# Application-Aware Network Traffic Management in MEC-Integrated Industrial Environments
## 5 SDN-eINP Interplay for Application-Aware Network Traffic Management
### Running Example  
The starting point describes a stationary situation, highlighting two flows from different shop floor subnets (see Figure 4a). An AGV generates a flow (solid orange line) toward the MES, whereas an IIoT device produces another flow (dashed blue line) toward the IIoT manager. Although the running example considers only these two flows explicitly, other flows are expected to traverse the network concurrently. An eINP module performing data aggregation processes the AGV flow as close as possible to its source subnet. Because there are no ENs deployed within the source subnet, data aggregation occurs on \(EN_{C,1}\), as the flow traverses the industrial backbone. At the same time, even the other flow goes through an eINP module. Specifically, the module performs data filtering, by dropping messages of more limited application interest. In this case, the shop floor subnet can exploit an EN; thus, data filtering is performed there.  
Then, the AGV starts moving from one shop floor subnet to another, changing the wifi access point to which it is connected accordingly. As a result, its flow also needs a new path toward the MES. However, an eINP module for data aggregation is not available along the new shortest path (i.e., \(ND_{1}\)-\(ND_{B}\)-\(ND_{A}\)-\(ND_{CR}\)). On the one hand, the flow might go straight to the MES but with no aggregation in place. On the other hand, it might pass through the eINP module for data aggregation but via a longer path. In both cases, there is a waste of network resources. This triggers the IAM, in charge of checking for such harmful communication patterns. Let us assume that the IAM decides to (i) migrate the data filtering module on \(EN_{B,1}\), (ii) steer the IIoT device flow accordingly, (iii) deploy a data encryption module (homomorphic cryptography) on \(EN_{1}\), (iv) deploy a data aggregation module on \(EN_{MEC,1}\), and (v) steer the AGV flow toward the MEC-enabled cell tower through the cellular interface of \(ND_{1}\) (see Figure 4b).  
In this particular example, the IIoT device flow traverses a resource-rich cluster zone along its path (i.e., \(EN_{B,1}\)-\(EN_{B,2}\)). This permits it to scale out and in module replicas dynamically. Because such a flow stresses the single replica available beyond a given threshold, the IAM starts a new module replica in the same cluster zone and thereby balances the incoming traffic accordingly (see Figure 4c).  
Figure 4: Running example of application-aware network traffic management in a MEC-integrated industrial environment. (**a**) Initially, the flows produced by the AGV (solid orange line) and IIoT device (dashed blue line) are processed on-premises. (**b**) Subsequently, the AGV changes to the shop floor subnet. This triggers the IAM, which decides to reconfigure the environment by also taking advantage of the MEC. (**c**) Because the flow produced by the IIoT device traverses a resource-rich cluster zone, additional replicas of the data filtering module are scaled out dynamically to better fit the demand.