## 5 Evaluation
### Simulation Tests  
All of the simulation tests were performed on an IBM-compatible PC with an Intel Atom(r) 1.6 GHz processor, running Debian GNU/Linux OS with a g++ compiler and OMNeT++ v4.1 [43]. We used four different network topologies (Net5, Net10, Fish, and Extended Fish), which are represented in Figure 6. These network topologies were selected in order to be able to analyze the effect of congestion due either to network size or to the presence of bottlenecks. The Net5 and Fish topologies correspond to small networks (five and six nodes respectively) while Net10 and Extended Fish topologies define relatively bigger networks (10 and 11 nodes respectively). Every node in Net5 and Net10 is well communicated (almost full-mesh topologies), while Fish and Extended Fish topologies involve significant bottlenecks. The experiment considered relatively small networks, but it was enough to provide important information about the effect of network congestion due to network size and the presence of bottlenecks. We expect that the effect would be magnified if more nodes were used in further experiments, that could also be used to provide information about scalability. A high volume of traffic (Figure 7) was generated automatically. In order to promote network congestion, we concentrated all the generated traffic in just three destination nodes. Figure 6: Network topologies used in the experiments. All simulation tests were limited to 100 s.  
The main idea in the first experiment was to obtain preliminary numbers about the lengths of the queues in the nodes and the average time in each queue, to determine the opportunity for PIN, which is calculated by multiplying the number of queued packets (qlen count) times the average queueing time (qlen time avg). The results are graphically presented in Figure 8.  
Figure 8: Opportunity for PIN (in seconds, logarithmic scale). Figure 7: Characteristics of the traffic that was injected. It should be noticed that opportunity for PIN increases with the network size (comparing Net10 to Net5, and Extended Fish to Fish) and with the presence of bottlenecks (comparing Fish and Extended Fish to Net5 and Net10). This opportunity for the PIN number indicates how many packets and for how long they stay in the queues. This scenario means that it is possible to perform processing during that time. This first experiment is useful for determining how many packets there are and how much time they stay in the queues and, therefore, the packets that are susceptible to being processed in the network. The actual network processing opportunity will depend not only on the fact that a certain amount of packets are in the queues but also on the real process capacity that is available at each intermediate node, which could be used to process the queued packets while they are waiting to be transmitted. For the second experiment, we wrote some simulation code to demonstrate the PIN feasibility, specifically for the functionalities of pre-processing and information simplification on a packet-to-packet basis. To validate these functionalities, three corresponding indexes were defined. * The Pre-Processing index (PP index) was expressed as a percentage. A reference value of 0% means that no pre-processing was performed by the network. A value of 100% means that information arrives completely processed;
* The Simplification-of-Information index (SI index) is expressed as a percentage and is calculated as a function of the total size (expressed in kbps) of the original information that is to be transmitted from the source node. The reference value is 0%, which means that the complete information is transmitted in the network. A value close to 100% means that information is simplified maximally, and therefore, almost none of it is transmitted over the network;
* The Information-Enrichment index (IE index) is expressed as a percentage. It is calculated as a function of the total original content of the information in the original message.