Tech, ExplainedNetworking, infrastructure and security
Concept

Mesh network

Devices passing traffic for each other.

HOW IT WORKSA device has a messageto sendIt hands themessage to aneighbouring deviceEach neighbourpasses it on towardsthe destinationIf one device fails,the others findanother pathThe message reachesits destinationThere is no central device whose failure stops the network, and coverage grows as devices are added.HOW IT WORKSA device hasa messageto sendIt hands themessage to aneighbouringdeviceEachneighbourpasses it ontowards thedestinationIf one devicefails, theothers findanother pathThe messagereaches itsdestinationThere is no central device whose failure stops the network, and coverage grows as devices are added.HOW IT WORKSA device has a message to send↓It hands the message toa neighbouring device↓Each neighbour passes iton towards the destination↓If one device fails, the others findanother path↓The message reaches its destinationThere is no central device whose failure stops thenetwork, and coverage grows as devices are added.
Each device passes a message to a neighbour, which passes it on, until it reaches its destination, and other paths are used if one fails.
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A mesh network is a group of devices that pass traffic on for each other, so that a message can reach its destination even when it is out of range of the main device. It is used in army radios, in home Wi-Fi units that cover a large house, and in sensors spread over a farm. The devices are called nodes.

Here is how it works in general. Each node can exchange messages with the nodes near it. When a node has something to send, it gives the message to a neighbour, which gives it to the next, until it reaches the destination. Each node knows which neighbours it can reach. If one node fails or something blocks a path, the others find another path. So the network keeps working without a central device, and it can cover more ground than any single device could.

Each node chooses a route by signal strength or by the fewest hops. Every hop adds delay and uses some of the shared radio capacity, so the speed drops as the number of hops grows. A mesh is not always the best choice. A fixed tower or router is simpler and faster when every device can reach it. A mesh pays off where laying cable is hard, where the devices move, or where the network must survive when parts of it fail.

Take, for example, a home with three Wi-Fi units on different floors. A phone upstairs connects to the nearest unit, which passes its data from unit to unit to the router; see mesh routers and managed home Wi-Fi. Consider soldiers in a hilly area, each with a radio that relays the others' voice, so that the group stays connected without a tower; see mesh radio. Say sensors on a large farm pass their readings from one to the next until they reach a gateway.

Other pages that use the idea are long-range IoT radio and drone swarms. The radios are often defined in software, as in software-defined radio.

How is it different from a normal network with a central tower or router? In a normal network every device sends its data to the central point. In a mesh network devices send data to each other, so there is no single point whose failure stops everything.

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Networking, infrastructure and security
Industrial tech and mobility
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