# Neighbor Session Solutions for Integrated Routing Protocols
## 4 Modeling Protocol Integration Solution Classes
### PISC 3--L3 Transport, Multiple Adjacencies
#### 4.1.1 Sending Part
As we can see, the time criterion is very suitable for comparing, for example, two implementations of the same routing protocol. Still, it is not general enough to compare generic PISC. As another possible criterion for comparing models, the number of places or transitions intuitively comes to mind. The problem with this criterion, however, is the fact that we discover, based on the literature analysis, that some places or transitions can be used in the model due to the limitations of the modeling language. We can also illustrate the problem based on our experience modeling the receiving part of the fourth grade model shown in the Figure 5.5 It is necessary to create separate Decapsulate IPv4 and Decapsulate IPv6 transitions to decapsulate IP packets because the modeling language does not allow the processing of two different elements of the union structure on the same edge. Since it is not possible to simultaneously \"retype\" and compare individual sub-items of the \"retyped\" color. The third criterion considered is a comparison based on the number of simulation steps required to establish adjacency between routers and transfer routing information. One simulation step represents one pass through the model. This criterion could be considered a generalization of the time criterion since it does not depend on the specific implementation of the model, but only on the execution of the model itself. Since the models of all four classes are created to reflect the individual significant differences of each class and the inevitable variations of services supporting the establishment of adjacency and the exchange of routing information, and the rest of the model is the same, we can \begin{table}
\begin{tabular}{l c c c} \hline
**Model** & **Nodes** & **Arcs** & **Dead Markings** \\ \hline PISC 1 & 21,787 & 42,190 & 21,765; 21,772; 21,787 \\ PISC 2 & 91 & 90 & 91 \\ PISC 3 & 40,897 & 78,468 & 40,864; 40,873; 40,897 \\ PISC 4 & 1382 & 2408 & 1381; 1382 \\ \hline \end{tabular}
\end{table} 
Table 1: PISC models’ state space statistics comparison. consider the criterion of the number of simulation steps to be appropriate and also general enough to compare the models and subsequent establishment of recommendations for the design of integrated routing protocols. Since the selected comparison criterion (number of simulation steps) depends on the method of model execution, the conditional step is the verification of individual models, which is described in Section 5. By calculating the state space, we find that the execution of some models may end up in different nodes of the state space, so we assume that the number of simulation steps may also differ in different simulation runs of the same model. Therefore, we decide to perform a larger number of replications of the simulation run (1000 replications in our case). CPN Tools allows you to run multiple replications of an automatic simulation by defining the following:

CPN'Replications.nreplications 1000

while the result is a text output listing information about each simulation run. An example of part of the simulation output of the first two replications of the first PISC model is shown in Figure 16.

Important items of the output of each simulation run are the simulation number (Simulation no. ), the number of steps after which the simulation ended (Steps), and the reason for ending the simulation (Stop reason). Since there is a larger number of simulation runs of individual models, to be able to compare them collectively, we decide to use the statistical functions arithmetic mean and mode so that the resulting statistics show the most frequent number of simulation steps as well as the effect of all runs on the resulting number of simulation steps. The results are summarized in Table 2.

As we can see from the results in Table 2, the number of steps of all simulation runs is the same for the second, third, and fourth classes, indicating the same median and arithmetic mean.