The 5 min introduction to Mesh Networks and AREDN

This is my attempt to explain what a Mesh Network is, what hardware and software are needed to set one up, why and what can you do with one.

mesh network is a local network topology in which the infrastructure nodes (i.e. bridges, switches, and other infrastructure devices) connect directly, dynamically and non-hierarchically to as many other nodes as possible and cooperate with one another to efficiently route data from/to clients.

MESH – Network of
self-organising and
self-configuring nodes

Using AREDN® as the building blocks

The AREDN® acronym stands for “Amateur Radio Emergency Data Network” and it provides a way for Amateur Radio operators to create high-speed ad hoc Data Networks for use in Emergency and service-oriented communications.

AREDN is the software which enables the mesh to be set up and managed. It is based on two key pieces of software. 

OpenWRT – This is the Open Source Linux based operating system for the node router. Think of this like you think of Windows on your PC, its the base operating system that controls the hardware and provides a platform on which to operate the software.

OLSR – Optimized Link State Routing Protocol, this is the clever bit that ensures the nodes automatically find and join other nodes to create a network. When a new node is switched on it shout “Hello, I’m here who can hear me”. All the other nodes then start a conversation with the new node to find out what it is, where it is, how well they can hear it, what services it can provide, etc. It also ensures data takes the most appropriate route between any two points on the network ensuring nodes are still active and able to pass on messages before they are sent.

Hardware and Frequencies

As it turns out almost every house in the UK has a radio transmitter capable of using parts of the spectrum inside the Amateur Bands. Yeap your trusty internet router has the hardware (maybe not the software option) to use the Amateur sections of 2.4Ghz/3Ghz and 5Ghz bands right out of the box.

However, in order to access these we need to use the AREDN software as mentioned above.

So what hardware has the AREDN software been developed for. There are over 50 devices which are compatible as of early 2020, these include routers and wifi links from manufacturers; Ubiquiti, Mikrotik , TP-Link and GL.iNet (See AREDN website for the up to date product compatibility matrix 

Many of these devices can be picked up second hand on ebay. My first Ubquiti 5Ghz nodes cost me £25!

New TP-LINK routers can be picked up new for less than £50. and the GL.iNet devices are even cheaper (although are mainly designed for local mesh connections of under 1km)

 

 

 

GL.iNET GL-AR150 Mini Router can be picked up new for around £25

The great thing with mesh is it relays messages, so if you nearest node is your next-door neighbour, then a cheap desktop router could connect to the mesh network just by talking to next door but you would be able to communicate with someone the other side of the country/country/world! (As long as your neighbour has a long-distance link to the next node!)

Ubiquiti Networks produce a range of medium and long range devices in all three bands (2.4/3/5Ghz)

These can be used to build neighbour wide mesh networks covering meters to a few miles. Antenna have up to 120 degrees coverage and can be powered from simple passive POE injectors over a standard CAT5 cable. 

 

 

Long range dish or beam antenna’s give upto 30-40miles of range, although these reported ranges are from the states where there is a node set up on top of a mountain top on top of a repeater tower! But still give miles rather than meters of range. Their beams are very narrow and these are really designed to be point to point connections on the network.

Minimal 2 node Station

In the same way as a QSO needs two people (otherwise your just blindly calling CQ with no response) a mesh network needs at least 2 nodes, the more the better!

However you can think of a 2 node station as a “wireless cable”. 

 

Imagine you want to connect two computers across a large field so that you can communicate between the two.

You could run a 200 meter CAT5 cable.

Or you could set up a simple AREDN network with 2 nodes. These would provide you with a virtual cable between the two computers. 

Longer distance linking

Of course the more people running nodes then the bigger and better a mesh is going to be. 

There can also be several local mesh nodes all running on a low powered 5Ghz, interconnected with a backhaul node on 3Ghz. 

This certainly provides wide area networking but dose rely on the “backhaul” nodes to be operational. This is the reason the more nodes on the network the more paths available to route data between two points.

 

Software you can run

Everything I have talked about above has nothing to do with what you can run over the network. The network itself has to be thought of like the virtual cable that connects things together, not the software that you can then run over that virtual cable.

So what can you use this for? Well, as this is effectively like WIFI you can run anything you can run on regular IP Data network. 

You can run Webservers, Chat Networks, Webcams, VoIP Telephones, Email. The list goes on and on!

Setting up each of these services does require one additional step(simplifying this a lot)

Here’s an example.

When you are on your computer and open a browser and type in https://example.com you are routed over the internet to a server somewhere on the globe which is ready to respond and send you the website words and pictures. Just like you connected to this website and my server on the internet provides all the content.

However, a mesh network is not (normally) connected to the internet so when you want to view a webpage, someone has to be running a webserver and store the webpages to server over the mesh network. 

Whilst a mesh network allows you to do all the same things as you can on the internet, it is not connected to the public internet, you can think of it as an amateur radio private internet. So someone has to be running the “Server” side of the service such as a webserver.

This is not a big problem as many people on the network will be providing services, I actually run a VoIP phone system on the network and if you join you get a free telephone number (3 digit number) which anyone else on the network can call you directly on.

Many of these things can be run 24/7 using a lowcost Raspberry Pi. However that is outside the scope of the 5 min introduction…

 

Brilliant, now what?

Well hopefully this introduction has sparked an interest in you and you want to find out more and potentially set up a node to join the network?

Don’t be put off by any of the more technical aspects of this, the process of flashing the firmware can be as simple as uploading a file to the device and putting in a few settings.

You do not need to have advanced networking background, as all of this is taken care of you by the software itself.

I am adding new content throughout the start of 2020 to help people who want to join. The network is new and will take some time to spread its coverage. 

But for now, check out the links to the AREDN information and documentation pages where there are many guides and instructions. They can be found here

Thanks for reading and be sure to join the forum if you have any questions you want answering. 

Andrew, M0ONH