In the VLAN aggregation technology, multiple Sub-VLANs are used to isolate the wide recruitment area, and these Sub-VLANs are aggregated into a logical Super-VLAN. A company divides different departments into different Sub-VLANs, because Sub-VLANs It not only includes physical connection, but also can establish a three-layer VL ANIF interface, which can directly communicate with the external network at three-layer.