# Building a Community Mesh-Network ISP

In Northbridge, unreliable broadband led residents to build a nonprofit wireless ISP using rooftops, church towers, and volunteer-hosted relay sites. The network now serves roughly 280 homes across 14 square kilometers. Each subscriber installs a directional 5 GHz radio aimed at a nearby distribution node, while a smaller number of 60 GHz links provide high-capacity backhaul between neighborhoods.

## Network Architecture

The network is a routed partial mesh rather than a single Layer 2 broadcast domain. Every node runs OpenWrt and exchanges routes with its neighbors using Babel, which reacts quickly when rain, construction, or equipment failure disrupts a path. Subscriber prefixes are isolated with VLANs, and two fiber connections at opposite ends of town provide redundant internet transit.

```conf
config babeld 'mesh'
    option enabled '1'
    list interface 'mesh_5ghz'
    list interface 'backhaul_60ghz'
    option local_port '33123'
```

## Operations and Capacity

A Prometheus server collects signal strength, airtime utilization, packet loss, and power status from each relay. Volunteers receive alerts when a link remains below −72 dBm or exceeds 75 percent channel utilization for more than ten minutes. During evening peaks, traffic shaping protects DNS, voice, and interactive sessions without prioritizing particular commercial services.

## Reliability in the Field

Power and mounting hardware cause more outages than routing software. Critical relay sites use grounded masts, weatherproof enclosures, and small lithium battery systems sized for four hours of operation. Spare radios are preconfigured and labeled, allowing a trained volunteer to replace failed equipment without needing access to routing credentials.

## Governance and Growth

Members pay a modest installation fee and a monthly rate that covers transit, replacement hardware, insurance, and tower leases. Technical decisions are documented publicly, while privacy-sensitive logs are retained only as long as required for troubleshooting. Expansion is approved block by block after a survey confirms clear paths, available spectrum, and enough capacity to avoid degrading service for existing members.