## 5 Results and Discussion  
Individual statistics were collected, the simulation was run in two cases (low and high density) and the results were obtained to study the impact of VLAN technology. **Delay and Throughput:** Figure 5 showed the delay and throughput of the network with and without the VLAN and VLAN traffic dropped graph between VLAN 10 and VLAN20. Delay and Throughput indicated how the Virtual LAN could improve the network by reducing the delay and the data dropped, but the throughput was also reduced. VLAN traffic dropped indicated how clients' requests from VLAN 10 to the VLAN 20 server were rejected by \"Switch2\", so that the service was received from the server in their VLAN without any problem, but in VLAN 20, the clients only tried to connect to the server in their VLAN, hence VLAN 20 experienced smaller packet drops than VLAN 10, as shown in Figure 6.  
As seen above, VLAN's primary problem was that it reduced throughput, which is one of the important QoS parameters of any network performance. In this study, the degradation in throughput was improved by using three routing protocols in a low-density network, where the number of workstations was 15 PCs. Figure 7 shows the network delay and throughput with three routing protocols (AODV, DSR and OLSR). Figure 7 indicates that using routing protocols could improve VLANs by reducing the delay of the WLAN and increasing throughput, thus improving the performance of the WLAN. The AODV routing protocols also improved the network by achieving the highest throughput. This study carried out an additional investigation to demonstrate the impact of routing protocols utilization in high-density cases (30 workstations). Delay and throughput in high-density scenarios are shown in Figure 8. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Description** & **Units** \\ \hline \multirow{3}{*}{Traffic Drops} & The number of packets dropped by a bridge that apply the & \multirow{3}{*}{bits/s} \\  & VLAN rules to ignore packets; that is, a packet that is dropped & \\  & when it does not belong to the same VLAN as its destination. & \\ \hline \multirow{3}{*}{Delay} & It represents the time for sending a packet from its source to & \multirow{3}{*}{s} \\  & the destination; this delay includes MAC delay, fragment & \\  & reception delay and frame transfer across the access point if & \\  & access point functionality is enabled. & \\ \hline \multirow{3}{*}{Throughput} & It indicates the number of data packets that can be & \multirow{3}{*}{bits/s} \\  & successfully sent over at a given time from a source to & \\ \cline{1-1}  & destination nodes over a communication channel & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Simulation Parameters. Figure 5: _Cont._  
Figure 5: Delay, Throughput and VLAN Traffic dropped respectively. (**a**) Delay. (**b**) Throughput. (**c**) Traffic Dropped. Figure 6: VLAN Traffic Dropped. Figure 7: Delay and Throughput in Low Density Network (15 workstations). (**a**) Delay. (**b**) Throughput. At high density, all the ad hoc routing protocols reduced the delay and increased the throughput. AODV improved the delay and throughput of the network because it achieved the least delay and highest throughput. Figure 8: Delay and Throughput in High Density Network (30 workstations). (**a**) Delay. (**b**) Throughput. **Traffic Dropped:** At low density, traffic dropped in VLAN 10 and VLAN 20 for three ad hoc routing protocols was compared with VLANs without ad hoc routing protocols to investigate the effect of ad hoc routing protocols on packets dropped, as shown in Figure 9.  
At high density, traffic dropped in VLAN 10 and VLAN 20 for three ad hoc routing protocols was compared with VLAN without ad hoc routing protocols, as shown in Figure 10.  
Figure 9: Traffic Dropped with 15 workstations. **(a)** VLAN 10. **(b)** VLAN 20. As shown in Figures 8 and 9, the routing protocols reduced the VLAN traffic dropped because of the VLAN. Figure 10: Traffic Dropped with 30 workstations. (**a**) VLAN 10. (**b**) VLAN 20.