| Because of Ethernet' advantages of simple, easy to use, inexpensive etc., it has been dominant in the local area networks (LAN). With 1GE/10GE Ethernet's widespread application and the increasing of Ethernet application in the Carrier-class network, Ethernet' scalability, reliability, security and manageability are required even higher. However, due to the reliability and stability of the LAN itself, the traditional Ethernet for the LAN has not been established the function of Operation, Administration, and Maintenance (OAM) in the early design, so the lack of OAM function has become the biggest obstacle when the Ethernet joins in metro and wide area networks, Ethernet OAM functions is a key technology which must be solved in this course. With the increasing requirements to network node device, each big network equipment manufacturer produces high-level equitments by extensivly using network processors (NP) with excellent high-speed processing ability and flexible programming ability and so on one after another. These high-level network equipments can achieve OAM function and get better network management by means of merging hardware and software. Therefore, the implementation of the function of Ethernet OAM through network processor becomes a hot issue.This article has been carried out basing on a pre-research project of some communication company which is about "research and implementation of NP-based high-performance router". The author participated in the entire process of the project development, from the overall design, writing detailed design documents, writing code of some modules, testing the system to writing predictable report. Through the project study and development, the author has deeply researched on the routing system and the NP technology, and then completed the design, implementation, testing and analysis of Ethernet OAM on this Ethernet device. Through the analysis of the characteristics of Ethernet OAM technology and the advantages of network processor comparing with general-purpose processor and ASIC chip, this article explains clearly the benefits to carry out OAM functions on the network processor. According to the system structure of NP-based router, this article brings forward a kind of scheme of hybridizing packets processing of NP and control CPU to handle and forward OAM packets.Firstly, a variety of Ethernet OAM protocols are compared and analyzed. And then the related theories, realization principles, message format of OAM technology based on the protocol IEEE 802.lag are analyzed in detail, and the functionality of 802.lag agreement is improved by protocol integration. Secondly, this article studies the system structure, focusing on NP modules of the router' line card and establishes the theoretical basis and development environment of the design. And according to the high-speed data forwarding performance and layered architecture features of NP, the article gives the OAM protocol' module partition, dividing the OAM function' software into NP microcode software and control processor software. Finally, the article carries out a theoretical analysis of the functions and performance of this designed system, and then tests and verifies them in the actual environment. The comparison of experiment result with theoretical description shows that NP-based network equipment has obvious advantages than other general-purpose processors in the implementation of OAM functions. |
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