VRFs, or VPN Routing and Forwarding instances, are most commonly associated with MPLS service providers. In such networks, MPLS encapsulation is used to isolate individual customers’ traffic and an independent routing table (VRF) is maintained for each customer. Most often, MP-BGP is employed to facilitate complex redistribution schemes to import and export routes to and from VRFs to provide Internet connectivity.
However, VRF configuration isn’t at all dependent on MPLS (the two components just work well together). In Cisco terminology, deployment of VRFs without MPLS is known as VRF lite, and this article discusses a scenario where such a solution could come in handy.
Assume the topology illustrated below is a network owned by an enterprise. As you would expect, normal company traffic must pass through the firewall so that company policy can be enforced. However, this a secondary Internet connection has been added to this network: an unrestricted ADSL circuit designated for guests visiting the company campus. The 10.0.0.0/16 network is used for trusted traffic, and 192.168.0.0/16 is used for guest traffic.