Chapter 1. Introduction to EVPN
A wet California winter and spring had started to make way to sunny summer skies when I was invited to meet with a large financial company. The organization wanted me to critique its data center network design. Its use case revolved around a Layer 3 (L3) network. Clos-based topology was the basic network architecture it had chosen. Everything was done as nicely as I could suggest. No longer did I have to explain why the company had to move away from bridging as the centerpiece of its data center or why Clos networks were a better fit. One more conversion accomplished. I moved on.
As the summer turned to fall, the company approached me again to discuss a new constraint it had to deal with. The enterprise was going to deploy a new storage cluster solution in the network. This solution expected a Layer 2 (L2) connectivity to work. Needless to say, the L2 connectivity had to be across multiple racks. “Dinesh, how do I fit a solution that expects L2 connectivity in a network that has L3 as its foundation?” engineers at the company asked.
Increasingly that fall, I heard the same refrain over and over again. “How do I deploy an application that requires L2 in an L3 network?”
Another group of companies I spoke to were building new data centers and wanted to embrace the new world of white boxes and Clos networks. They had newer applications either like Hadoop or that relied on constucts like containers, so the new world was a great fit. Yet another group ...