# DYNASTI--Dynamic Multiple RPL Instances for Multiple IoT Applications in Smart City
## 1 Introduction  
The recent emerging advances on the Internet of Things (IoT) [1; 2] can be easily found several smart mobile and fixed devices (e.g., sensors, cameras, 3D glasses, actuators, and several others). When the resources of these smart devices are combined each other, they offer new monitoring and control capabilities which are able to perform intelligent activities [3; 4]. There are a lot of IoT wireless technologies and protocols (e.g., Long Range (LoRa)/LoRaWAN, NarrowBand-IoT (NB-IoT), LTE-M, SigFox, ZigBee, and among others [5; 6; 7]) that can be applied to provide communication for the smart devices. For instance, a very actual and interesting solution is the LoRaWAN Class B that can be applied for the coordination of distributed interface protection systems in smart grids [8]. In this context, several new application scenarios and networks arise, such as autonomous controlling in smart grid applications [9; 10], smart parking management [11], and smart campus which is a small scale sample of smart cities. For instance, Neighborhood Area Network (NAN) in smart grid enables power distribution with the ability of monitoring and controlling electricity delivery in specific areas. Most of these scenarios have multiple applications deployed in the network [9; 12; 13]. These multiple applications have different traffic patterns (e.g., regular, sporadic, different sending intervals between messages, etc. ); the regular applications that communicate constantly throughout the network lifetime and, sporadic applications that demand communication for a short period of time and usually have critical requirements [14]. In addition, both types of traffic pattern (sporadic and regular) can have normal or critical requirements [15]. Furthermore, they can have distinct types of requirements (e.g., reliability, delay, flow, losses) and different parameters of these requirements (e.g., maximum delay of 1 s, minimum delay of 150 ms) [16]. Moreover, these heterogeneous applications require sharing resources at the same in the network [17]. The smart devices have limited memory, processing power, and reduced battery life which makes IoT scenarios a Low-Power and Lossy Networks (LLNs) [18]. Thus, the Routing over Low-Power and Lossy Networks Working Group (RoLL WG) addresses IoT LLN scenarios which provide solutions that enable communication between smart devices. These devices are connected to each other through multi-hop wireless communication to gather information for multi-applications [19]. RoLL WG standardized the Routing Protocol for Low Power and Lossy Networks (RPL) [20] in which the concept of instances emerged as an alternative solution for dealing with the specificities of multiple applications that coexist in LLNs. Instances virtually divide the network in multiple logical subdivisions, enabling that multiple applications with different classes of Quality of Service (QoS) coexist at the network layer [21; 22]. Each instance can be individually configured to deal with the QoS requirements of a specific kind of traffic. The RFC6550 [20] mentions the possibility of deploying multiple RPL instances. These instances can provide flexibility in routing and enable QoS for multiple applications that coexist in the same scenario. It is important to note that RoLL WG did not specify how to implement multiple instances. For this reason, there is investigation about the development of multiple instances for RPL [21; 22; 23; 24; 25; 26]. However, the proposals present limitations such as:  
* Limiting a single instance per application and no flexibility of instances management. As a result of this, the instances are statics. In other words, it means that each application is associated with a single routing metric and a single interval between application messages throughout the application lifetime on the network, since the applications are associated with a single instance.