# Building a Community Mesh-Network ISP

## Why We Built It

Our neighborhood started the mesh ISP because the commercial options were either expensive, unreliable, or simply unavailable on the edges of town. The first version was modest: three roof-mounted radios, one borrowed fiber uplink, and a handful of volunteers who were comfortable climbing ladders and reading signal-strength graphs. Within six months, the network had grown into a real access provider with documented installs, monitoring, support rotations, and a small monthly contribution model.

## Network Design

The backbone is a mix of 5 GHz and 60 GHz point-to-point links, with lower-cost 5 GHz sector antennas used for subscriber access. Each rooftop node runs OpenWrt and participates in the routing fabric using Babel, which handles changing link quality better than static routes. We keep customer networks routed rather than bridged, which makes troubleshooting easier and prevents one bad home router from flooding the mesh.

## A Minimal Node Config

```conf
interface mesh0
  type wireless
  hello-interval 4
  rxcost 96

redistribute ip 10.42.0.0/16 allow
redistribute local deny
```

## Operations

The hard part is not the radios; it is operating the network like infrastructure people depend on. Every node exports metrics to Prometheus, and alerts are based on packet loss, link margin, and route churn rather than simple host availability. We also keep spare radios, PoE injectors, and pre-crimped cable in a shared cabinet so outages can be fixed without waiting for shipping.

## Lessons Learned

Community ownership changes the engineering tradeoffs. We choose equipment that residents can replace, configs that volunteers can understand, and topology changes that reduce single points of failure even when they are not the cheapest option. The result is not a carrier-grade network, but it is local, repairable, and fast enough that people trust it for work, school, and daily life.