Asymmetric Routing for LLN Downstream Path Quality
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Solution Overview
Problem
Low-Power and Lossy Networks (LLNs) face issues with unstable communication links and asymmetrical path qualities, leading to downstream traffic failures and network congestion due to high centrality nodes handling transit traffic, which makes the network fragile and prone to congestion.
Innovation Solution
The solution involves monitoring downstream path quality in LLNs, detecting unacceptable asymmetric paths, and either modifying next-hop selections or migrating nodes to ensure communication paths meet service level agreements, thereby maintaining network stability and reducing congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If downstream paths are selected based on upstream path quality, then routing simplicity is maintained, but downstream communication quality deteriorates due to asymmetrical link characteristics
Solution Approach 1:
The patent applies asymmetry by implementing separate upstream and downstream routing paths. Upstream routing uses RPL protocol to build Directed Acyclic Graphs (DAGs) toward the root node, while downstream routing independently determines paths from root to end devices. This asymmetric routing structure allows each direction to be optimized for its specific quality requirements, resolving the contradiction between routing simplicity and downstream communication quality.
2Adaptability or versatility
If centrally-located nodes with high centrality are used for transit traffic, then network connectivity is improved, but network stability deteriorates due to congestion and processing pressure
Solution Approach 1:
The patent applies local quality by evaluating and optimizing routing paths based on local link characteristics rather than relying on centralized node capacity. The downstream path selection process assesses individual link qualities (delay, reliability, loss rate) and selects paths that meet quality thresholds, distributing traffic away from overloaded high-centrality nodes to nodes with better local link conditions, thus improving network stability while maintaining connectivity.
3Productivity
If upstream routing is optimized independently, then upstream communication efficiency is improved, but downstream path quality deteriorates due to lack of coordination
Solution Approach 1:
The patent implements feedback mechanisms where downstream path quality metrics are monitored and used to adjust routing decisions. The system continuously evaluates downstream link qualities and feeds this information back into the path selection process, allowing dynamic optimization of downstream paths while maintaining upstream routing efficiency. This coordinated approach ensures both directions achieve their quality targets.
Data Source
AI summary
In one embodiment, a plurality of communication paths in a second direction in a communication network is determined, based on reversing communication paths established in a first direction in the communication network. Then, a path quality of the communication paths in the second direction is monitored. Based on the monitored path quality, it is then determined whether the communication paths in the second direction satisfy a communication requirement. Finally, a particular communication path of unacceptable quality in the second direction is detected when the particular communication path in the second direction fails to satisfy the communication requirement.