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Protocols

MQTT-SN

A variant of MQTT for sensor networks that runs over UDP or non-IP links, replaces topic strings with short IDs and lets devices sleep between messages.

MQTT for Sensor Networks keeps the publish-subscribe model of MQTT but strips out the parts that depend on a TCP connection. Messages can travel over UDP, Zigbee or any datagram link, topic names are registered once and then referenced by a two-byte ID, and a sleeping client can ask a gateway to buffer messages until it wakes. A transparent or aggregating gateway converts MQTT-SN traffic into regular MQTT for the broker.

The protocol exists because constrained radios cannot afford TCP handshakes or full topic strings in every packet. It is used in some LPWAN and 802.15.4 deployments and in a few platform SDKs, but it never reached the ubiquity of MQTT itself, so tooling and broker support are thinner. Teams on constrained networks often weigh it against CoAP, which has broader standards backing. MQTT explained covers the parent protocol.

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