MDT in the fabric builds upon the EVPN VTEP auto discovery. After the user configures VLAN to VNI mappings for each leaf, BGP Inclusive Multicast Ethernet Tagged (IMET) routes are initiated and distributed within the fabric. Each node that participates in a flood domain initiates an IMET or EVPN Type 3 route. Any node that receives an IMET route, establishes a VXLAN tunnel to the remote destination if it belongs to the same domain.
The following figure shows an overview of VTEP Auto-discovery. Node A initiates an IMET route signal in the network. Since nodes B and D are part of the same flooding domain, establish VXLAN tunnels with node A. Similarly, the IMET route signals initiated by nodes B and D form VXLAN tunnels with other leaf nodes.
The following figure shows an overview of unicast VXLAN tunnel establishment. Each leaf creates a tunnel with node A after receiving the IMET route. Eventually, a full mesh of tunnels from each of the nodes participating in VLAN 10, using the same VNI are established.
