After learning how to configure IPsec on devices running Cisco IOS, we are now going to conduct a small experiment by setting up Multi-VRF (Virtual Routing and Forwarding) IP technology. This method is very useful in scenarios where you need to create multiple routing tables on a single router. First, we will provide a detailed introduction to what VRF is, and then we will explain how to perform the specific configuration.
What is Multi-VRF?
For users who want to configure multiple routing tables on a router, VRF is an excellent choice. Its function is to isolate routing and control customer traffic on the same device. However, some might prefer using sub-interfaces or different physical interfaces to segment customers and utilize access control list filtering to achieve traffic separation. Indeed, this is certainly a viable method; but, if for some reason you need to handle overlapping customer addresses, it faces a significant problem. With VRF, the router can achieve the effect of assigning the same IP address to two different interfaces simultaneously.
Recently, I encountered such a situation. During a training session, I set up a lab environment consisting of eight separate sections, all using the same topology and the same addresses. The basic topology is shown in Figure A:
