# Building a Community Mesh-Network ISP

## From Rooftops to a Regional Network

Our community ISP began with six rooftop radios and a single fiber uplink in a neighborhood where conventional broadband was expensive and unreliable. Each member site hosts a small outdoor router that connects to at least two nearby nodes over 5 GHz point-to-point links. Taller buildings act as relays, while schools and local businesses provide power, mounting space, and backup connectivity.

## Routing and Failure Recovery

The mesh uses Babel for dynamic Layer 3 routing rather than extending one large Ethernet segment across wireless links. Every router advertises its local subscriber subnet and measures link quality continuously. When rain, interference, or a power failure degrades a path, traffic typically moves to another route within seconds without requiring a central controller.

```conf
protocol babel mesh {
    interface "mesh*" {
        type wireless;
        hello interval 2 s;
        update interval 8 s;
    };
    ipv4 { import all; export where source = RTS_DEVICE; };
}
```

## Internet Transit and Addressing

Two gateway sites connect the mesh to independent upstream providers. Subscriber traffic uses carrier-grade NAT for IPv4, but every household receives a delegated IPv6 prefix so devices can communicate without additional address translation. Gateway preference is distributed through routing metrics, allowing the secondary uplink to take over automatically when the primary circuit fails.

## Operating the Network

Reliability depends as much on maintenance as topology. Each node reports signal strength, packet loss, temperature, and battery status to a monitoring cluster hosted inside the mesh. Alerts are sent only after several failed checks, which prevents brief wireless fades from waking volunteers. Firmware releases are staged on test nodes before being rolled out neighborhood by neighborhood.

## Governance and Growth

Members pay a monthly fee that covers transit, replacement hardware, insurance, and a small emergency reserve. Technical decisions are documented publicly, and major upgrades require approval from an elected operations committee. This structure keeps the network accountable to its users while giving trained volunteers enough authority to respond quickly when infrastructure fails.