Research And Implementation Of Ethernet OAM In Distributed Three-Tier Switch

At the beginning, Ethernet was designed for the LAN. Because the LAN itself has a high reliability and high stability, so OAM (Operation、Administration and Maintenanee) mechanism of Ethernet was not built. Compared to LAN, the link length and the coverage of the MAN and WAN are rapidly expanding. Because there are many of different users that require sophisticated needs in the MAN and WAN, so it needs different operators to work together to provide end-to-end business. There are many requests about security, scalability, manageability of the Ethernet. Hence the lack of effective management and maintenance mechanism of the Ethernet, it has become a serious obstacle in the MAN and WAN applications. Distributed three-tier switch due to the high forwarding rate, high reliability, have been widely used in the enterprise network and Telecom operators network. Therefore, implementation of ethernet OAM in distributed three-tier switch is becoming focus in the use of enterprise and telecom.This article has been carried out basing on a research project "the implementation of IEEE802.lag protocol" that belongs to some communication company. The author participated in the entire process of the project development, from requirements analysis, preliminary design, coding, unit testing, system testing, to project acceptance.The article analyzes about principle of ethernet two-tier and three-tier exchange, the differences of three-tier switch and edge router, the advantage of distributed forwarding system to centralized forwarding system and technical features of ethernet OAM based on the protocol IEEE802.1ag, which shows the advantage of implementation of ethernet OAM on the distributed three-tier switch. Based on distributed system, the article brings forward a kind of scheme using the three-tier forward chip ASIC (Application Specific Integrated Circuit) and CPU to realize packet forwarding. According to device of some communication company, the scheme is designed and realizing, having the feateure of high reliability, high forwarding rate.Firstly, it is introduced about the development background of ethernet OAM, research status and the agreement of related protocols. The article has been carried out for research and implementation basing on the IEEE802.1ag CFD (Connectivity Fault Detect) protocal. Secondly, this article introduce the hardware and software architecture for a distributed switch what establishes the theoretical basis and development environment of the design. Then, based on the CFD protocol, this article introduces the the basic concepts of Ethernet OAM, protocol functions and message format. After that, through analyzing the differences of principle between distributed three-tier forwarding system and centralized two-tier forwarding system, the article shows the advantage of implementation of ethernet OAM on the distributed three-tier switch. The article gives a overall design to CFD module based on distributed system through analyzing needs of protocol CFD. Finally, the article gives a plan that describes detailed design and implementation for CFD module based on distributed system. The author is fully responsible for design, implementation and test of the process of startup and initialization, configuration processing and protocol processing sub-module.