Layer-2 multicast traffic is typically transported in the overlay. In the VXLAN BGP EVPN fabric, Layer-2 multicast refers to the use of IP multicast technology for transporting multicast traffic in a Layer-2 switching environment.
Layer-2 multicast follows the same semantic as general Broadcast, Unknown Unicast, and Multicast (BUM) traffic. On Cisco Nexus 7000 Series and Cisco Nexus 9000 Series switches, IGMP snooping is used to facilitate Layer-2 multicast forwarding in the fabric.
This chapter only explains Layer-2 multicast. Multicast routing, used for transporting Layer-3 multicast traffic, is explained in the Multicast Routing in the VXLAN Underlay section, IP Fabric Underlay chapter.