The following figure shows a sample topology using Multicast.

The Edge Service Gateway uplink interface is connected to the physical infrastructure through the vSphere distributed switch. The Edge Service Gateway internal interface is connected to a logical router through a logical transit switch. The logical router's default gateway is the ESG's internal interface IP address (192.168.10.1). The router ID is the logical router's uplink interface---in other words, the IP address that faces the ESG (192.168.10.2). In this topology, Multicast traffic is replicated in an optimal way, across subnets, between sources and receivers inside or outside the NSX domain.