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I know, VRFs are meant to create a seperation on layer3. There are certain ways to "break" thru a vrf in a sense with things like:

  • Tunnel interfaces
  • IP helper
  • NetFlow

But is there a way where i can let traffic between 2 interfaces that are assigned to different VRFs flow freely, like they would be in the same VRF? The only thing i could find was route-leaking, but as far as i understand it, it just lets you collect routing table entries from differnt VRFs and put them together into one VRF.

Appendix: I read and tested multiple solutions that would allow me to let 2 interfaces assigned to different VRFs talk to each other. Im just posting the different ways just in case someone else stumbles upon this thread in the future:

  • VRF Route leaking (BGPVPNv4) - requires BGP, most famous example, lots of tuning possibilities
  • Static routing - does not work directly from VRFa to VRFb, uses global VRF as a halt in between VRFs.
  • VRF Receive - does only work in one direction, from a VRF interface into the global VRF, return path needs to be set via static route. Only works for networks that are directly attached to the interface
  • Route Replication with EVN (Easy Virtual Network) - this requires a new syntax of configuring VRFs, there is a command that lets you migrate from old syntax to new one, lets you synch complete routing table between VRFs, easy configuration, lots of filtering possibilities.
  • VRF traversal via PBR (Policy based routing) - easy to understand configuration, is not involved in routing tables or protocols at all, lots of filtering (source networks, packet size, and so on) options, does only affect traffic that is entering the router from outside. Router originating traffic may not take the desired path

For me, the EVN option is the best one.

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Each VRF contains its own routing table and which is separate from the global table.

You need to use route-map/prefix list that would inject the routes to inform each table where the other exists.

Think of the each VRF as a separate router. How would you use achieve this if they were physically sperate routers? A: running a routing protocol (Static vs AS)

So it comes down to what routing protocols you are using.

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