## 4 End to End Security Analysis on the Proposed IIoT Security Architecture
### Transport Layer
#### 4.2.2 Backhaul Network and Communication Technologies  
The backhaul network, which sits between the capillary and backbone networks, controls circulating data packets. Backhaul network also serves as a bridge in the heterogeneous capillary communication technologies. This section focuses on the analysis of the backhaul networks, which includes ethernet, wireless local area network (WLAN, or Wi-Fi), low rate-wireless personal area network (LR-WPAN), WiMax and universal mobile telecommunications system third generation (UMTS 3G) [96; 97; 98; 99; 100; 101], as presented in Table 8.  
Overall, these communication technologies satisfy the network security requirements, includes the physical and MAC layers security protection, message confidentiality and integrity check, authentication and authorization. However, with limited availability in protection, the strength of their defences countermeasure is varied and strictly dependent on their supported cryptographic algorithms and physical environments, includes the network range and coverage, i.e., WLAN enjoys lower network attack risk compared to WiMax. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline \multirow{2}{*}{**Technology / Standard**} & \multirow{2}{*}{**Features/ Functionalities**} & \multicolumn{5}{c}{**Analysis of Security Requirement**} & \multirow{2}{*}{**Deployed Industry Countermeasure**} & \multirow{2}{*}{**Ongoing Challenges and Future Woks**} \\ \cline{5-8}  & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & \\ \cline{5-8}  & Range: up to 100 m, Mobility: Portable & \(\surd\) & \(\surd\) & \(\surd\) & \(\surd\) & \(\times\) & & & & \\ \cline{5-8}  & Bandwidth: 10 Mbps to 10 Gbps shared & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \cline{5-8}  & & & & & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Security analysis on backhaul network and communication technologies. As most backhaul communication technologies can be applied to support capillary communication (e.g., LR-WPAN) and backbone network (e.g., UMTS 3G and WiMax) in the domain, their role here is more focused on building a bridge or gateway for the data across heterogeneous capillary and backbone networks. Several security challenges need to be further addressed. These include: (i) end-to-end security protection over the bridge between capillary network and backbone networks; (ii) scalability of network size and bandwidth to support the rapid growth of IIoT data packets; (iii) interoperability with existing capillary communication technologies; (iv) stronger but lightweight security mechanisms on a constrained network resource; (v) more sophisticated access control scheme, such as identity-based or attributed-based access control; and (vi) efficient network key management and distribution. Several low power and energy consumption networks have been developed recently to address the resource-constrained issues of IIoT. These works include low power wireless personal area network (6 LoWPAN) and Wi-Fi Halow. Internet Engineering Task Force (IETF) has established a new protocol called IPv6 over low power wireless personal area network (6 LoWPAN) to facilitate the communication between 802.15.4 enabled devices and the Internet. With header compression and address translation technique, IPv6 data packets are encapsulated into 802.15.4 data packets, thus enabling the integration of the 802.15.4 based network with the IPv6 network. Meanwhile, Wi-Fi alliance announced a new extension of Wi-Fi standard-802.11 ah, also known as WiFi-Halow.