# Efficient Secure Routing Mechanisms for the Low-Powered IoT Network: A Literature Review
## 4 IoT-LPN Protocols  
Several routing protocols have been developed to improve the efficiency and functionality of networks in IoT systems. Low-powered protocols have been prevalent in the demand for low-powered IoT frameworks as they are efficient and require fewer resources, making them practical and providing many benefits. Table 1 shows the most efficient and popular low-powered and LLN protocols; here, the protocols are characterized by their foundational, low-powered protocols, including RPL, GOAF, LOADng, SMRF Smart-Hop, and SPEED. GeoRank aims to improve P2P functionality and minimize the number of control messages needed, but it reduces scalability and requires static nodes or GPS-enabled devices. Further, the protocols are mapped with the routing solutions they present, which are P2P support, multicast communication, mobile node support, Quality of Service QoS, and energy efficiency. Table 1 briefly describes each protocol and states its strengths and limitations. The limitations of each protocol highlight grey areas that need attention for improvements. Energy-efficient region-based RPL (ER-RPL) is designed to prevent the network from flooding with peer-to-peer (P2P) route-finding packets, resulting in energy savings and an increase in the P2P packet delivery ratio. P2P-RPL allows for the construction of alternative P2P routes for application routing needs, but it increases the overheads and energy consumption of the network. Bidirectional multicast RPL forwarding (BMRF) improves both upstream and downstream multicast data forwarding. Still, it has a slight increase in memory consumption and can have low productivity due to end-to-end latency and incorrect parameter settings. Stateless Multicast RPL Forwarding SMRF improves RPL's multicast data forwarding and reduces energy waste but only allows for downward multicast broadcasting and can have high end-to-end latency. mRPL provides quick and reliable mobility support in RPL but increases the length of control messages and the number of control messages sent and received. Backpressure RPL (BRPL) aims to improve RPL's performance in large-scale networks, but it requires a large amount of memory and has a high end-to-end latency. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Protocol** & **Foundation** & **Routing Solution** & **Description** & **Strengths** & **Limitations** \\ \hline ER-RPL [28] & RPL & P2P support & ER-RPL prevents the whole network from flooding with lowering network energy usage. Furthermore, the technique enables the transmission of P2P messages and utilizes the structure produced by default RPL for various traffic patterns. & It prevents the whole network from flooding with P2P control messages, resulting in significant energy savings and an increase in the P2P packet delivery ratio. & Some location-aware nodes are required (e.g., GPS) to have a complex strategy; additional control messages are added in addition to the essential RPL messages. \\ \hline P2P-RPL & RPL & P2P support & P2P support & Allows for constructing alternative P2P & Increases the overheads and energy application routing & Consumption of the network by using a root node for P2P message & Flooding it with control packets. \\ \hline P2P-RPL [29; 30] & RPL & P2P support & P2P support & Allows for constructing alternative P2P & Increases the overheads and energy application routing & Increases the overheads and energy consumption of the network by using a root node for P2P message & Flooding it with control packets. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Effective low-powered and LLN protocols in IoT frameworks.