Mesh Network Capacity and Congestion

LoRa Channel Capacity

LoRa is a low-data-rate technology. Unlike Wi-Fi, the RF channel is shared by all nodes simultaneously using a CSMA-like approach combined with Meshtastic's managed flooding mesh mechanism (every node rebroadcasts packets that still have hop limit remaining; there is no routing table). Understanding channel capacity helps you design a network that doesn't saturate itself.

Airtime Utilisation Metrics

Meshtastic displays Channel Utilization and Air Utilization percentages in the app. These are your primary indicators of network load. Channel Utilization is measured over a rolling 1-minute window, and the app colour-codes it: green below 25%, orange 25 - 50%, and red above 50%.

• Channel Utilization < 25% (green): healthy. Around the 25% mark the firmware begins to self-throttle - it defers its own transmissions to avoid colliding on a busy channel, so packets are delayed (queued), not dropped outright.
• Channel Utilization 25 - 50% (orange): busy/degrading. Expect added latency as nodes back off and defer.
• Channel Utilization > 50% (red): congested. Sustained load at this level risks queue overflow and real packet loss.
• Air Utilization TX: the fraction of time your node spends transmitting. Keep it low (a few percent is a reasonable target); a high value means your node is contributing a lot of airtime - reduce its broadcast intervals. (There is no documented hard "15%" Air Utilization rule.)

Sources of Traffic in a Mesh

• Position and NodeInfo broadcasts: nodes announce themselves periodically. Position and NodeInfo are separate broadcast types sent at different default intervals (NodeInfo is typically far less frequent than position). As a rough example, 50 nodes each sending a position packet on a 15-minute interval is one position packet roughly every 18 seconds (50 ÷ 900 s) on average - before any user traffic, and before the additional NodeInfo, telemetry, and rebroadcast load. (Verify the exact default intervals against your current firmware/preset, as they vary by role and modem preset.)
• User messages: text traffic generated by operators.
• Telemetry: device metrics (battery, voltage) and environmental sensor readings.
• ACKs and routing overhead: mesh protocol housekeeping packets.

Traffic Reduction Strategies for Dense Networks

• Increase position broadcast interval to 30 - 60 minutes on non-mobile nodes.
• Disable telemetry on nodes where it is not needed.
• Use the Medium Slow or Medium Fast preset - the higher data rate means each packet occupies the channel for less time, even if physical range is unchanged.
• Be deliberate about infrastructure roles. Both ROUTER and REPEATER rebroadcast with elevated priority (they will rebroadcast even after hearing another node do so), so neither is "less aggressive" than the other. The practical difference is that a REPEATER is headless - it does not run the client app or participate in the node database - not that it retransmits less. To actually cut redundant airtime, reduce the number of high-priority infrastructure nodes in range of each other and keep ordinary nodes in the default CLIENT role rather than promoting many of them to ROUTER/REPEATER.
• Limit hop count: most community networks set a maximum of 3 - 5 hops (the firmware default is 3, max 7). Longer hop chains amplify traffic because each hop retransmits every packet.

The Hop Storm Problem

If many nodes retransmit the same packet, a single user message can trigger a burst of dozens of transmissions across the mesh. Meshtastic uses duplicate-packet detection to suppress already-seen packets and prevent routing loops, but in dense networks already near maximum airtime utilisation, a sudden burst of messages can temporarily saturate the channel and cause widespread packet loss. Keeping hop counts low and broadcast intervals long is the primary mitigation.

Monitoring Your Network

Use the Channel Utilization and Air Utilization figures in the Meshtastic app to assess local network load before and after adding new nodes. If deploying a new repeater in a dense area, monitor whether its addition increases congestion - a new high-visibility, high-priority infrastructure node can increase channel load for every other node in range.