Techniques are provided for designating, in an overlay transport virtualization (OTV) network connected to a data center, an edge device to act as a backup authoritative edge device (BAED) for an authoritative edge device (AED) for multicast packet encapsulation and forwarding. Data traffic associated with a given virtual local area network (VLAN) may be detected from a multicast source in the data center addressed to recipients in a site group. A mapping may be generated between the site group and a core data group in the OTV network for traffic from the multicast source. Advertisements may be sent of the mapping to edge devices in another data center across the OTV network. A similar configuration is presented for a BAED for inbound multicast traffic to a data center.