## 4 Proposed LOADng Enhancement for IoT Networks
### Internet Route Discovery Process  
The Internet route discovery should always be initiated when a node does not find a route entry to an IN on its Routing Set. Thus, the node should create an RREQ with the flag iot set as TRUE (hereafter, this message is named RREQ-IoT). Then, the node defines its own address as the RREQ-IoT originator and destination, and a set new unique seq-num. In the following, the node should consult its IRC (if in use) to verify the existence of a previously known Internet route. At this point, the IRC is considered to be empty, and will be explored in the next subsection. Thus, the node should transmit the generated RREQ-IoT in a broadcast to its neighbors. Each node that receives an RREQ-IoT should perform its processing according to the flowchart in Figure 3. Thus, the node first checks whether the message is valid for handling and then conducts the common message processing. The common message processing is done in a similar way as in the standard RREQ message and following the flowchart in Figure 2c. Additionally, during this processing, at the moment a new entry is created in the Routing Set, the node should include the information about the Internet connection status of the message originator. As the RREQ-IoT message originator does not have an Internet connection, the route entry that was created based on the received RREQ-IoT should have the R_Internet_conn set as FALSE. In addition, if the received RREQ-IoT is used to update the \begin{table}
\begin{tabular}{c c} \hline \hline
**Internet Route Cache** & \\ \hline
**Field** & **Description** \\ \hline RC\_dest\_addrr & Specifies the address of the destination removed from the Routing Set \\ RC\_next\_hop\_addrr & Specifies the address of the next hop to reach the destination \\  & removed from the Routing Set \\ \hline
**Configuration Parameters** & \\ \hline
**Field** & **Description** \\ \hline R\_INTERNET\_HOLD\_TIME & Defines a valid time to an Internet route entry in the Routing Set \\ USE\_INTERNET\_ROUTE\_CACHE & Specifies if the node uses the IRC mechanism \\ NUM\_ROUTE\_CACHE\_ENTRIES & Indicates the number of entries supported in the IRC \\ \hline
**Error Code** & \\ \hline
**Field** & **Description** \\ \hline INTERNET\_CONN\_LOST & Indicates the impossibility of forwarding a data message to the Internet \\  & due to lost; the error code is 253. \\ \hline \hline \end{tabular}
\end{table} 
Table 4: LOADng-IoT new features. \begin{table}
\begin{tabular}{c c} \hline \hline
**RREQ and RREP** & \\ \hline
**Field** & **Description** \\ \hline
**iot** & Indicates that the RREQ or RREP message is *-IoT; when used in RREQ, \\  & indicates that the originator is searching for an Internet node; when used \\  & in RREP, indicates that the originator has an Internet connection. \\ \hline
**Routing Set** & \\ \hline
**Field** & **Description** \\ \hline R\_Internet\_conn & Indicates the address of the blacklisted neighbor \\ \hline \hline \end{tabular}
\end{table} 
Table 3: LOADng-IoT required increments in to LOADng structure. information on an existing route entry, the R_Internet_conn should never be changed to false. If the common processing is concluded without the message being dropped, the message handling proceeds to the next step. Thus, in the specific RREQ-IoT processing, the node should check whether it has an active Internet connection (the information on whether or not the node has an Internet connection can be obtained in several ways; this work does not mandate a specific way of doing this. However, as a suggestion, the routing layer can be informed about the Internet connection status through the application layer.). If the node identifies an active Internet connection, it should reply to the RREQ-IoT by generating and transmitting an RREP-IoT message to the request originator. However, if the node does not have an Internet connection, it should check whether the message is valid for forwarding. If true, the node searches for an Internet route on its Routing Set.