Connecting Cities: Linking Mesh Networks via MQTT

While radio nodes are designed to thrive off-grid, you can combine distant radio clusters across the world into a massive hybrid grid using the internet and MQTT brokers.

🌐 1. What is MQTT and Why Use It?

MQTT (Message Queuing Telemetry Transport) is a lightweight, publish-subscribe network protocol perfect for narrow-bandwidth communication. In the Meshtastic ecosystem, MQTT acts as a global software highway. If your city network is separated from another town by hundreds of miles of mountains or empty fields, an internet-connected node can act as an orbital bridge, routing radio waves down into a server pipe and projecting them back out of radio antennas in another corner of the globe.

🛠 2. How the Hybrid Mesh-Internet Topology Works

To establish a global link, your off-grid node does not need a direct connection to the web. Instead, the network structural framework uses an endpoint bridge setup:

📡 Local Radio Cluster (Off-Grid)

Standard pocket nodes carry texts over regular airwaves across city blocks. No internet, completely sovereign and powered by batteries.

🔌 The Gateway Node (Internet Connected)

One static home or rooftop node connects to local Wi-Fi. It intercepts incoming radio packets and securely forwards them up to a central web server directory.

⚙️ 3. Quick Step-by-Step MQTT Configuration

To link your home base node to the global map network, configure the integrated settings inside your Mobile App interface:

  1. Open your app settings and navigate to the Module Settings ➡️ MQTT tab window.
  2. Toggle the Enable MQTT switch to active.
  3. Enter the server host address (the official public server defaults to `mqtt.meshtastic.org`).
  4. Define your channels: check JSON Output if you intend to feed the incoming data arrays into custom web map scripts or dashboard computers.

📊 MQTT Integration Modes Summary

Depending on how you want your off-grid radio grid to interact with public internet nodes, choose the appropriate data sync profile:

MQTT Sync Profile Data Flow Direction Radio Channel Load Best Deployment Use Case
Uplink Only (TX) Radio ➡️ Internet Zero Load Remote weather monitoring, sending telemetry without clutter
Downlink Only (RX) Internet ➡️ Radio Extremely High Injecting remote central emergency warnings into a city grid
Bidirectional (TX/RX) Radio 🔄 Internet High (Requires Filtering) Bridging two distinct private family loops across continents
⚡ Blackout Behavior: What Happens When the Internet Dies?

The main hazard of an MQTT hybrid layout is its reliance on a commercial web connection. During severe regional blackouts, how does the system adapt?

  • Graceful Local Degradation: If the local internet router drops or fiber backhauls cut out due to a lack of power, the node automatically ignores the server parameters. The station immediately shifts back into a **100% autonomous local radio router**, keeping your immediate neighborhood connected without freezing or dropping traffic.
  • Store and Forward Server Queues: Advanced online MQTT cluster configurations track your home node ID. If your station disappears from the server link, messages waiting in line are cached safely and flushed down the link the moment your solar gateway module regains web connectivity.

🌐 Bridging Global MQTT Data directly to Mobile SMS Gateways

Connecting distinct cities over an internet server pipe is a massive upgrade to your network's capability. But what if the target user doesn't even have a radio unit? By combining MQTT scripts with automated terminal servers, you can configure an ultimate hybrid link. An off-grid user in City A transmits a radio wave, it travels over the web via MQTT to City B, hits an automated cellular gateway, and automatically translates into a standard public SMS message delivered straight to any common mobile phone worldwide.