Optimal Path Calculation for Multi-ring Based Packet–Optical Transport Networks

Multi-domain optical transport networks are inherently non-interoperable and require integrated orchestration and path provisioning mechanisms at the network-wide level. Moreover, ensuring the network’s survivability is a critical issue. While the MPLS-TP (multi-protocol label switching-transport profile) defines various protection and recovery mechanisms as standards, it does not address methods for calculating and selecting protection and recovery paths. Therefore, an algorithm is needed to calculate and set up paths to ensure quick protection and recovery across the entire integrated network, minimizing conflicts in protection and recovery at the packet optical integrated network level. In this paper, we proposed an algorithm that calculates and sets a path that enables rapid protection and recovery in an MPLS-TP network composed of a multi-ring-mesh topology. To this end, this study proposes the concept of a transparent node (T-node) for calculating link-disjoint SPF (shortest path first) in a multi-ring network with dual or more rings. A T-node is a node in a ring with more than a dual ring and indicates that the node has been used once in route calculation. Therefore, during path calculation, a T-node can be used as a source node and an intermediate node but not as a destination node.