According to one aspect, a method includes an Intercloud Fabric Switch (ICS) included in a public cloud and an ICS cluster obtaining a packet, and determining if the packet is obtained from a site-to-site link that links the ICS to an enterprise datacenter. If the packet is obtained from the site-to-site link, it is determined whether the packet is an unknown unicast packet. If the packet is an unknown unicast packet, the packet is dropped, and if not, the packet is provided to an access link that links the ICS to a virtual machine. If the packet is not obtained from the site-to-site link, it is determined whether the packet is obtained from an inter-ICS link that allows the ICS to communicate with the ICS cluster. If the packet is obtained from the inter-ICS link, the packet is dropped if it is an unknown unicast packet.