# A New Bit Repair Fast Reroute Mechanism for Smart Sensors IoT Network Infrastructure
## 5 Conclusions  
The paper presents the bit-repair (B-REP) FRR mechanism, which provides advanced fast reroute solutions for IoT and IP network infrastructures. B-REP uses a standardized BIER header with a special bit-string field. That allows us to use a standardized header and its fields to define an alternative path as well as to transfer user data. The bit-string, in addition, allows us to efficiently define an exact alternative FRR path, which can be calculated by the Dijkstra algorithm or even manually defined by the administrator. Some existing mechanisms, such as LFA or remote LFA calculate an alternative path according to specific metric conditions. However, in topologies with inappropriate metrics, these mechanisms are not able to choose an alternative path, but our algorithm is. We also add the ability to ignore metric-based calculations in our proposal, allowing us to select any possible physical alternative \begin{table}
\begin{tabular}{c c} \hline \hline
**Advantages** & **Disadvantages** \\ \hline Suitable for networks of any size & Pre-computation \\ Applicable for a link-state routing protocol & Encapsulation packet overhead \\
100\% repair coverage & \\ Possibility to define a custom path & \\ Relatively easy implementation (Bit-String) & \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Properties of the B-REP algorithm. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Title** & \begin{tabular}{c} **100\% Repair** \\ **Coverage** \\ \end{tabular} & \
\begin{tabular}{c} **Custom** \\ **Alternative Path** \\ \end{tabular} & **Precomputing** &
\begin{tabular}{c} **Packet** \\ **Modification** \\ \end{tabular} \\ \hline B-REP & Yes & Yes & Yes & Yes \\ EM-REP & Yes & No & No & Yes \\ ECMP FRR & No & No & Yes & No \\ BIER-TE (M) & Yes & No & Yes & Yes \\ Directed LFA & Yes & Yes & Yes & Yes \\ LFA & No & No & Yes & No \\ MPLS-TE FRR & No & Yes & Yes & Yes \\ MRC & Yes & Yes & Yes & Yes \\ MRT & Yes & No & Yes & Yes \\ Not-Via & Yes & No & Yes & Yes \\ Addresses & Yes & No & Yes & Yes \\ Remote LFA & No & No & Yes & Yes \\ TI-LFA & Yes & No & Yes & Yes \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Comparison of the B-REP mechanism with existing solutions. path. This mechanism can provide link or node protection and is suitable for any link-state protocols. These properties of the B-REP algorithm make it possible to achieve full repair coverage, which provides the protection against all possible failures in the network if a physically alternative path is presented. The B-REP mechanism, as a proactive FRR mechanism, shares with other FRR mechanisms the properties of this family, which are identified as limitations. This includes CPU consumption during preliminary calculations and memory consumption for storing them. With FRR mechanisms that create a remote alternate path, B-REP uses the encapsulation of the original packets, which of course increases the overhead of the transmitted data. However, this limitation is partially addressed by using the Bit-String to define the entire transmission path. The speed of existing proactive FRR mechanisms including B-REP is similar, but the differences are in the way how they calculate alternative FRR path, how effective the results are and how the alternative path is constructed. According to our research, there is no FRR mechanism of all solutions. All of them have some advantages and disadvantages and B-REP brings his perspective on the solution to the issue. The B-REP mechanism was fully implemented, and its correctness was tested using the OMNeT++ discrete event simulator. We have performed various extensive tests of the implementation in different network topologies, which validated the functional correctness of all B-REP sides. The use of Bit-String is unique, and it is possible to apply it in WSN networks, IoT design, and other areas as well, which will be studied in future work.