Research And Implementation Of Protection Switching Mechanism For PBT Based Ethernet

In recent decade, with the rapid increase of deployment in Wide Area Network (WAN), the Ethernet technology was being improved to face the requirements including high-quality, high-reliability and high-safety for Carrier-class Networks. The Metro Ethernet Forum (MFF) brought the concept of Carrier Ethernet (CE) and dedicated itself to driving the standardization work with a vision making Ethernet a technology can be implemented in Carrier-class Networks. In 2005, MEF defined CE by five attributes: Standardized Services, Scalability, Reliability, Service Management and Quality of Service that distinguish it from familiar LAN based Ethernet. Subsequently, CE technologies emerged, such as PBT, T-MPLS and PVT. As the leading technology, while PBT attracting markets’ attention, how to implement the high-reliability for PBT become an urgent task.PBT was first put forward by the Canadian company Nortel. As a newest technology of Carrier Ethernet, PBT is a temporary standard named GPBT in ITU-T SG15. In IEEE, PBT is considered as a combination of 802.1ah and 802.1Qay. It is said feom the technical characteristics that PBT is a subset of PBB. PBT solved the traffic engineering problems of PBB, and eliminated the broadcast function which lead to MAC flooding and the limit on the size of networks. PBT removed the barriers that restrict expansion of its business, achieved bandwidth reservation, with operational flexibility, security and basic carrier-class management features. Within the continue improvement, PBT has good application prospects.This paper presents a linear protection switching mechanism to provide sub-50ms level protection switching ability for PBT based Ethernet. Base on the analysis of defects of protection technologies for LAN based Ethernet and introduction of CE technologies, this paper presents the details of PBT’s mapping and forwarding mechanism as well as the protection model. The research of the linear protection switching mechanism covers two aspects. In aspect of fault detection, Ethernet Continuity Check function from Y.1731 protocol has been employed. In aspect of protection switching, Ethernet Protection Switching function from G.8031 protocol has been employed to provide two protection architectures,1+1 protection switching and 1:1 protection switching. In the part of the mechanism realization, this paper presents the details including frame format, protocol logic algorithm and explanation for the program functions both in aspect of fault detection and protection switching.In the end of this paper, the test cases and the results of the mechanism have been shown. The analysis of the results and the prospect of the mechanism also have been present in this part.