3. Source S1 in VLAN 10 starts streaming data. VTEP 1 forwards the multicast packets to all other VTEPs that have receivers. 4. Layer 2 multicast packets are encapsulated with L2VNI that corresponds to VLAN 10 and are forwarded through the overlay to VTEP 2. 5. On VTEP 2, the L2VNI encapsulated data packets are decapsulated and forwarded to the port where receiver R3 is connected. Optimized Layer 2 Overlay Multicast Interworking in BGP EVPN VXLAN Fabric VTEPs in the EVPN VXLAN network forward traffic to each other through the VXLAN gateways. An EVPN VXLAN Centralized Gateway (CGW) VTEP performs the Layer 3 gateway function for all the Layer 2 VNIs.
All the other VTEPs in the network perform only bridging. For information on CGW, see “Configuring EVPN VXLAN Integrated Routing and Bridging”. Optimized Layer 2 Multicast across Layer 2 Overlays In an EVPN VXLAN fabric, a CGW performs routing for the inter-L2VNI Layer 2 multicast traffic. In this case, the sender and receiver, both could be on the same VTEP or they could be on different VTEPs within the EVPN VXLAN fabric. Source and Receiver on Different VLANs, connected to Different Layer 2 VTEPs Figure 2:
Topology to show Layer 2 Overlay Multicast Traffic between Different VLANs Configuring Optimized Layer 2 Overlay Multicast Optimized Layer 2 Overlay Multicast Interworking in BGP EVPN VXLAN Fabric Configuring Optimized Layer 2 Overlay Multicast 3