Steiner Tree Multicast Path Finding Under WSS Branch Limits
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Solution Overview
Problem
Existing technologies face challenges in constructing a Steiner tree that satisfies constraints, particularly due to limitations on the number of branches for nodes in wavelength selective switches (WSS) used in optical multicast networks.
Innovation Solution
A communication path search device and method that manages network device specifications, topology, and link information to construct a Steiner tree by adjusting link costs when branch constraints are exceeded, ensuring compliance with maximum branch limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a Steiner tree is constructed to minimize total path length in an optical multicast network, then the efficiency of wavelength utilization is improved, but the constraint on the maximum number of branches at each node (WSS port limit) is violated
Solution Approach 1:
The patent modifies the Steiner tree construction by changing the parameter of branch degree at each node. Specifically, it enforces a constraint that the number of branches at any node cannot exceed the maximum port number of a WSS, transforming the unconstrained Steiner tree problem into a constrained optimization problem that satisfies both efficiency and reliability requirements
Solution Approach 2:
The patent segments the multicast tree construction process into multiple steps: first constructing a preliminary Steiner tree, then identifying and resolving constraint violations by adjusting the tree structure. This segmentation allows the system to first optimize for efficiency and then correct for constraint satisfaction separately
2Reliability
If the number of branches at each node is limited to satisfy WSS port constraints, then the feasibility of the multicast path is improved, but the total path length and complexity of tree construction increase
Solution Approach 1:
The patent performs preliminary actions by first constructing a Steiner tree without considering branch constraints, then identifies nodes that violate the maximum branch constraint. This preliminary construction followed by targeted correction reduces the overall complexity compared to constructing a constrained tree from scratch
Solution Approach 2:
The patent introduces an intermediary step of calculating and comparing the number of branches at each node against the WSS port limit. This intermediary check acts as a mediator between the unconstrained Steiner tree construction and the final constrained solution, allowing systematic resolution of conflicts
Data Source
AI summary
An aspect of the present invention is a communication path search device that constructs a multicast path of a plurality of nodes connected to a network, the communication path search device including a network device information management unit configured to manage a device specification including constraint information on the number of branches of each of the nodes on the network, a network topology management unit configured to manage link information between the nodes on the network, and a multicast tree calculation unit configured to construct a Steiner tree of a path connecting a start node and an end node based on a new request, an existing request, the constraint information on the number of branches of each of the nodes, constraint information on a maximum number of branches of each of the nodes, and the link information, the new request and the existing request each including start node and end node information.