How does it work?

The Community Access Network (CAN) is an interconnected mesh of different networks — decentralised and independent, not unlike the internet, but not directly connected to the internet.

Nodes

To understand how it all “plugs” together, we need to start with our network nodes. A network node is any location that participates in the CAN. These nodes all link together (some directly, but most via other nodes) to form the CAN itself. Some nodes are simply clients who are connecting to the CAN (we call these nodes “Stations”), some nodes offer connections to stations (we call them “Access Points”) and some nodes are designed simply to join two parts of the network together (called “Transit Nodes”).

Here is an example of a station (Bob) connecting to an access point (Mary), who then connects via a transit node (Steve), to another access point (John) who then accepts a network connection from another station (Josh).

example_map

All of these nodes work together to allow you to communicate from one end of the CAN to the other.

Wi-Fi

Now, we could run cables between all these nodes to connect them up, but that would be prohibitively expensive — and to be honest, a lot less fun. So, how do we “plug” them together then? The answer is something you’re probably already familiar with — we use Wi-Fi. The Wi-Fi we use is a a little more specialised than the home Wi-Fi you’re probably used to, in that it uses larger and more complicated antennas, and much more powerful transmitters. This specialised gear allows is to transmit Wi-Fi beyond 30KMs away (and our current longest link is over 50KMs)!

In order to achieve these distances, we require that the nodes can physically see each other (known as having “Line of Sight”). For this reason a lot of our Access Point/Transit nodes are often on high hills, with wide views of their surroundings. Here’s an example of one our sites in Byford, which has a gorgeous view:

byford-view

To connect to an Access Point, you simply bolt a mount to your roof, bolt a radio to the mount, and align it to an Access Point. Depending on your view from your roof, a small pole or mast may be required.

mast-install

Routers

Each access point and transit node use routers in order to send traffic between the nodes. Some access points/transit nodes might have multiple connections to multiple nodes, so the routers are responsible for sending the traffic where it needs to go.

In order to maintain chaos with all the connections between the nodes, we use a feature called dynamic routing, specifically BGP (or “Border Gateway Protocol”). BGP allows each node to tell the next node in the chain what nodes it is connected to. This information is passed node to node until the entire network is mapped out. Each node the uses the BGP information to figure out the best way to get to each node on the network. If a connection between two nodes drops or a node goes offline, BGP will then recompute and work around the problem.

Services

Once you’re connected to the CAN, there’s plenty of services you on offer by many of the node maintainers. Some of the services available include:

  • Online Gaming (Trackmania, Call of Duty, Far Cry and others)
  • File Sharing
  • Streaming Audio/Video
  • File Mirrors
  • Airplane Tracking (ADS-B)
  • Chat/IRC
  • Remote Backups
  • VPNs between sites

Once you’re connected to the CAN, we encourage you to share whatever services you might have to offer (and if they’re really good, we’ll even add them here)!

It’s also worth noting that some other services may be offered by individual node maintainers on a case by case basis. Ask around on our Forums or on IRC to see what else is available!

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