# Provisioning of Fog Computing over Named-Data Networking in Dynamic Wireless Mesh Systems
## 3 The Proposed Solutions
### Adaptive Forwarding Strategy
If the probing is not successful, i.e., no Data packet is received over this Face, the negative state of this Face is restored. When the Self-Learning Strategy has to handle a Data packet, it follows the algorithm presented in Figure 7. First, the strategy sends the packet through the available back propagation Face(s) specified in the corresponding PIT entry. Then, it marks the inbound Face positively for the corresponding Name. This Face will then be used in the Interest handling pipeline to forward other Interest packets matching this Name. An example of the forwarding time window dynamics is shown in Figure 8. For a new Name, all Faces are initialized with a predefined time window value, _FValueMaxBase_. This puts each Face into the \"Exploit\" regime, enabling broadcast search over all available Faces. To avoid Faces' \"saturation\" when a chosen Face is utilized for a very long period of time, we limit the forwarding time window using _FValueMax_. The closer the current forwarding value _CurFValue_ to its maximum, specified by _FValueMax_, the smaller the increment due to the successfully received Data packet. The probing time windows for a Face are represented by orange lines in Figure 8. When probing, the period between attempts increases with every unsuccessful attempt until _CurFValue_ reaches the minimum value, specified by _FValueMin_. \begin{table}
\begin{tabular}{l l} \hline
**Label** & **Description** \\ \hline FValue & Forwarding coefficient associated with every available next hop \\ \hline CurFValue & Value of forwarding coefficient at the current moment of time \\ \hline CurTime & Current moment of time \\ \hline FTime & A moment of time when a last Interest with a certain prefix was forwarded via the Face \\ \hline DecayRate & Coefficient regulating change in FValue in time \\ \hline FValueMin & Minimal possible value of FValue \\ \hline FValueMinBase & Starting negative value assigned to FValue when associated Face has entered the explore region \\ \hline FValueMax & Maximal possible value of FValue \\ \hline FValueMaxBase & Starting positive value assigned to FValue when associated Face has entered the exploit region \\ \hline FValueMult & Coefficient regulating change in FValue with every forwarding attempt \\ \hline \end{tabular}
\end{table} 
Table 1: Abbreviations used in the considered self-learning strategy algorithm. With the proposed approach, the Self-Learning Strategy can handle any Interest and Data packets without global knowledge about the network topology, additional internode data exchange, or application configurations. At the same time, the decaying time window utilized by the Self-Learning Strategy can both minimize discovery overhead and handle situations such as link failures or producer re-discovery. The scalability of the proposed solution is ensured by controlling the frequency of flooding. The proposed strategy can also be further optimized to match the requirements of specific scenarios using the following extensions: (i) smart name aggregation into more generic prefixes over time to limit the required memory to store local routing information, (ii) decaying time window size adaptation in real time to account for rapid changes in topology for networking scenarios involving, e.g., nodes mobility, (iii) similarly to [46], \"fish-eye\" flooding can be implemented to limit the number of hops being flooded upon initial discovery. We specifically note that the proposed Self-Learning Strategy is conceptually similar to the self-learning strategy in [37]. However, the proposed strategy attempts to find and maintain all (or at least a set of) possible routes by not only forwarding an interest through the already known route but also by probing other faces. The probe is limited by specific exponential timers attached to each face to limit the network flooding--the fewer successful data receptions one obtains through a given face, the less often one will probe it, while successful reception will increase the lifetime of the route.