Source Route Diversification in Low-Power Lossy Networks
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Solution Overview
Problem
Distance vector routing protocols in Low-Power and Lossy Networks (LLNs) are not well-suited for building completely diverse paths, making it difficult and costly to implement multi-path forwarding, which is crucial for reliable data transmission in critical IoT applications due to high packet error rates and limited resources.
Innovation Solution
The solution involves a source device determining a single source route and generating additional packets with an indication to transit devices to forward them to reachable 1-hop neighbors two hops away from the source route, allowing for dynamic activation of multi-path forwarding for load-balancing and redundancy protection without requiring extensive computation or memory resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If distance vector routing protocols are used in LLNs, then routing is simplified and memory constraints are addressed, but the ability to build completely diverse paths is lost
Solution Approach 1:
The patent segments the path diversity function into two parts: the distance vector routing protocol handles basic routing with simplified complexity, while a separate diverse path computation mechanism (using graph algorithms) handles path diversity requirements. This segmentation allows each component to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent introduces an intermediary diverse path computation mechanism that acts as a mediator between the simplified distance vector routing protocol and the requirement for path diversity. This intermediary layer computes diverse paths based on topology information from the routing protocol without requiring the routing protocol itself to be complex.
2Reliability
If multiple paths are discovered and maintained at the source for multi-path forwarding, then packet delivery reliability is improved, but memory and computation resources are consumed
Solution Approach 1:
The patent performs preliminary computation of diverse paths using graph algorithms based on topology information, storing only the essential path information needed for forwarding. This preliminary action allows the system to prepare diverse path options in advance without maintaining full routing state for all possible paths, thus reducing memory consumption while ensuring reliability.
3Length of stationary object
If path diameter increases to reach more distant destinations, then network coverage is expanded, but packet error rate increases exponentially
Solution Approach 1:
The patent changes the parameter of path selection by computing and selecting from multiple diverse paths with different characteristics (length, hop count, link quality). Instead of using a single longest path, the system can select shorter or more reliable diverse paths based on current network conditions, thus expanding effective coverage while maintaining packet delivery reliability.
4Productivity
If multi-path forwarding is implemented with source routing, then load balancing and redundancy are achieved, but the routing protocol must be capable of building multiple routes which complicates the system
Solution Approach 1:
The patent makes the diverse path computation mechanism universal by designing it to work with any distance vector routing protocol. The graph-based computation can process topology information from various routing protocols and generate diverse paths, providing multi-functionality without requiring protocol-specific modifications, thus achieving load balancing without increasing routing protocol complexity.
Data Source
AI summary
In one embodiment, a source device determines a source route from itself to a destination device in a computer network, and forwards a first packet on the source route with the source route included within the first packet. In addition, the source device generates a second packet with the source route included within the second packet, the second packet also including an indication to cause one or more of a plurality of transit devices to forward the second packet to a reachable 1-hop neighbor of a device in the source route two hops away from the respective transit device. The source device may then forward the second packet itself, as do one the one or more transit devices on a diverse path based on the source route, to a particular reachable 1-hop neighbor of a particular device in the source route two hops away from the source (or transit) device.