Field Area Router Tunnel Overlay for Mesh Network Routing
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Solution Overview
Problem
In large-scale mesh networks, efficiently routing packets from outside the network to devices within the mesh network is challenging due to the complexity of multiple Field Area Routers (FARs) and overlapping Directed Acyclic Graphs (DAGs, which leads to increased communication latency and bandwidth consumption.
Innovation Solution
Each Field Area Router advertises a common subnet prefix and builds a tunnel overlay among peers, allowing packets destined for devices within the mesh network to be forwarded through the tunnel if the originating FAR lacks a host route, thereby minimizing WAN link communication and reducing the number of host routes advertised.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple FARs are used to provide access for a single mesh network, then reliability and aggregate throughput are improved, but routing complexity and communication latency increase
Solution Approach 1:
The patent segments the routing functionality by introducing a tunnel overlay that separates host route advertisement from packet forwarding. Each FAR advertises aggregated subnet prefixes rather than individual host routes, dividing the routing complexity into manageable segments handled by different components (tunnel overlay for forwarding, aggregated routes for advertisement).
Solution Approach 2:
The tunnel overlay acts as an intermediary layer between multiple FARs and the WAN. It mediates packet forwarding between FARs without requiring WAN traversal, while the routing protocol layer handles aggregated prefix advertisements, thus mediating between the conflicting requirements of multiple FARs and simplified routing.
2Measurement precision
If each FAR maintains host routes for all devices in the mesh network, then packet delivery accuracy is improved, but memory usage and route management complexity increase
Solution Approach 1:
The patent merges multiple individual host routes into aggregated subnet prefixes for advertisement over the WAN. Instead of each FAR advertising or storing routes to every individual device, FARs advertise aggregated prefixes representing groups of devices, combining multiple routing entries into fewer aggregated routes that maintain delivery accuracy while reducing memory usage.
Solution Approach 2:
The patent inverts the traditional routing approach by having FARs advertise aggregated prefixes upward to the WAN rather than having each device advertise individual host routes downward. This inversion allows the tunnel overlay to handle specific device routing while the WAN layer maintains only aggregated routes, reversing the direction and granularity of route advertisement.
3Adaptability or versatility
If packets are forwarded through the WAN link between FARs, then network flexibility and redundancy are improved, but communication overhead and latency increase
Solution Approach 1:
The patent establishes tunnel overlays between FARs in advance before packets need to be forwarded. These pre-established tunnels provide direct forwarding paths, eliminating the need for dynamic WAN route setup and reducing latency. The tunnels are configured beforehand based on aggregated route advertisements, enabling fast packet forwarding without real-time WAN involvement.
Data Source
AI summary
In one embodiment, a particular field area router (FAR), in a local computer network (e.g., a mesh network) having a plurality of FARs, advertises a common subnet prefix assigned to the local computer network into a global computer network. Each of the plurality of FARs of the local computer network is configured to accept any traffic destined to the local computer network, and a tunnel overlay is built among the plurality of FARs. Upon receiving a packet at the particular FAR destined to a particular device in the local computer network, and in response to the particular FAR not having a host route to the particular device, it forwards the packet on the tunnel overlay to another of the plurality of FARs of the local computer network.