One embodiment of the present invention provides a switch. The switch includes a virtual network module and a forwarding module. The virtual network module includes a global virtual local area network (VLAN) tag in a packet. The global VLAN tag is mapped to an edge VLAN tag in the packet and is associated with a datacenter domain. The datacenter domain indicates a set of ports associated with a datacenter. The forwarding module identifies an egress edge port for the packet based on the global VLAN tag.