DevAddr

DevAddr is a 32-bit device address used in the LoRaWAN protocol to identify a device on the network. It is included in the MAC layer header of uplink frames and is used by the network server to route messages to the correct device. DevAddr is distinct from the device’s identifiers used during joining, such as the EUI, and it is managed by the network operator.

Assignment and activation

DevAddr is assigned by the network server. In OTAA (Over-The-Air Activation), a DevAddr is provided to the device as part of the Join Accept message after a successful join, and it may be re-assigned if the device later rejoins. In ABP (Activation By Personalization), the DevAddr is pre-provisioned by the network operator and remains fixed for the device within that network. The DevAddr is used together with the network session key (NwkSKey) and the application session key (AppSKey) to secure communications.

Structure and routing

The DevAddr is a 32-bit value designed to support efficient routing within a LoRaWAN network. Part of the address encodes a network identifier, enabling network servers and regional components to determine the appropriate routing context. While it is intended to be unique within a given LoRaWAN network, it is not guaranteed to be globally unique across all networks. The exact bit allocation can vary by region and net ID scheme, but the general purpose is to identify the device for MAC-layer demultiplexing.

Usage in frames and security

The DevAddr appears in the FHDR (Frame Header) of both uplink and downlink frames. It is transmitted in the clear as part of the header, while payload confidentiality is provided by the session keys. The DevAddr itself does not provide encryption or integrity protections; those protections come from the network and application keys.

See also

LoRaWAN, OTAA, ABP, NwkSKey, AppSKey, NetID.