Mesh topology is a type of networking where all nodes cooperate to distribute data amongst each other. This topology was originally developed 30+ years ago for military applications, but today, they are typically used for things like home automation, smart HVAC control, and smart buildings. Within this article, we’ll provide a general overview of how mesh topology works, the benefits and considerations associated with mesh networks, industry standards, and alternatives.
Here's an example WiFi product that uses mesh networking.
Many mesh networks allow radios to spontaneously organize themselves by using something called ad hoc on-demand distance vectoring. This is a reactive protocol using some characteristics of proactive routing—meaning the developer creates some of the routes and identifies nodes to play different roles, like an end node or repeater. In simplified terms, an endpoint doesn’t just act as destination and a source of data, but also as a relay point.
Mesh systems usually rely on a routing table, which tells every node (a) how to communicate with the access point, and (b) how a node should direct traffic that is trying to go somewhere. The routing table assumes that there is not direct communication anywhere in the network except by nodes that have a route to the access point. It’s like a big game of telephone—if you don’t know the route, then you send the message to someone that has the route established. Routing tables are comprised of:
(These are fairly technical topics, and we won’t cover them in much detail here.)
Mesh networks operate in two ways: by either routing the data or flooding the data. When you’re routing a message in a mesh network, it propagates along a predefined path, hopping from node to node until it reaches its destination. In order to establish these routes and ensure that the paths are available, the network needs to be continuously connected and configuring itself. In other words, it has to constantly work to find broken paths and create self-healing algorithms to build route tables. Because there’s a lot of layer two (MAC) traffic flowing on the network to establish this route, mesh networks can be less efficient than star networks (which we’ll cover in a moment).
A simpler mesh network takes a flood approach, where the data flows continuously throughout the network. If a module sees data with its address, it simply grabs it. This works because of the time to live, or TTL, value where messages are allowed to propagate through the mesh for only a fixed number of hops before they are removed.
One of the most popular and well-known mesh network is ZigBee. Other well-known mesh topologies include:
An Alternative To Mesh Topology
Mesh networks are not the only way to solve low power network needs for enterprise and industrial smart applications. In fact, a wide majority of low power, wide-area network (LPWAN) technologies use a star-topology network, where the endpoints are connected directly to the access point. Make sure you do your due diligence on all network types before arriving upon which topology will work best for you.