# Dynamic QoS Management for a Flexible 5G/6G Network Core: A Step toward a Higher Programability
## 5 Testbed Design
### Methodology Implementation
The problem of congestion can be immediately noticed by analyzing the responses of WEB requests because large-size responses can not finish in less than one second. Instead, the packet transmission must be redistributed over time. The available bandwidth has been redistributed according to the policies in the SQL table and the proposed bandwidth allocation mechanism. We allocate a bandwidth of 1 Mbps for the SEC service, 6 Mbps for the MM service, and 3 Mbps for the WEB service. SEC and MM services have higher priority than the WEB service. Therefore, the WEB service receives the remaining (available) bandwidth (less than required by the prescribed policy). According to the policy, the only visible change in upload direction is SEC service bandwidth reduction. The results obtained by testing in Scenario 4 indicate the effects of a dynamic change in QoS policy. The dynamic change of SQL policy has led to a change in service priorities, and the WEB service obtains the highest priority in resource allocation. In the download direction for the WEB and MM services, we allocate 4 Mbps, and we allocate 2 Mbps to the SEC service, following QoS policies. However, bandwidth allocation was completed according to service priorities in the upload direction. A total of 1.2 Mbps has been allocated for the WEB service, which has the highest priority, while 3.5 Mbps has been allocated for the SEC service. The remaining bandwidth is allocated to the MM service (less than defined in the QoS policy). Scenario 5 shows a situation in which one of the services is no longer in use, so it is possible to perform a dynamic reallocation of freed resources to give active service groups a higher bandwidth and, thus, improve the services' performances. In our example (the bandwidth previously allocated by the QoS policy for the MM service), we can now reallocate for remaining services, which immediately shows the increased number of transactions. This scenario shows that it is possible to delete queues for service groups that are no longer needed. Reducing bandwidth below the level required by the services leads to a reduction in the performance of that service. Figure 10 shows the impact of congestion and the application of QoS policies on the performance of individual service groups. As we can observe, Figure 10 clearly shows that the limitation of the SEC service group upload in Scenario 3 introduces significant delay and packet drops. The service group requires up to 3.2 Mbps (Table 1), but the QoS policy allocates 2.5 Mbps. Therefore, when the queues are filled, all future packages from this service group are dropped. A similar case is with the MM service, where traffic is generated with exponential distribution up to 6.2 Mbps, but the download link is only 6 Mbps. Figure 10: QoS parameters during testing. Further, Scenario 4 introduces even more reduction in the bandwidth of the MM service group (4 Mbps for download link), which results in a considerable delay and packet drops. However, this is an indicator of poor service performance for this streaming service. However, even application services that use UDP streaming often have some mechanisms for dynamic reduction in transmission throughput. For example, video streaming services use the possibility of a dynamic bitrate. When the client notices the link degradation and packet loss, it can ask the server to reduce bitrate (i.e., reduce the quality of the video stream until the packet loss is eliminated). Our testing scenario did not include such a bitrate reduction concept. We can notice that the SEC service group in Scenarios 4 and 5 did not recover the congestion introduced in Scenario 3. ## 7 Conclusions

Network slicing has an essential role in research aiming to develop new concepts of flexible network architecture. The current level of maturity and the constant development and improvement of this technology point out that network slicing will soon become a network standard and play a vital role in future network designs and operations.