A method for establishing a broadcast domain in a Layer 2 Virtual Private Network, L2VPN, comprising a Provider Edge, PE, and a Customer Edge, CE, a connection between the PE and the CE being an Attachment Circuit, AC, and a connection between the PE and the PE being a Pseudo Wire, PW, the method comprising the steps of: when a packet is received from the AC, finding out a Virtual Bridge Domain Index, VBD ID, of the packet according to an AC attribute table; in the case where it cannot be acquired an exit for the packet from a forwarding table according to the VBD ID and a destination Media Access Control, MAC, address of the packet, acquiring an exit corresponding to the Virtual Bridge Domain, VBD, from a VBD table according to the VBD ID, and sending the packet out after encapsulating it based on an encapsulation rule, the VBD ID being the index set for each VBD and the VBD being obtained by dividing each VPN into one or more VBD; when a packet is received from the PW, the packet being encapsulated by using the VBD ID based on an encapsulation rule, in the case where it cannot be acquired an exit for the packet from the forwarding table according to the VBD ID encapsulated in the packet and the destination MAC address of the packet, acquiring the exit corresponding to the VBD from the VBD table according to the VBD ID, and sending the packet out after de-encapsulating it based on a de-encapsulation rule, wherein the AC attribute table is a table composed of information of an AC entrance on the PE, and the VBD ID and a VPN ID corresponding to the AC entrance, the information of the AC entrance being information of logical interface defined for each AC connection in the PE, and wherein the VBD table is a form composed of one or more VBD records, each VBD record being marked by the VBD ID and each VBD record comprising information of all AC and PW exits currently assigned to the VBD by the PE. when a packet is received from the AC, finding out a Virtual Bridge Domain Index, VBD ID, of the packet according to an AC attribute table; in the case where it cannot be acquired an exit for the packet from a forwarding table according to the VBD ID and a destination Media Access Control, MAC, address of the packet, acquiring an exit corresponding to the Virtual Bridge Domain, VBD, from a VBD table according to the VBD ID, and sending the packet out after encapsulating it based on an encapsulation rule, the VBD ID being the index set for each VBD and the VBD being obtained by dividing each VPN into one or more VBD; when a packet is received from the PW, the packet being encapsulated by using the VBD ID based on an encapsulation rule, in the case where it cannot be acquired an exit for the packet from the forwarding table according to the VBD ID encapsulated in the packet and the destination MAC address of the packet, acquiring the exit corresponding to the VBD from the VBD table according to the VBD ID, and sending the packet out after de-encapsulating it based on a de-encapsulation rule, wherein the AC attribute table is a table composed of information of an AC entrance on the PE, and the VBD ID and a VPN ID corresponding to the AC entrance, the information of the AC entrance being information of logical interface defined for each AC connection in the PE, and wherein the VBD table is a form composed of one or more VBD records, each VBD record being marked by the VBD ID and each VBD record comprising information of all AC and PW exits currently assigned to the VBD by the PE.