# Routing Protocols for Low Power and Lossy Networks in Internet of Things Applications
## 1 Introduction
The routing protocols for low power networks are summarized in several survey works. The works in [26; 27; 28] presented surveys about initial routing protocols for 6 LoWPAN. A study about a secure routing protocol for IoT was presented in [29]. Considering the Smart Grid (SG) as a kind of IoT application inside the smart city domain [30; 31], the authors in [32; 33] showed survey studies about the routing protocols and network challenges for SG. Most recently, [34; 35; 36] have committed to surveying the existent routing solutions, considering improvements purely for RPL. The weaknesses of the current solutions have motivated the emergence of an increasing number of new protocols and adaptations that seek to improve the network performance and avoid faults. Further, with the RPL-based improvements, it is also possible to find routing solutions for IoT networks based on other routing protocols, e.g., the AODV (Ad-hoc On-demand Distance Vector) routing protocol [37]. Thus, this work aims to present an extensive survey about the existent routing solutions  
failures and route recomputing, and mobility support (with speeds up to 35 km/h) are other routing requirements for industrial LLNs. Through RFC 5826 [20], the RoLL working group has defined the routing requirements for Home Automation LNNs (HA-LLN). Home automation scenarios encompass a great set of applications such as energy conservation and consumption optimization, window shade control, and healthcare [38]. Although the HA applications commonly use wired networks and power-line communication, the use of wireless networks can facilitate application expansion and possible upgrades. The routing requirements for HA-LLNs applications may vary according to the use case. For example, based on the above-mentioned informational RFC, a healthcare HA-LLN application requires a constraint-based routing, with mobility support and low convergence time. On the other hand, an alarm system HA-LLN application requires a network able to provide high scalability and convergence time. Further, the reliable support for different traffic patterns represents an indispensable feature for routing protocols in residential applications. Summarizing, a routing protocol able to support all HA-LLN applications must be ready to provide constraint-based routing and support to mobility, scalability, convergence time, manageability, and stability. In [21], the routing requirements for Building Automation LLNs (BA-LLNs) were described. BA applications include the monitoring of several aspects such as fire alarms, elevator systems, control access, and intrusion detection systems [39]. In this context, wireless devices can increase the flexibility and reduce the deployment costs of applications. The network structure for BA applications should support at least two thousand nodes, including sensors, actuators, controllers, and user interface devices. A complete Building Management Systems (BMS) can be composed from different, smaller applications executed in several subnetworks that are connected through a backbone. Both the traffic pattern and the device density, as well as several other network peculiarities can diverge for each subnetwork. Therefore, the routing protocols must provide a self-organizing structure with zero-configuration to make the installation and replacement of devices accessible. Further, it must also provide scalability and support resource-constrained devices, mobility, addressing, manageability, dynamic route selection, and security. During the definition of the requirements for the different LLN types, IETF studied its existent standard routing protocols. The objective was to identify whether they could attend to the routing requirements of low-power networks [22]. This study has considered the routing protocols for wired and wireless networks. Among these are OSPF (Open Shortest Path First) Version 2 [40], RIP (Routing Information Protocol) Version 2 [41], AODV [37], DYMO (Dynamic Mobile ad hoc network On-demand routing) [42], and DSR (Dynamic Source Routing) [43].