This feature is used to connect a Layer 3 EVPN VXLAN network to an Adaptive Virtual Topology (AVT) WAN network using dynamic path selection (DPS) tunnels. One or a pair of WAN routers are configured to serve as the VXLAN gateway. On the control plane, the configured VXLAN gateway handles EVPN IP-PREFIX route exchanges between the VXLAN network and the WAN network. On the data plane, the configured VXLAN gateway decapsulates the VXLAN packets received from the VXLAN network and encapsulates them into the DPS tunnels and sends them to the AVT WAN network. 

Today in any WAN deployment, customers are required to configure path metrics in load balance policy to program a set of best paths in dataplane. Path metrics are multi-dimensional, it include loss, latency, jitter, and load of path. It is not very intuitive to come up with exact values for these metrics as they are highly dependent on the type of application and geographical locations of routers. Also these path metrics keep changing and except for a few apps that require strict max characteristics on latency, jitter or loss, the other apps are able to tolerate variances in metrics.