The restoration time is an important network survivability index in large-scale Metropolitan Area Network. The early study indicates that the hierarchical restoration mechanism have lower restoration time, comparing with global restoration. But the restoration time increases rapidly when the restoration scope expands. In this paper, Overlap-extend hierarchical restoration mechanism is proposed to reduce the restoration time, by restricting the restoration in a definite scope. A theory model is established to describe the average restoration time of Overlap-extend mechanism and existing hierarchical restoration mechanism, which can be used to analyse the influencing factors in our mechanism. Simulation result is also presented, which shows that overlap-extend mechanism can observably reduce restoration time, especially in light traffic load.
A network test bed with 100 network simulative nodes is set up. Convergence time experiments and signalling network flow experiments of Automatically Switched Optical Networks using Hierarchical Routing Protocol have been performed on it, and an experiment analysis is given.
Hierarchical routing architecture has been adopted by ASON for scaling purpose, and corresponding changes in both network management structure and management information models result. Based on the discussion of new requirements for ASON management system to support the hierarchical routing infrastructure, an ASON management system is proposed and developed in this paper with new network management information models. Finally, the flexibility of the proposed management system is demonstrated on an ASON testbed with 200 emulated nodes.