Network Discovery: Manual vs automated

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.

  • Thanks for the reply. It seems like you've used quite a few products. Have you looked into Auvik or Net Brain?

    Regards,

    Keith

  • I was fortunate to be part of a recent deployment.  We used a combination of manual and automatic discovery and verified they matched as we proceeded.

  • I'd LOVE a reliable automated discovery and mapping tool--one that tied directly to Visio.  But the practical truth is that, while I've really enjoyed some of the mapping tools I've used, many are limited, many provide too much information, and nothing I've tried has met my needs so completely as manually discovering and documenting.  And that's disappointing; something should have already been built and marketed and sold that does the job the way I need it.  3Com's Transcend flavor of HP OpenView was great, but could easily miss something that was not a 3Com product.  Visio's earlier discovery tool was removed from the market, sadly.  HP OpenView itself was a nightmare to learn, deploy, filter, and maintain.  Nortel's Enterprise Switch Manager was an EXCELLENT tool, but wouldn't show you if a Cisco AP was plugged into a switch--it was very Nortel-centric.  CiscoWorks didn't.  And NTM provides too much information for segments and VLAN's where I may only need/want physical links.  Filtering out the unwanted NTM items never worked the way I needed, despite countless hours working with Tech Support.  I'm still looking for the product that does what I need, no more, no less.

  • I just started a job where they have me learning SolarWind NPM and the learning curve for it is pretty nice. However it is pretty dauting looking at the system we have already configured and i've been confused with where everything is located. I like being part of the beginning of things just so I know whats going on, so I would defintely have loved to do manual discovery had I been the one to implement it emoticons_silly.png

  • I agree on the descriptions... they are never kept up!  Constantly evolving and when you think you are caught up and all is perfect, think again!

    I was out for 4 months once and noone kept anything up and now it is all back to groud zero and it makes it hard to even want to recreate when you are the only one that cares!

    Just saying....

    LOL @ SNMP Dictionary Attack from cahunt!

Thwack - Symbolize TM, R, and C