How Mesh Routing Works

When two nodes are too far apart to communicate directly, intermediate nodes relay the message. Meshtastic and MeshCore solve this differently.

Flooding (Meshtastic)

When a node receives a packet,new packet it rebroadcasts toit allonce neighbors.- Eachunless it first hears another node rebroadcastsrelay oncethe same packet, in which case it stays quiet (duplicatemanaged flooding). Duplicate detection prevents loops).loops. The message floods outward until it reaches its destination or exhausts its hop count (typicallydefault 33, -configurable 5up hops)to 7).

• Simple and robust: No routing tables. New nodes work immediately. Self-healing if relay fails. (Since Meshtastic 2.6, direct messages additionally use a learned next-hop relay, with automatic fallback to flooding, so some routing state does exist for DMs.)
• Limitation: OneIn a dense mesh, a single message can trigger 30dozens -of 50rebroadcasts. transmissionsThis acrossis a dense network. Whywhy faster presets (Mediumsuch Slow)as MediumFast are preferred in networksdense with many nodes.networks.

Path-based routing (MeshCore)

MeshCore discovers explicit routes before sending data:

1. Node AA's broadcastsfirst amessage pathis discovery packet;flood-routed; each relayrepeater that relays it appends its identityID to the packet's path
2. Destination node D sends back a pathdelivery acknowledgmentreport alonglisting the reverserepeaters the message traversed; this report is flood-routed back to A and becomes the basis for the future direct path
3. Node A caches the route A → B → C → D and uses it for all subsequent messages to D

• More efficient at scale: Messages travel only the established path - much less airtime than flooding in large networks
• Limitation: RouteThe discoveryfirst adds latencymessage to firsta contact.new contact is flooded (using more airtime); the efficient direct path only kicks in from the second message onward. Topology changes require re-discovery.

Which is better?

Both work well in practice. Flooding is simpler and more resilient for small-to-medium networks (under ~100 nodes).networks. Path-based routing scales better for large infrastructure deployments. In practice, your choice is determined by which protocol your local community uses.

The mesh advantage

EveryIn additionalMeshtastic, every node is a potential relay.relay; in MeshCore, only nodes flashed as repeaters relay - client nodes deliberately do not. A hilltop repeater that can hear both a valley and a distant mountaintop effectively bridges those two coverage zones for all messages. A few well-placed infrastructure nodes have outsized impact on total network reach.