A couple years ago, Ivan Pepelnjak wrote an interesting blog showing how all you need are two top-of-rack switches. Iwan Rahabok followed up on the systems side, with the perspective that 1000 VM per rack is the new minimum.
Now in mid 2017, I'd like to show you how we can fit 2M network routes, 1PB of storage, and over 1000 VM's in a half rack. Don't worry, I included redundancy as well.
Disclaimer: My examples use specific vendor equipment