Optimized EVPN-VXLAN DCI with enhanced OISM and an IPv6 underlay

You can configure enhanced optimized intersubnet multicast (OISM) and seamless Data Center Interconnect (DCI) with EVPN-VXLAN instances on an IPv6 underlay. In EVPN-VXLAN DCI fabrics with enhanced OISM and an IPv6 underlay, DCI gateway (iGW) devices send EVPN Type 6 Selective Multicast Ethernet Tag (SMET) routes to remote iGW devices when hosts subscribe to multicast groups. iGW devices in the source data center selectively forward multicast traffic for a group across the DCI only if the remote data center has receivers subscribed to that group. Previously, the iGW devices always flooded multicast traffic across the interconnection even when the remote data center had no subscribed receivers.