Research on double vlan scheme in ethernet network

With the development of Ethernet in the MAN(Metro Access Network).There is a big limit to isolate and identify the user with 802.1Q VLAN.Because of the VLAN tag which is defined in IEEE 802.1Q is only 12 bits, and can represent 4K VLAN. It is too less to identify the plenty of users. So double VLAN or QinQ is developed.This paper discuss the double vlan scheme in ethernet network.A flexible method is demonstrated in the end