# A Novel Framework for Cross-Cluster Scaling in Cloud-Native 5G NextGen Core
## 7 Results Analysis  
In Figure 10a, we measure the AMF service **request throughput** on the outbound interface for the out-of-band peering scenario, which is the traffic captured at the source for the offloaded Open5 GS user plane during the PDU session establishment. We measure a higher maximum throughput for the outgoing AMF request traffic in the offloaded Open5 GS user plane compared to the offloaded Open5 GS control plane shown in Figure 10b. The reason is mainly due to the PDU establishment traffic generated along with the creation of user interfaces, which is done across tenants for the out-of-band peering. Figure 10: _Cont._  
Figure 9: VPN configuration for in-band peering. In Figure 10, we can also observe that the AMF maximum **request throughput** on the outgoing interface for the offloaded control plane is twice the **response throughput** value measured at the destination for the same scenario displayed in Figure 10c. For both source and destination outbound traffic, the peak values for the request throughput are generated by the SMF that requires the performance of an AMF selection. The same set of measurements is obtained for the SMF response and request throughput for both out-of-band peering scenarios. The maximum **request throughput** for the SMF service on the outbound destination for the Open5 GS offloaded control plane (Figure 11b) is three times higher than in the case of the offloaded user plane; see Figure 11a. On the other hand, for the **response throughput** at the source in the case of the offloaded user  
Figure 10: Request throughput on AMF for the out-of-band peering scenario. (**a**) Request throughput on AMF source for offloaded user plane. (**b**) Request throughput on AMF outbound source for offloaded control plane. (**c**) Response throughput on AMF destination for offloaded control plane. plane on the remote cluster displayed in Figure 11c, we register half the value of the **request throughput** measured at the destination for the same scenario (see Figure 11a). In Figure 12, we display the latency expressed in milliseconds for each of the user plane functions in the out-of-band scenario where two UPFs are offloaded to the remote cluster. To measure the latency, we used the _ping_ tool that gives us the round trip time (RTT) of transactions [77]. Ping uses ICMP packets; for instance, for an interval of 10 ms, ping sends one ICMP packet per second to the specified IP address until it has sent 100 packets. Figure 11: _Cont._  
In the out-of-band scenario, we observe that the latency for UPF1, which represents the user plane running on the local cluster, is smaller (around 1 ms) in comparison to the other two user functions hosted on the remote cluster, where the latency is above 2 ms as displayed in Figure 12. In the case of the in-band peering, the values in terms of latency for the three UPF functions are similar since the user plane traffic between the two clusters is flowing through the VPN tunnel (see Figure 13).The end-to-end latency when we ping google.com (accessed on 9 April 2024) is displayed in both Figures 14 and 15. In both out-of-band and in-band peering scenarios, the registered end-to-end latency is around 11 ms for all three network slices when running simultaneously 10 user connections for each network slice. Since the obtained values for end-to-end latency measured for all three user plane functions are less than 100 ms when running all 30 user connections, a wide range of vertical use cases can be covered, from streaming to smart energy applications. Figure 11: Request throughput on SMF for the out-of-band peering scenario. (**a**) Request throughput on SMF destination for offloaded user plane. (**b**) Request throughput on SMF destination for offloaded control plane. (**c**) Response throughput on SMF source for offloaded user plane. Figure 12: User plane latency for out-of-band peering scenario. Figure 14: End-to-end user latency for different slices in the out-of-band peering scenario. Figure 13: User plane latency for in-band peering scenario.