Low power and Lossy networks (LLNs) are made up of many embedded devices with limited power, memory, and processing resources. They are interconnected by a variety of links, such as IEEE 802.15.4, Bluetooth, Low Power WiFi, wired or other low power PLC (Powerline Communication) links. LLNs are transitioning to an end-to-end IP-based solution to avoid the problem of non-interoperable networks interconnected by protocol translation gateways and proxies.
Generally speaking, LLNs have at least five distinguishing characteristics: - LLNs operate with a hard, very small bound on state. - In most cases, LLN optimize for saving energy. - Typical traffic patterns are not simply unicast flows (e.g. in some cases most if not all traffic can be point to multipoint). - In most cases, LLNs will be employed over link layers with restricted frame-sizes, thus a routing protocol for LLNs should be specifically adapted for such link layers. - LLN routing protocols have to be very careful when trading off efficiency for generality; many LLN nodes do not have resources to waste.
These specific properties cause LLNs to have specific routing requirements.
Existing routing protocols such as OSPF, IS-IS, AODV, and OLSR have been evaluated by the working group and have in their current form been found to not satisfy all of these specific routing requirements.
The Working Group is focused on routing issues for LLN.
There is a wide scope of application areas for LLNs, including industrial monitoring, building automation (HVAC, lighting, access control, fire), connected homes, healthcare, environmental monitoring, urban sensor networks (e.g. Smart Grid), asset tracking. The Working Group focuses on routing solutions for a subset of these: industrial, connected home, building and urban sensor networks for which routing requirements have been specified. These application-specific routing requirement documents will be used for protocol design.
The Working Group focuses only on IPv6 routing architectural framework for these application scenarios. The Framework will take into consideration various aspects including high reliability in the presence of time varying loss characteristics and connectivity while permitting low-power operation with very modest memory and CPU pressure in networks potentially comprising a very large number (several thousands) of nodes.
The Working Group will pay particular attention to routing security and manageability (e.g., self routing configuration) issues. It will also need to consider the transport characteristic the routing protocol messages will experience. Mechanisms that protect an LLN from congestion collapse or that establish some degree of fairness between concurrent communication sessions are out of scope of the Working Group. It is expected that upper-layer applications utilizing LLNs define appropriate mechanisms. The solution must include unicast and multicast considerations.
- Specification of routing metrics used in path calculation. This includes static and dynamic link/node attributes required for routing in LLNs.
- Provide an architectural framework for routing and path selection at Layer 3 (Routing for LLN Architecture) that addresses such issues as whether LLN routing require a distributed and/or centralized path computation models, whether additional hierarchy is necessary and how it is applied.
Manageability will be considered with each approach, along with various trade-offs for maintaining low power operation, including the presence of non-trivial loss and networks with a very large number of nodes.
- Produce a routing security framework for routing in LLNs.
- Protocol work: The Working Group will consider specific routing requirements from the four application documents collectively, and specify either a new protocol or extend an existing routing protocol in cooperation with the relevant Working Group. If requirements from the four target application areas cannot be met with a single protocol, the WG may choose to specify or extend more than one protocol (this will require a recharter of the WG).
- Documentation of applicability statement of ROLL routing protocols.
Submit Routing requirements for Industrial applications to the IESG to be considered as an Informational RFC.
Submit Routing requirements for Connected Home networks applications to the IESG to be considered as an Informational RFC.
Submit Routing requirements for Building applications to the IESG to be considered as an Informational RFC.
Submit Routing requirements for Urban networks applications to the IESG to be considered as an Informational RFC.
Submit Security Framework to the IESG to be considered as an Informational RFC
Submit Routing metrics for LLNs document to the IESG to be considered as a Proposed Standard.
Submit first draft of ROLL routing protocol specification as Proposed Standard.
Submit the ROLL routing protocol specification to the IESG as Proposed Standard.
Submit first draft of RPL threat analysis to the IESG to be considered as an Informational RFC
WG to adopt RPL applicability statement Home for Automation applications