Research On The Multi-Failure Protection Algorithm Of Automatic Switched Optical Networks

With development of the optical transport technology, Automatic Switched Optical Network(ASON) is becoming the key to the next generation optical network. The mesh based ASON introduces a control plane which provides dynamic resources allocation and automatic connection creation functions, and is adapable to the trend of the next generation networks. However, upon deployment of ASON networks, the self-healing under multi-failure in a complex network environment will become a critical issue requiring extensive researching.This thesis focuses on multi-failure protection machanism of next generation optical network, and reports the research of path-protection technology in ASON. Topics include the dual-link failure path protection algorithm and the multi-failure path protection algorithm considering SRLG constraints. Based on the existing Three-Step-Algorithm(TSA), a novel heuristic algorithm considering tap problem, is proposed to avoid link-failure trap, achieve effective resource utilization and balance traffic load. Based on Active Path First (APF), another heuristic algorithm, called conflict detection protection(CDP), is provided to decrease blocking probability and effectively avoid SRLG trap through iteratively testing SRLG conflict link.To verify the feasibility of the proposed algorithms, the simulator GLASS is used for developing an algorithm simulation platform. Results show that the improved TSA can provide complete dual-link failure protection. Meanwhile, the algorithm can decrease the blocking probability without increasing the complexity. In addition, it's showed that CDP can effectively avoid the trap problems, and give 13% maximum of blocking probability of call lower than APF.