The best way to know your network equipment, is to have experience working directly with network equipment. I've been an avoid home labber since 2009. Through a lot of craigslist hunting, recycle bin diving,a student loan refund and a slight eBay addiction, I was able to assemble my first full lab rack prior to my first real infrastructure job.
This lab was comprised of primarily Cisco equipment including 1761 Integrated Services Routers, a 3640 Router as a Frame Relay Switch, Catalyst 3550 Layer 3 switches, a couple Catalyst 2950 Layer 2 Switches, and a handful of old 2501 Serial routers. There was also a single Catalyst 5509, as well as a PIX, and a couple Juniper machines.
This lab was based upon a few CCIE level topologies I had researched at the time, as well as INE's reccomendations. Of course, I was only shooting for a CCNA at the time, and hopefully an entry level position. Well, nothing exceeds like excess -- so a CCIE level topolgy was what I wanted to experience building.
The lab was the fast track to understanding. Experience in tha lab push my skills beyond anything I was able to read. From having to find IOS images, ROMMON ruining my life, counterfiet T1/E1 WIC's, realizing that routing was more than a default gateway, and there was more than one subnet mask than 255.255.255.0 - the lab was my first infrastructure position, experience, and love.
Looking back on this huge lab, I see time and money well spent. Looking back on my career, a lab has been a major part of every professional position I have had. My first position had me modeling and architecting national routing at Pavlov Media. My next opportunity at Caterpillar vested the responsibility of innovating in the lab and driving that (sometimes literally) into the field. My home lab experiences taught the self-driven work ethic, and accountability needed to be professionally productive on Day 1. Edovo woudln't have existed without the lab. The lab was as much of a development tool for us as any developer IDE. Thanks to the lab, we were able to model our national WAN, and infrastructure security, prior to raising investment.
I sold all of the pieces of this lab after our first raise at Edovo. I sold everything I had, besides my laptop, some clothes, and my Honda CR-Z, to drive to Philadelphia without a living situation established, to start Jail Education Solutions - which later became Edovo.
My lab now is all virtual with Cisco CSRv, Arista vEOS, and Juniper vMX (more on that later), however I'll always miss the screaming rack and blinking lights that lit the early ways of my career.