# Fault Tolerant DHT-Based Routing in MANET
## 5 Simulation and Results Analysis  
We implement FTDN in an open-source discrete event simulator, i.e., NS-2(2.34) [27] to evaluate the performance. Network parameters are tuned to standard values for both physical layer and link layer to simulate IEEE 802.11 along with a two-ray ground propagation model. The key objective is to create a contention-based MAC environment that best suits routing protocols in MANETs. Moreover, Constant Bit Rate (CBR) is used as a data traffic model over a user datagram protocol, and a random traffic model is used as a data pattern.  
Similarly, to avoid packet drops due to congestion in the multi-hop approach, the global traffic load is kept constant at 64 pkts/s. Likewise, mobility is another influential factor in the performance evaluation of routing protocols in MANET. Mobility compromises network connectivity (links) and is directly associated with network dynamics (nodes/links failures, network partition, merging, etc.). Mobility scenarios, based on random waypoint model, are created using BonnMotion2 [28], with nodes moving speed 0.5, 1.0, 1.5 and 2.0 (m/s) for different network sizes ( 50, 100, 150, 200). BonnMotion2 [28] ensures physical network partitioning and maintains network partitions, etc., records. Moreover, FTDN uses DART [14] routing mechanism in the implementation. The simulation parameters are listed in Table 2.  
Performance comparisons have been made using following metrics with varying network size and speed.  
* Lookup-Success Ratio (LSR): It is the ratio between total lookup queries (i.e., mapping request packets (MREQ) ) and the total lookup queries resolved successfully (i.e., total MREQ successfully entertained by receiving mapping reply (MREP)). LSR is measured using Equation (1). Lookup Success Ratio(LSR) = \[\frac{\text{Total LookupRequests Initiated}}{\text{lookup Requests Successfully entertained}}\] (1)
* End-to-End Lookup Delay: The average time taken by a lookup query to get resolved. In other words, the average time elapsed between MREQ and MREP encountered by a source node. It includes route discovery delay and queuing delay. It is measured in seconds. The E2E lookup delay is calculated using Equation (2). End to End (E2E) Lookup Delay = \[\frac{\text{Total Lookup Delay}}{\text{lookup Requests Successfully entertained}}\] (2)
* Normalized Overhead: It is the ratio between total number of transmission at the network layer and total number of lookup queries successfully resolved (i.e., total number of MREQ for which MREP is received). Normalized Overhead = \[\frac{\text{No. of Transmissions at Network Layer}}{\text{ Lookup Requests Successfully entertained}}\] (3)  
Normalized overhead is an important metric to measure total routing overhead per successful lookup query. The normalized overhead per lookup request is measured using Equation (3).  
\begin{table}
\begin{tabular}{l l} \hline \hline
**Parameters** & **Values** \\ \hline No. of Nodes & [50, 100, 150, 200] \\ Radio range & 100 m \\ Network area & 1000 m \(\times\) 1000 m \\ Data rate & 64 pps \\ Simulation time & 500 s \\ Speed & [0.5, 1.0, 1.5, 2 (m/s)] \\ Topology Connectivity/Generation & BonnMotion2 \\ Propagation Model & Tow-Ray Ground \\ Avg. no. of network partitioning & 5 times \\ No. of flows & 12 \\ Traffic Model & Random Traffic pattern \\ Routing Protocols & DART \\ Mobility Model & Random way point \\ \hline \hline \end{tabular}
\end{table}
Table 2: Simulation Parameters.