Selective Forwarding in Low Power Lossy Networks
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Solution Overview
Problem
Low Power and Lossy Networks (LLNs) face challenges such as high energy consumption due to multiple transmission attempts, resource constraints like memory and processing capability, and the need to maintain routing states, which can lead to network disconnection and inefficient energy use.
Innovation Solution
A node in a shared-media communication network enters a selective forwarding mode when resources are low, ceasing to forward non-critical messages and notifying neighboring nodes, allowing it to conserve resources for critical traffic, and a management node determines an alternate path to ensure service level agreements are met for all traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a node forwards all traffic (critical and non-critical messages) in a Low Power and Lossy Network, then network coverage and service level agreement compliance are maintained, but energy consumption increases and resource depletion accelerates
Solution Approach 1:
The patent segments traffic into critical and non-critical categories, allowing nodes to selectively forward only critical messages when resources are low. This segmentation enables differential treatment of traffic types based on network conditions and resource availability, resolving the contradiction between maintaining service level agreements and conserving energy.
Solution Approach 2:
The patent implements dynamic routing capability where nodes can switch between full forwarding mode and selective forwarding mode based on their resource levels. This dynamic adaptation allows the network to maintain reliability when nodes have sufficient resources while conserving energy when resources are depleted, directly addressing the technical contradiction.
2Use of energy by moving object
If a node operates with limited resources in a Low Power andLossy Network, then energy consumption is reduced, but network connectivity may be lost and routing states cannot be maintained
Solution Approach 1:
The patent introduces dynamic routing capability as an intermediary mechanism that allows nodes with limited resources to maintain network connectivity indirectly. When a node cannot maintain routing states, the dynamic routing capability enables alternative paths to be established through other nodes, preserving network connectivity while allowing the resource-constrained node to operate in a lower-power state.
3Reliability
If multiple transmission attempts are made to send packets across a Low Power andLossy Network, then delivery reliability is improved, but energy consumption increases significantly
Solution Approach 1:
The patent applies partial action by implementing selective forwarding where nodes forward only critical messages when resources are low, rather than attempting all transmissions. This partial forwarding approach maintains essential network functionality and critical communication while reducing the number of transmission attempts for non-critical traffic, thereby lowering energy consumption while preserving necessary reliability.
4Productivity
If nodes maintain routing states and perform routing table lookups in a Low Power andLossy Network, then routing efficiency is improved, but memory and processing resources are consumed
Solution Approach 1:
The patent implements dynamic routing capability that allows nodes to adapt their routing behavior based on resource availability. When resources are sufficient, nodes maintain full routing states and perform efficient routing table lookups. When resources are depleted, nodes transition to a mode with reduced routing functionality, dynamically adjusting the balance between routing efficiency and resource consumption.
Data Source
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AI summary
In one embodiment, a particular node in a shared-media communication network determines a resource level and in response to determining a trigger condition (e.g., that the resource level is below a threshold), the particular node enters a selective forwarding mode. In the selective forwarding mode, the particular node does not forward non-critical messages. The particular node also notifies one or more neighboring nodes in the shared-media communication network of the entered selective forwarding mode. In another embodiment, a node may receive from a neighboring node, an indication of having entered a selective forwarding mode, and in response the node may forward only critical messages to the neighboring node.