A Study Of Impairment-Aware Routing Technology

In the all-optical network, expensive O/E/O converters are not necessary because optical signals remain in the optical domain from the source node to the destination node. Thus all-optical network can provide great bandwidth with lower cost, and accommodate all types of data services without considering the signal format. However, in the all-optical network, physical impairments are accumulated continuously along the transparent light path, and may eventually cause noise and signal distortion. In order to solve this problem effectively, this paper investigates the novel network architecture capable of impairment-aware routing calculation.There are two topics in this paper. One is the impairment-aware mechanism, and the other is PCE (Path Calculation Element)-based routing calculation. Considering the diversity and complexity of the physical impairments and the feature of all-optical networks, we use OPM (Optical Performance Monitor) to monitor the physical impairment timely in each node of the all-optical network. The SNMP protocol, one of the most common network management protocols by far, is appropriately extended to upload the impairment information from the OPM to the NMS (Network Management System). The corresponding agent and manager have also been designed and implemented by using SNMP++and AGENT++.Another research topic of this paper is the PCE-based routing calculation. Upon a user's request, PCE can be used to calculate the best path based on the known network topology and constraints. Contrary to the traditional control plane-based routing calculation, the PCE framework not only enhances the network scalability, but also relieves the burden of network equipment while a large amount of computing is needed. In this paper, the framework of the PCE has been investigated, including the functional structure, the path calculation procedure and the interface definition and extension of the PCE. Then, a novel impairment-aware path calculation algorithm based on depth-first traversal was proposed and implemented into the PCE. Finally, the algorithm was evaluated by simulation.All-optical network will be the development trend of optical networks in the future. Moreover, there is a growing emphasis on the quality of service, so the study of routing calculation based on impairment-aware has great significance. This paper will lay a solid foundation for the future study.