| VPLS(Virtual Private LAN Service) could connect cross-domain virtual private network users through the operator's network. The connection effect just like within the same LAN.Through the complex processing to routing information, MPLS L3VPN solved the problem about the share of routing space in different VPN; By learning the private network routing information of the VPN users, MPLS L3VPN implemented the multi-point transmission. Its large number of network configuration, high-performance edge routers requirements and complex network routing maintenance increased the operators and VPN users'burden significantly. VPLS belongs to the MPLS L2VPN technology, doesn't need to consider the routing overlapping problem in different VPN. It achieves cross-domain VPN user's data transmission simply by learning about the MAC address and establishing PW between PE devices, VPLS reduces the establishment and maintenance costs of VPN networks.This paper firstly describes the development of VPN network, and then make detailed introduction to the MPLS VPN technology. Following three points of VPLS are the main research questions of the full-text.1. Through the study of existing relevant VPLS agreements, realize the PW establishment and maintenance of VPLS network in LDP signaling protocol mode, realized the packet encapsulation of the two-layer packages in different ways for different VPN user access mode, realized the involving of MAC address learning mechanism and aging mechanisms into the PE device.2. In order to achieve point to multi-point data transmission under the VPLS network, it requires to establish a fully connection in network. To achieve this effect, the PW number and PE devices number must be into square in the VPLS network, and it will take up a lot of network resources. This paper will make use of the VPLS network layer management, it means isolate the access function and connect function of PE device into the different two PE devices.The mechanism of that PE devices accessed by user only connect with a single PE device accessed by public network, reduces the PW number in VPLS network, thus to further reduce the network overhead.3. In the layering VPLS network, due to PE devices accessed by user only connect with a single PE device accessed by public network, if the link between the two devices have problems, it will cause the user with the entire VPLS network isolation. In order to reduce risk, the two devices will build a redundant connection link, when the main link has faults, the backup link will complete data transmission. To be able to switch the failure link to backup link as soon as possible, this paper suggests one effective BFD detection mechanism. The establishment of this BFD detection mechanism is on the base of the LSP Ping. It will use the efficient data plane connectivity testing feature of BFD to complete the PW link connectivity testing between devices. Once the link has problem, this BFD detection mechanism will notify the system to switch to the alternate link to go on data transmission. |
