EVPN-VXLAN DCI multicast with enhanced OISM

We support Ethernet VPN-Virtual Extensible LAN (EVPN-VXLAN) to EVPN-VXLAN seamless Data Center Interconnect (DCI) with enhanced optimized intersubnet multicast (OISM). Without this feature, the DCI gateway devices flood multicast traffic across the interconnecting WAN. Flooding consumes significant WAN bandwidth if your network has many multicast flows or high multicast traffic rates. This feature seamlessly replaces the multicast flooding behavior.