DAG Network Unreachable Node Detection and Tunneling
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Solution Overview
Problem
Low Power and Lossy Networks (LLNs) face challenges in detecting and re-routing messages to unreachable nodes due to variable communication conditions, leading to network instability and unreachable nodes, which existing routing protocols like RPL struggle to address effectively.
Innovation Solution
A mechanism where a node in a directed acyclic graph (DAG) topology identifies unreachable nodes, determines their scope, and tunnels a redirected message to a reachable adjacent node, which then distributes it to the unreachable nodes using time-to-live parameters, allowing the unreachable nodes to initiate new DAO messages and update the DAG routing topology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional routing protocols like RPL are used in LLNs, then the network can operate with low power and lossy links, but unreachable nodes cannot be effectively detected and re-routed, leading to network instability
Solution Approach 1:
The patent applies preliminary action by proactively detecting unreachable nodes before they cause complete communication failure. The root node identifies unreachable nodes and determines their scope in advance, then pre-establishes alternative routing paths through tunneling redirected messages to adjacent reachable nodes, which then distribute messages to previously unreachable nodes via new DAO messages.
Solution Approach 2:
The patent uses an intermediary approach by introducing a tunneling mechanism with redirected messages as intermediaries between the root node and unreachable nodes. The reachable adjacent nodes act as mediators that receive redirected messages and distribute them to unreachable nodes, enabling indirect communication paths when direct routes are unavailable.
2Reliability
If the network attempts to maintain connectivity to all nodes, then network availability improves, but control plane overhead increases due to continuous discovery and re-routing operations
Solution Approach 1:
The patent applies local quality by determining the scope of unreachable nodes rather than treating the entire network uniformly. The root node identifies specific unreachable nodes and their local scope, then applies tunneling and message distribution only to affected regions, reducing unnecessary control plane operations in stable parts of the network.
Solution Approach 2:
The patent uses partial action by implementing selective message distribution rather than universal broadcasting. The reachable adjacent nodes distribute redirected messages only to determined unreachable nodes within the scope, rather than flooding the entire network, thereby reducing control plane overhead while maintaining necessary connectivity.
Data Source
AI summary
In one embodiment, a node (e.g., a root-node) of a currently known directed acyclic graph (DAG) topology of a computer network can identify a sub-DAG of one or more nodes that are unreachable. The node can further determine a scope of the unreachable nodes of the sub-DAG and tunnel a redirected message to a reachable node of the DAG topology that is adjacent to at least one of the unreachable nodes of the sub-DAG. The redirected message may cause the reachable node to distribute the redirected message to one or more of the unreachable nodes of the sub-DAG based on the scope.