Asymmetric Routing for Bidirectional Traffic Self-Interference
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Solution Overview
Problem
Low Power and Lossy Networks (LLNs) face challenges with self-interference due to shared-media communication links, particularly in bidirectional traffic flows, which exacerbate half-duplex communication issues and hidden-terminal problems, leading to reduced network capacity and reliability.
Innovation Solution
A network device detects bidirectional traffic flows and determines self-interference conditions, splitting the traffic to use asymmetric routing paths, where packets in one direction are routed along a primary path and those in the opposite direction are routed along a partially or fully diverse alternate path, mitigating self-interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If bidirectional traffic flows use the same path for both directions, then routing simplicity is maintained, but self-interference increases due to half-duplex communication constraints
Solution Approach 1:
The patent applies asymmetry by routing traffic in opposite directions along different paths. Specifically, unicast traffic from endpoint A to B follows one path while return traffic from B to A follows a different path, eliminating self-interference caused by half-duplex constraints on shared media links.
Solution Approach 2:
The patent segments the bidirectional traffic flow by separating it into two independent unicast flows with distinct paths. This segmentation allows each direction to be routed independently, avoiding the self-interference that would occur if both directions shared the same path.
2Object-generated harmful factors
If asymmetric routing paths are used for bidirectional traffic, then self-interference is reduced, but routing complexity increases
Solution Approach 1:
The patent implements a universal routing mechanism where the RPL protocol simultaneously handles both symmetric and asymmetric routing requirements. The objective function can be configured to select different parent nodes for different traffic directions, providing multi-functional routing capability within a single protocol framework.
Solution Approach 2:
The patent introduces intermediary routing components including the RPL protocol and objective function that mediate path selection. These intermediaries automatically determine and enforce asymmetric paths based on network conditions, reducing the complexity burden on individual nodes while maintaining self-interference mitigation.
3Productivity
If asymmetric routing is implemented, then network throughput is improved by eliminating self-interference, but path selection complexity increases
Solution Approach 1:
The patent changes routing parameters by modifying the RPL objective function to consider asymmetric path selection. The objective function adjusts route metrics and parent node selection based on traffic direction, enabling throughput improvement through parameter-based control rather than complex structural changes.
Solution Approach 2:
The patent implements dynamic path selection where routing paths can change based on network conditions, traffic patterns, and objective function configuration. This dynamics allows the network to adaptively optimize throughput by selecting appropriate asymmetric paths without requiring static complex routing tables.
Data Source
AI summary
In one embodiment, a device in a network detects a bidirectional traffic flow along a primary path in the network. The device determines that a self-interference condition exists along the primary path. The device selects an alternate path in the network. The device causes the traffic flow to use the primary path for packets of the traffic flow sent in a first direction and to use the alternate path for packets of the traffic flow send in a second direction that is opposite that of the first direction.