Key Technique Research Of High Redundancy For Broadband Remote Access Server

With the development of the information industry, and the growing popularity of home informationization, Internet has become a very important part in people’s daily life. The reliability of user access network plays a key part of the reliability in operators’ networks, which directly determines that if subscribers could always access the network successfully.This paper studies the key problems in redundancy standby technology with high reliability for the core network element in broadband access network, Broadband Remote Access Server (BRAS). This paper analyzes the status of BRAS in the networks, hardware and software structure, the possible failure points, and illustrates the necessity to research and develop the redundancy technology for BRAS. By summarizing and analyzing the existing redundancy technology based on link redundancy, this paper proposes a high reliability redundancy technology for BRAS, and tries to deployment in commercial networks.The main contents of this paper are as follows:(1) This paper summarizes and analyses the existing redundancy technology based on link bundling, the delayed response mechanism of the offer packet in PPPoE and DHCP protocol, the dual-route technology for static IP address users, and proposes a high reliability redundancy technology that protect the subscribe keeps online with its original IP address and services while the BRAS fails or the links of the BRAS fails.(2) This paper describes the implementation details of the high reliability redundancy technology, including the auto-election mechanism of the main and backup BRAS, the fault detection and protocol interaction, the traffic redirection method, and the rollback method while fault recovery. Especially, this paper proposes for different method for traffic redirection, compares the advantages and disadvantages.(3) This paper describes the deployment of this technology in commercial networks, and summarizes the experimental case.