While working on some older CCNP labs recently I needed to get rid of the frame relay that was used in the various labs since it’s no longer being used and is not supported in EVE-NG. I originally connected everything via a generic cloud and used ethernet interfaces since that is the only type Eve will support to the cloud. While this worked okay I did not like the direct connectivity I was seeing between the routers as it seemed like the DMVPN tunnel I was building was pointless.
Then I decided to use EBGP as the Underlay for the DMVPN Overlay. I choose a very simple implementation where the hub and spokes all connect to the same “ISP”. This makes the scenario much easier since the ISP is just redistributing connected subnets.
Now I’m using DMVPN in the place of Frame Relay for all of my labs and it’s working great. I had never worked with DMVPN before so this was a great lab. Originally it was just a simple OSPF lab that “morphed” into something far more interesting. I’ll post the configuration snippets below in case you are curious.
When I get some extra time I’ll add 2 more ISP routers so that each site it connecting to a different instance of AS1. Then I’ll use iBGP within AS1 to forward the routes accordingly and verify that the tunnel can still be built through various hops as opposed to all meeting on the same AS1 router. This method is a better approximation of a real world scenario.
Another option would be to use EBGP and have each site use a different ISP. Then make the different Autonomous Systems talk to each other to form the tunnel, another very likely real world scenario and one of the whole reasons for using DMVPN.
