EVPN in the Data Center

Chapter 5. Routing with Ethernet VPN

Ethernet VPN (EVPN) in the data center is the first Layer 2 (L2) Virtual Private Network (VPN) technology to support comprehensive routing as part of a complete solution. We start with a look at the use cases that motivate the need for EVPN to include routing. This sets the stage for the primary goal of this chapter: to understand the different routing models in EVPN. This helps you, as a network administrator or architect, choose the solution that fits your use case. It also helps you in vendor selection because not all vendors support all models or use cases. Finally, this understanding helps in configuring and troubleshooting routing with EVPN.

The chapter is easier if you understand the basics of routing. I do attempt to do a quick run through the basic logic of routing. But readers unfamiliar with routing will need to walk through this chapter more carefully.

The Case for Routing in EVPN

When virtual L2 network overlays and virtual Layer 3 (L3) network overlays were invented, they coexisted as neighbors. There was a clear fence that separated the two and neither attempted to cross it. This mimicked the nonvirtualized world. Both in the control protocols used and in the packet-forwarding behavior, the two realms differed. In the service provider (SP) world, two sites were connected via either a virtual L2 network or a virtual L3 network. Rarely, if ever, were they connected as both. So, what use cases drive the need for a comprehensive ...