## 5 Results
### TCP/IP Stack with OLSR vs NDN  
First, we compared the WMN based on the default NDN with a WMN based on the TCP/IP stack running the OLSR protocol. The main objective of this experiment was to investigate whether NDN outperforms the TCP/IP stack in mesh networks. The parameters of OLSR used were the following. The interval between HELLO messages was equal to 1.5 s. Link state messages were sent every 5 s. These messages were used by multipoint relays to calculate the topology map. We assumed traffic with a Constant Bit Rate (CBR) to simulate the request and the delivery of contents in the TCP/IP + OLSR WMN. CBR packets had a size equal to NDN data packets, i.e., 1000 bytes. The goal of this configuration was to approximate the traffic behavior of the two networks, because both networks operate in very different ways regarding data forwarding. Therefore, the CBR traffic was transmitted at the same rate as contents were requested by NDN consumers.  
The TCP/IP + OLSR network is not able to cache popular contents; therefore, we considered contents to be requested sequentially for the sake of a fair comparison. Figure 6 shows the results for the content delivery rate and average delay. We varied the number of consumers between 2 and 30, and varied the rate that each consumer sent content requests between 10 and 50 interests per second. The idea was to investigate the impact of the number of consumers and the rate of content requests in the two WMN deployment approaches. In Figure 5(a), the vertical bars represent the default NDN and TCP/IP + OLSR network for 2 or 30 consumers. Bars are grouped based on the rate of interest sent by consumers, 10 or 50 int/s. The results show that the default NDN delivered more content packets than TCP/IP + OLSR for all analyzed configurations. Furthermore, the performance gap between the two approaches increased as both the number of consumers and the rate of content requests increased. For example, NDN delivered almost 100% of the content packets for two consumers, sending 10 int/s. TCP/IP + OLSR delivered 70% in this configuration. When the number of consumers increased to 30, however, NDN delivered almost 90% of the content packets and TCP/IP + OLSR delivered only 30%.  
We also observed that the delivery rate severely decreased if the content request rate increased to 50 int/s. In this case, the network was saturated, and as a consequence, more packets were lost by medium contention and inter-flow interference. The default NDN performance was still higher than the one provided by TCP/IP + OLSR. This performance is a consequence of proactive caching employed by the default NDN. With proactive caching, nodes store contents sent by other nodes in their transmission range, even if there is no PIT entry for the content. Thus, the content availability increases. With NDN, consumers retrieve contents from adjacent nodes and consequently interest and data packets are forwarded fewer times. Thus, the medium contention is reduced. On the other hand, with TCP/IP + OLSR, packets always traverse the source-destination path.  
In Figure 5(b), it can be observed that the default NDN provided a higher average delay than TCP/IP + OLSR with 30 consumers. In addition, the higher the network saturation was, the higher the average delay was for both approaches. The reason for this behavior is because without the use of a cache, remote nodes on the TCP/IP + OLSR tend to receive fewer packets than NDN. By computing the reception of the contents that have traversed more hops, the average delay is also increased.  
Thus, we conclude that NDN delivers more contents than TCP/IP + OLSR. This increase on content delivery rate, however, has a drawback related to a higher delivery delay. Network saturation is the key point to reduce the content delivery rate and increase the content delivery delay. Therefore, we propose mechanisms to reduce the number of interest packets transmitted and thus, to reduce the network saturation.