tables to help you navigate
  • NEVER completely trust switch port descriptions or network diagrams. They are almost always not kept up with or updated regularly.
  • Draw out the network as you go using pencil and paper. You will continuously edit this diagram so using pen will hamper you and trying to input this into a program like Microsoft Visio while continuously making changes will make you scream.


What about you all? Do you prefer automated network discovery or would you rather do it manually? Have any tips for either method? I look forward to hearing from you all.