# Building a Community Mesh-Network ISP

In Northfield, unreliable broadband and high installation costs led residents to build a cooperative wireless ISP. The network began with three fiber-backed rooftop sites and expanded through member-hosted relay nodes. Each household purchases a standard outdoor radio, while the cooperative owns the core routers, address space, monitoring systems, and upstream contracts.

## Network Architecture

Most customer nodes connect over 5 GHz point-to-point or point-to-multipoint links, with 60 GHz radios used for short, high-capacity rooftop paths. Relay sites run a layer-3 mesh using Babel, allowing traffic to reroute when a link fails without extending one large broadcast domain across the neighborhood. Gateways announce a default route into the mesh and connect to redundant upstream providers through BGP.

```conf
protocol babel mesh {
    interface "mesh0" {
        type wireless;
        rxcost 256;
    };
    import all;
    export all;
}
```

## Operations and Reliability

Volunteer installers use a shared survey checklist covering line of sight, mounting, grounding, and expected signal levels. Prometheus collects radio and router metrics, while alerts focus on conditions residents can act on: gateway loss, sustained packet loss, low signal-to-noise ratio, and overloaded sectors. Firmware updates are staged on a test ring before reaching relay nodes, reducing the chance that a bad release partitions the network.

## Capacity and Fairness

The cooperative sells service tiers based on realistic busy-hour capacity rather than radio link rates. Each gateway reserves bandwidth for voice, monitoring, and routing traffic, then applies per-subscriber fair queuing to prevent a single large transfer from dominating a sector. Monthly capacity reviews combine interface utilization, latency under load, retransmission rates, and support reports to identify where new relays or backhaul upgrades will have the greatest effect.

## Governance and Sustainability

Members elect a technical committee, approve major capital expenses, and receive plain-language incident reports. Subscription revenue covers upstream transit, insurance, replacement hardware, pole agreements, and a small emergency reserve; installation labor is paid even when performed by members. That structure keeps the network affordable without depending on indefinite volunteer availability, and it makes reliability, privacy, and expansion decisions accountable to the people who use the service.