VRF route leaking: time to get a little more social!

Virtual Routing and Forwarding (VRF) is a ubiquitous concept in networking, first introduced in the late 1990s as the control and data plane mechanism to provide traffic isolation at layer 3 over a shared network infrastructure. VRF for Linux is an excellent blog that describes the technology behind VRFs, especially as it pertains to the Linux kernel. With the introduction of support for leaking of routes, VRFs get to enjoy their isolation while also having the nous to mix and mingle.

Wait, aren’t VRFs meant to be completely isolated?

You have a valid question there. That was certainly the initial use case for VRFs. Each VRF was intended to represent a customer of a service provider and isolation was a fundamental tenet. Each VRF had its own routing protocol sessions and IPv4 and IPv6 routing tables and route computation as well as packet forwarding was independent from other VRFs. All communication stayed within the VRF other than specific scenarios such as reaching the Internet. Hershey’s wouldn’t want to get too chatty with Lindt, right? No, VRFs weren’t meant to be gregarious.

As VRFs moved outside the realm of the service provider and started finding application elsewhere, such as in the Continue reading