The 6lo (IPv6 over Networks of Resource-constrained Nodes) Working Group (WG) was formed in August 2013, cochaired by Ulrich Herberg and Samita Chakrabarti, under the leadership of Brian Haberman as Internet area director and Ralph Droms as technical advisor.
The WG is a successor of the 6LoWPAN WG, with a primary difference that 6lo defines specifications for running IPv6 over multiple constrained L2 technologies that use a base 6LoWPAN stack (RFC 4944, RFC 6282, RFC 6775) for the IPv6 low-power adaptation, stateless header compression and Neighbor Discovery Optimization for reduced multicast and reliable communication (Figure 1.)
6lo defines specifications for IPv6 over constrained node networks comprising:
- Limited power, memory, and processing resources
- Hard upper bounds on state, code space, and processing cycles
- Optimization of energy and network bandwidth usage
- Lack of some Layer 2 services, such as complete device connectivity and broadcast/multicast
Since its formation, the 6lo WG has produced IPv6-over-BLUETOOTH Low Energy (RFC 7668) and IPv6-over-Zwave (RFC 7428), and has been working on documents, including IPv6-over-DECT Ultra Low Energy, IPv6-over-BACNET Master-Slave/Token-Passing networks, IPv6-over-Near Field Communication, extensions for LOWPAN dispatch functions, and a new ethertype request document for assigning a new ethertype for LOWPAN encapsulated IPv6 datagrams. Find the latest status of documents at https://datatracker.ietf.org/wg/6lo/documents/.
Recently, the Wi-Sun Alliance (https://www.wi-sun.org/) showed interest in deploying the 6lo stack with IEEE 802.15.9 Multiplexed Data Services. It intends to use the 15.9 Multiplexed Data Information Element to dispatch LoWPAN encapsulation frames to upper stack layers.
The 6lo stack is also under consideration for the Wifi Alliance’s HaLoW standard (low-power operation in 900 MHz band), on IEEE 802.11ah and Low-Power Wide Area Networks. The Bluetooth SIG also supports the 6lo-stack by defining a special IP profile (IPSP) in the Bluetooth specifications. RFC 7668 states “Bluetooth SIG has also published the Internet Protocol Support Profile (IPSP), which includes the Internet Protocol Support Service (IPSS). The IPSP enables discovery of IP-enabled devices and establishment of a link-layer connection for transporting IPv6 packets. IPv6 over Bluetooth LE is dependent on both Bluetooth 4.1 and IPSP 1.0 or more recent versions of either specification to provide necessary capabilities.”
The 6LoWPAN or the 6lo stack could be a unifying standard for running IP protocols over the multitude of Internet-of-Things (IoT) L2 technologies that today require many application gateways to convert packets to IP networks connecting to data centers or other IoT networks.
The 6lo stack supports UDP with compression and RFC 7400 defines generic header-compression mechanisms for further applicability in the constrained node networks. In addition to the RFC 4944 adaptation layer and RFC 6282 IPv6 header-compression mechanism, RFC 6775 allows device registration and minimal or no multicast in energy-sensitive networks. The output and concept of the 6lo WG, in some cases, may be applicable in non-6LoWPAN node networks where energy preservation and stateless header compressions are critical.
The WG welcomes work on IPv6-over-foo, 6LoWPAN stack improvements, use-case driven header-compression mechanisms that can work with RFC 4944, network access security solutions, support for reliable communications over deterministic networks, and any energy-sensitive L2-wireless or wired technologies.
The 6lo WG is run by its cochairs, Gabriel Montenegro and Samita Chakrabarti and the responsible area director is Suresh Krishnan. For more information or to read the WG charter, visit https://datatracker.ietf.org/wg/6lo/charter/.