# OPMSS: Optimal Producer Mobility Support Solution for Named Data Networking
## 5 Performance Evaluations
### Numerical Evaluation  
The parameters in Table 1 are used to investigate OPMSS in terms of minimal handoff latency, signaling cost, and path optimization. A numerical evaluation is conducted as in previous research [8; 51] using a network analysis model based on Equations (3)-(14) presented in Section 4.  
The handoff latency is the time it takes a mobile producer to receive a pending interest packet from the content consumer after completion of the handoff. In OPMSS, the time that the _MI_ message takes to update the intermediate FIB tables is measured based on the number of hops between the content consumer and the mobile producer. In the Kite solution, the time taken for the exchange of _TI_ and _TD_ messages between the anchor router or RS and the mobile producer to create traces in the FIB tables, and in addition, the time taken for the pending interest to reach the new location of mobile producer in both PMSS and Kite solution. Figure 6 shows the summary of the numerical handoff latency results for OPMSS and the Kite solution that covered both inter-domain and intra-domain motilities that are measured against wireless link failure. To discuss the intra-domain and inter-domain handoff latency performance of the proposed OPMSS and the Kite solution, observations, justification, a quantitative analysis, and inferences are needed to determine the best solution.  
The handoff latency results are achieved by plotting total handoff latency measured in milliseconds against the probability of the link failure of the mobile producer. Figure 6a shows that OPMSS has 11% lower latency than the Kite solution for intra-domain mobility. The minimum handoff latency is 150 ms for OPMSS and 169 ms for the Kite solution. Furthermore, the handoff latency of OPMSS is less than 20% compared to the Kite solution for inter-domain mobility, with a minimum of 229 ms for OPMSS and 289 ms for the Kite solution. Therefore, OPMSS has better handoff latency performance for both intra- and inter-domain mobility compared to the Kite solution. However, at \(q=0.9\) onward, we can observe that the latency of OPMSS increases by 10% compared to the Kite solution. This is because the Kite solution is able to manipulate the network by keeping the trace update alive. The OPMSS needs to reconnect and broadcast the \(MI\) packet to the domain, because when the link fails, the mobile producer may not be reached. Overall, despite the possibility of total link failure, OPMSS has better handoff latency than the Kite solution.  
The OPMSS solution is implemented in an NDN simulator called ndnSIM that operates based on an open source NS-3. It offers reliable simulation results, particularly for a name-based architecture popularly known as ICN. The ndnSIM allows the transfer of simulated experiments to real practical applications. The simulator is implemented using different C++ programming methods to model NDN architectural behavior, such as the FIB table, CS, PIT, and interfaces of communication with other nodes. The benchmark solution known as TB or the Kite solution is already implemented in ndnSIM, and the codes are available to reproduce the results. The Kite solution is rerun in the same environment with OPMSS to evaluate and compare their performance.  
The operating system used for the simulation implementation of OPMSS is Linux distribution Ubuntu 18.04 LTS, which is open source and compatible with many open source simulators. This is followed by NS-3, a discrete-event network simulator that puts the emphasis on layers 2, 3, and 4. NS-3 is commonly used to model Internet systems and communication networks. NS-3 is integrated with ndnSIM 2.3, and both are configured in Ubuntu 18.04 LTS for a successful simulation experiment.