# A Design for SDN-Based Identifier-Locator Separation Architecture on IoT Networks
## 3 Proposed SDN-Based Identifier-Locator Separation Architecture for IoT Networks
### Main Procedure
#### 3.4.2 Route Optimization Process
## 5 Results

For the comparison between MOFI and the proposed scheme, we evaluated the costs of signaling and packet forwarding based on the cost model illustrated in Figure 4. The packet lengths used in the evaluation and some system parameters are shown in Table 1. All the packet lengths include the upper layers of the network layer. OpenFlow messages are delivered using Transmission Control Protocol (TCP), so 60 bytes of TCP Ack size are involved in the packet lengths. Figure 5 shows the comparison result for the signaling and packet forwarding cost of MOFI and the proposed scheme according to the change in the hop count and the session length. For example, the packet delivery cost in MOFI is calculated with Equation (24). The session length is calculated from the number of data processed per second. When the size of the data packet is large, the session length is also increased. Data that can be processed in one session were calculated by multiplying the packet length by the number of packets. Therefore, the packet delivery cost of the MOFI for the 10 packets can be calculated according to Equation (24) as follows:

\[C_{PD}^{M}=10*(\text{L}_{DP}+\text{L}_{LH})*(2*\text{hops between AR and node}+\text{hops between ARs})=5,200\]

In the case of the proposed scheme, the packet delivery cost for 10 packets can be calculated according to Equations (25) to (29) as follows:

\[ \begin{array}{l}C_{PD}^{New}=C_{FPD}^{New}+C_{ODF}^{New}\\ =(r_{no}*10*L_{DP}(2*\text{hops between AR and node}*2*\text{hops between ARs}))\\ +((1-r_{no})*10*L_{DP}(2*\text{hops between AR and node}+\text{hops between ARs}))\\ +\text{hops between AR and node}*\left(\text{L}_{fPIN}+L_{FMOD}+L_{fPOUT}\right)\\ +\text{hops between AR and node}*\left(\text{hops between ARs}-1\right)\\ \ast\left(L_{fPIN}+L_{FMOD}+L_{fPOUT}\right)=5,820\end{array} \]

In this case, the packet delivery ratio that uses an suboptimal path (\(r_{no}\)) was set to 0.1. As a result, packet delivery costs according to 10, 20, 30, and 40 packets were calculated as 5200, 10400, 15600, and 20800 in MOFI, whereas, the costs in the proposed scheme were calculated as 5820, 9468, 13116, and 16764, respectively. Figure 4(b) shows the result that was calculated in MOFI and the proposed scheme. The signaling cost could be calculated through the same process, and the result is shown in Figure 4(a). As shown in Figure 4(a), the signaling cost of the proposed scheme was higher than MOFI. In the proposed scheme, the OpenFlow messages in the EID domain are exchanged between ARs and OFSs, so it is reasonable that the proposed scheme always generates a higher cost than MOFI. In MOFI, the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Notation** & **Size (bytes)** & **Notation** & **Size (bytes)** & **Notation** & **Size (bytes)** \\ \hline L\({}_{BR}\) & 88 & L\({}_{RPOUT}\) & 246 & L\({}_{ROR}\) & 88 \\ L\({}_{LQR}\) & 88 & L\({}_{RPOUT}\) & 246 & L\({}_{fPOUT}\) & 334 \\ L\({}_{RR}\) & 88 & L\({}_{ROPOUT}\) & 246 & L\({}_{LH}\) & 40 \\ L\({}_{RP}\) & 88 & L\({}_{ROPOUT}\) & 246 & L\({}_{DP}\) & 64 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Parameters and packet size. Figure 5: Comparison between Mobile Oriented Future Internet (MOFI) vs. proposed scheme: (a) signaling cost comparison; (b) packet forwarding cost comparison. communication cost between the LMC and the AR does not appear because the LMC is located in the AR. To compare packet delivery cost between MOFI and the proposed scheme, we established the number of hops between the OFSs (ARs) as 5. The session length was calculated by the multiplying packet length (LDP) by the number of packets N(p) and changed from 0.64 to 12.8 Kbytes. In contrast to the signaling cost, the proposed scheme showed a better result. Figure 5b describes the difference in terms of packet forwarding cost between MOFI and the proposed scheme. As shown in Figure 5b, the gap of the linear graphs of MOFI and this scheme was greater as the increase of session length.