to achieve this download rate. It's a quasi arbitrary number, but typical rates range in the 10-50 range. Assume for our DU example to have roughly 1000 connected users per Cell Chapter 3 Hardware system dimensioning 107 Mbps/busy hour per (Mobile) Person in N.A. FIGURE 3-5 Dimension to busy hour (mobile). Site DU (a rule-of-thumb global average from the 4G (LTE) days), we can now calculate the required Cell Site throughput as: 10 Mbps X 1000 users/20 (chosen oversubscription ratio) = 500 Mbps. This would be the capacity that the Cell Site base station needs to support towards the CU link and can be used to dimension specifically Layer 2 stack performance needs, for the Physical Layer components, dimensioning to average is much more complex given the real time constraints that the physical layer is under. Note how the oversubscription ratio can be correlated to the previously discussed Mbps/ "busy hour" value. If we take (2020) a Mbps/"busy hour" of 0.6 Mbps and a desired con- sumer "experienced" data rate of 10Mbps, the oversubscription rate is 10/0.6 17x. This shows how the two techniques (top-down and bottom-up) end up matching. Elephant flows An elephant flow is defined as a high bandwidth connection that is typically transmission control protocol based. This type of flow could correspond to a user downloading a huge file or similar operation. The characteristics of this flow is that it is a very high bandwidth, over a short amount of physical time. What makes an Elephant Flow unique is that it poses specific challenges on the underly- ing hardware implementation. Let's explain this in a bit more detail. Modern hardware implementations for high-bandwidth telecommunications products rely on parallelization to implement high-performance systems where there is more than a single processing element doing each function (say, encryption, classification, and so on). In this type of implementa- tion, the incoming traffic is directed to one of the multiple cores, accelerators, or other pro- cessing elements to spread 