Multicast Tree Tracing via Network Controller Probes

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Solution Overview

Problem

Existing technologies lack an efficient and deterministic method to trace multicast routing trees hop-by-hop in a downstream direction, making it difficult to identify failures and monitor large-scale multicast networks.

Innovation Solution

A method involving a network controller that collects operational configuration information from routers, constructs a topological view of the multicast tree, and uses multicast probes (both replicate and forward, and loopback) to trace the tree, detect failures, and validate the multicast tree.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Difficulty of detecting and measuring

If existing trace tools are used to trace multicast tree, then one leg of the multicast tree can be traced, but there is no efficient and deterministic way to determine the branches of the multicast tree on which the receivers lie, making full downstream tracing difficult

Engineering Contradiction:

Improvedifficulty of tracing multicast treeVSAvoidprecision of tracing accuracy

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The patent segments the multicast tree tracing into multiple independent components: (1) building the multicast forwarding graph from router operational configuration information, (2) injecting probes at the root router, (3) propagating probes through the tree using replicate-and-forward logic, and (4) collecting probe responses to reconstruct the complete downstream path. This segmentation enables systematic traversal of all branches without requiring a single complex tracing mechanism.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces probe packets as intermediaries to facilitate tracing. These probes are injected at the root router and propagated through the multicast tree to reach leaf routers. The probes act as mediators that carry tracing information through the network, allowing the root router to indirectly query the state of all downstream nodes and branches without direct complex interactions with each individual receiver.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If multicast networks operate on large scale with hundreds of thousands or millions of multicast flows, then network capacity is improved, but monitoring and debugging becomes increasingly difficult

Engineering Contradiction:

Improvenetwork capacityVSAvoidcomplexity of monitoring and debugging

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent enables the multicast network to trace itself by utilizing existing router operational configuration information and forwarding logic. The routers themselves provide the necessary topological data and probe forwarding behavior, eliminating the need for external complex monitoring infrastructure. The network's own operational characteristics are leveraged to perform self-diagnosis and self-monitoring.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent makes the multicast forwarding graph and probe mechanism serve multiple functions: (1) validating the multicast tree topology, (2) tracing complete downstream paths to all receivers, (3) identifying failure nodes and affected branches, and (4) providing monitoring capabilities. This multi-functionality consolidates what would otherwise require multiple separate systems into a single integrated tracing mechanism.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If hop-by-hop tracing is performed in downstream direction, then complete path identification is achieved, but no efficient and deterministic method currently exists to determine all branches

Engineering Contradiction:

Improveprecision of path identificationVSAvoidefficiency of tracing process

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent performs preliminary actions by first collecting operational configuration information from all routers in the multicast network to build the multicast forwarding graph before actual tracing begins. This pre-processing step creates a complete topological representation of the network, allowing the subsequent probe injection and propagation to efficiently traverse all branches without requiring real-time discovery or complex on-demand determination of network structure.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12301404B2In-situ operations, administration, and maintenance extension to trace multicast tree and identify failure node

Publication Date: 2025.05.13 CISCO TECHNOLOGY INC

AI summary

A method is performed by a network controller that is configured to control routers configured to forward a multicast flow downstream from a first hop router that is a root of a multicast tree formed by the routers to last hop routers that terminate branches of the multicast tree, respectively. The method includes collecting operational configuration information from the routers and constructing a topological view of the multicast tree based on the operational configuration information; causing the routers to forward multicast probes downstream from the first hop router along all of the branches toward the last hop routers to trace the multicast tree; receiving, from particular ones of the last hop routers that received the multicast probes, indications that the multicast probes were received; and detecting failures in the multicast tree based on the indications and the topological view.