6LoWPAN

6LoWPAN, short for IPv6 over Low-Power Wireless Personal Area Networks, is a set of IETF standards that enable IPv6 communication over IEEE 802.15.4-based networks. It provides mechanisms for header compression, fragmentation, and an adaptation layer to support the constraints of low-power devices, small link MTUs, and intermittent connectivity.

The architecture introduces a 6LoWPAN adaptation layer that maps IPv6 packets to 802.15.4 frames. It enables IPv6 addressing, including link-local and routable addresses, while using compression to minimize the common IPv6 header from 40 bytes to a few bytes. Fragmentation allows transmission of larger IPv6 packets over the typical 127-byte 802.15.4 payload. The adaptation layer also supports multicast and neighbor discovery optimizations to reduce energy use.

Header compression reduces IPv6 headers, often to 2-3 bytes depending on context, and supports address compression via stateless and stateful mechanisms. Fragmentation allows sending IPv6 packets larger than the 802.15.4 MTU, at the cost of additional header overhead. The adaptation layer also supports multicast and neighbor discovery optimizations to reduce energy use.

Standardization activity began in IETF's 6LoWPAN Working Group. Foundational documents include RFC 4944 (IPv6 over IEEE 802.15.4), RFC 6282 (IP header compression for 6LoWPAN), and RFC 6775 (Neighbor Discovery Optimizations for LLNs).

6LoWPAN is widely used in wireless sensor networks and IoT applications, particularly with low-power meshes and smart energy devices. It is implemented in platforms such as Contiki and Contiki-NG, RIOT, and Zephyr, and serves as a basis for interoperable IPv6-based IoT solutions.

Security for 6LoWPAN relies on the link-layer security provided by IEEE 802.15.4. Additional IP-level security, such as DTLS or IPsec, can be used where appropriate, but fragmentation and reassembly must be carefully managed to avoid attacks.