MeshCore Regions versus Flood Corridors: Stop Flooding Europe to Message Your Neighbor

Summary

Florian Sager proposes geographic flood corridors for MeshCore as an alternative to region-name tags, which can cause excessive flooding when communicating across borders.

How flooding works

When MeshCore has no known route, every repeater that hears a flood packet repeats it once. This is reliable, but consumes shared LoRa airtime, increasing congestion, collisions, and battery use as networks grow.

Why region tags fall short

Regions are flat string labels rather than geographic hierarchies. Operators must coordinate exact names, and senders must guess which tag will work. Border communities may have no mutually configured tag unless they use a very broad region, such as Europe.

Corridor approach

A sender specifies a chain of geographic circles toward the destination. A repeater forwards the flood only if its position falls within the corridor. Adjacent circles form capsule-shaped sections, keeping the geometry simple enough for MeshCore’s microcontrollers.

Compact encoding

Each circle uses four bytes: 14 bits each for latitude and longitude, plus a 4-bit radius code. Three circles take 12 bytes, and the packet format supports up to eight. The maximum radius is capped to limit corridor width.

Compatibility

Corridor information is carried through a transport-code extension. Older repeaters can still relay the packet using existing region matching, though they cannot geographically filter it. This allows gradual deployment without requiring every repeater to be updated.

Generation and replies

A companion app could build corridors from repeater positions learned through adverts, or fall back to a straight corridor when location data is unavailable. It could preview the corridor and let users adjust its width. Replies can follow the same corridor in reverse.

Flood suppression

A destination-zone flag distinguishes the destination circle from the corridor’s transport section, enabling possible redundancy suppression along the route. In the speaker’s simulation, combining corridor routing with suppression reduced flood transmissions by about 30% and collisions by about 60%, with radio coverage unchanged.

Suppression is proposed as opt-in and fail-open by default, with backbone repeaters excluded.

Project status

The wire format, geometry check, corridor generator, reply reversal, and unit tests are implemented on a feature branch and tested in a mesh simulator. Further integration remains. The speaker presents the work for community discussion before submitting another merge request.

Guides or reviews

No step-by-step guide or product review is presented. The video explains the existing flood and region mechanisms, analyzes their limitations, and outlines a proposed protocol design.

Main speaker

• Florian Sager — presents the MeshCore flood-corridor proposal and its implementation status.