Multicast Distribution Tree Construction via Graph Pruning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current multicast routing technologies face challenges in efficiently generating minimum cost shortest path trees, leading to increased computational complexity and bandwidth inefficiencies due to packet duplication and excessive state generation in networks using MPLS, SPB, and SPRING architectures.
Innovation Solution
A method is implemented to simplify the network topology graph by computing shortest paths, determining adjacency metrics, and pruning the graph to resolve multicast distribution trees, resulting in a near-minimum cost tree with reduced computational complexity and avoiding packet duplication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a full mesh of unicast tunnels is constructed via every node computing the shortest path to every other node, then multicast delivery efficiency is improved, but device complexity and computational complexity increase significantly
Solution Approach 1:
The patent segments the full mesh unicast tunnel construction into two parts: (1) compute shortest paths only from the multicast source to all other nodes, and (2) use these paths to construct the multicast distribution tree. This segmentation avoids the O(N²) complexity of all-pairs shortest path computation while maintaining efficient multicast delivery.
Solution Approach 2:
The patent extracts only the necessary shortest path information from the complete all-pairs shortest path computation. Specifically, it extracts shortest paths from the source node S to all destination nodes, discarding the redundant path information between other node pairs that is not needed for multicast distribution.
2Loss of time
If source specific tree implementation of multicast groups is implemented, then multicast delivery latency is reduced, but state generation in the network increases significantly
Solution Approach 1:
The patent makes the computed shortest path tree universal for all multicast groups sharing the same source. The same tree structure serves multiple multicast groups simultaneously, eliminating the need to generate separate state for each group while maintaining low latency delivery for all groups.
Solution Approach 2:
The patent merges the multicast distribution trees of multiple groups sharing the same source into a single shared tree. By combining the traffic flows and using a common distribution structure, the network reduces the total state that must be maintained while still providing efficient delivery to all groups.
3Device complexity
If IEEE 802.1aq algorithms are applied to compute common template solution for all MDTs, then control messaging convergence is simplified, but packet duplication occurs in ECMP networks
Solution Approach 1:
The patent applies local quality by making the multicast distribution tree specific to each source-destination pair rather than using a universal template for all destinations. The tree structure is optimized locally for each destination node, ensuring that packets take the most efficient path without duplication even in ECMP networks.
Solution Approach 2:
The patent introduces dynamics by adapting the multicast distribution tree structure based on the specific characteristics of each destination node and the current network state. Rather than using a static template, the tree is dynamically constructed to avoid packet duplication while maintaining convergence efficiency.
Data Source
AI summary
A method is provided that is implemented by a network device to simplify a topology graph of a network to generate a multicast distribution tree, the method to reduce the complexity of the topology graph while enabling a creation of the multicast distribution tree such that the computational complexity of generating the multicast distribution tree is reduced, the method including computing a shortest path to all nodes of the topology graph rooted at a source node S, determining a metric for each adjacency on each shortest path of the topology graph for the multicast group G, construct an (S, G) graph with only source node S, leaves and candidate replication points, and prune the (S, G) graph using a set of pruning processes to fully resolve the multicast distribution tree, where full resolution can be determined, and the first set of pruning processes if successful are known to produce a minimum cost tree.