Zigbee addressing and packet structure

The Zigbee protocol, as shown, resides on top of the 802.15.4 PHY and MAC layers and reuses its packet structures. The network diverges at the network and application layers.

The following figure illustrates breaking down one of the 802.15.4 PHY and MAC packets into the corresponding network layer frame packet (NWK) as well as the application layer frame (APS):

Zigbee uses two unique addresses per node:

• Long address (64 bit): Assigned by the manufacturer of the device and is immutable. Uniquely identifies the Zigbee device from all other Zigbee devices. This is the same as the 802.15.4 64-bit address. The top 24 bits refer to the organizational unique identifier (OUI) and the bottom 40 bits are managed by the OEM. The addresses are managed in blocks and can be purchased through IEEE. 
• Short address (16 bit): This too is the same as the PAN ID of the 802.15.4 specification and is also optional.