doesn’t fit into a single layer; it is a protocol stack that occupies the bottom layers of the OSI model (i.e. layers 1 to 4)
it is designed to be “application-layer agnostic,” meaning it doesn’t define what the application does (like controlling a light or a thermostat), but rather how the data gets from point A to point B

How Thread maps to the OSI model

OSI Layer	Thread Stack Components	Function
Layer 4: Transport	UDP	UDP used for lightweight, low-latency communication
Layer 3: Network	IPv6 / 6LoWPAN / RPL	IPv6 provides addressing 6LoWPAN compresses packets RPL manages mesh routing
Layer 2: Data Link	IEEE 802.15.4 MAC	handles data framing, error detection, and reliable delivery over the air
Layer 1: Physical	IEEE 802.15.4 PHY	the raw radio transmission on the 2.4 GHz spectrum

Other