## 4 Classification of Routing-Related Surveys
### Medium Focused Areas
#### 4.2.1 Security Based Routing Surveys  
The security based routing surveys discuss those protocols which may carry out threat prevention, intrusion detection or hybrid approach for dealing with various security threats (such as selective forwarding, hello-flood attacks, wormhole attacks, sinkhole attacks, sybil attacks, acknowledgment spoofing, neglect and greed attacks (Denial of Service (DoS)-based)) and accomplishing various basic security objectives (such as confidentiality, integrity, availability, authentication [45] and freshness of data). According to the nature of underlying security surveys for WSNs, they may be classified into four categories as discussed below:  
1. In multipath based categorization, the classification metric is based on threat prevention, intrusion detection, hybrid or cryptographic, key management, authentication scheme and basic security requirements. 2. In hierarchical based categorization, cluster-based protocols are classified on the basis of security goals, selection of security mechanism and prevention of security threats oriented requirements and objectives. 3. In typical based categorization, the secure routing protocols are differentiated on the basis of key design issues such as node deployment, energy consumption, data-reporting model, fault-tolerance, scalability, robustness, load-management, data aggregation and QoS. 4. In partial secure categorization, those surveys are delineated which, apart from mainly focusing on security, also discuss routing in WSNs. Such a security oriented routing is termed as secure routing. Considering the surveys with complete emphasis on routing, the authors in [59; 65; 96], and [72; 78] have mainly classified routing protocols into multipath, and hierarchical based secure categorization respectively. In [40; 45; 84], the authors have classified routing protocols into security based typical categorization. The authors in [78] devise a metric that may determine fitness of different protocols to suitable WSNs applications. The authors in [45; 59] have put forth threat model while [40] employs key design issues of routing in WSNs that may help to compare secure multipath routing protocols. The threat model proposed in [59] is helpful in identifying the intentions and schemes of antagonist and the security issues in routing process. Such identifications may help the protocol designers to address them in a proper manner. However the survey does not provide any clear-cut and methodological \begin{table}
\begin{tabular}{l l l} \hline \hline \multicolumn{1}{c}{**Survey Type**} & \multicolumn{2}{c}{**Categorization and Design Requirements Based Analysis of Secure Routing Surveys**} \\ \hline \multirow{2}{*}{**Multipath based**} & _Hg_ & [59] \\ \cline{2-3}  & _Md_ & [65; 96] \\ \hline \multirow{2}{*}{**Hierarchical based**} & _Md_ & [72; 78] \\ \hline \multirow{2}{*}{**Typical based**} & _Hg_ & [40] \\ \cline{2-3}  & _Md_ & [84] \\ \cline{2-3}  & _Lw_ & [45] \\ \hline \multirow{2}{*}{**Partial based**} & _Hg_ & [119; 127] \\ \cline{2-3}  & _Md_ & [116; 118; 130; 131; 138] \\ \cline{2-3}  & _Lw_ & [122; 129] \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Design analysis of secure routing surveys in WSNs. framework like [41] that is helpful in _state-of-the-art_ secure multipath routing protocols in WSNs. The surveys in [40; 65; 72; 78; 84; 96] have discussed security issues and requirements of WSNs. Future research directions are outlined in [40; 59; 84]. Furthermore, Table 7 figures out that this classification includes only 2 high count, 5 medium count and 1 low count surveys. The surveys having partial emphasis on secure routing consist of [116; 118; 119; 122; 127; 129; 130; 131; 138]. The authors in [116; 118; 119; 122; 127; 129; 130; 131; 138] have discussed some aspects of secure routing and therefore, such surveys are classified into security based partial categorization. The authors in [129; 130; 131; 138] have discussed attacks and counter measures at different layers of communication protocol stack including network layer.