g, and QoS control and enforcement functions. We will discuss each of them in the upcoming sections. The transport network The transport network ties each of these network segments together and provides connectivity between them. The transport network can be in various forms, starting from the front-haul - which is generally CPRI- or eCPRI-based and connects the RUs and the DU. Next is the mid-haul, which connects the DU and the CU. This is followed by the back-haul network, which connects the CU to the packet core network. It should be noted that it is of utmost importance that the transport network is fast: it should have low latency and be reliable. This ensures that it is failure-resistant and highly available. It should have the necessary bandwidth to support high data volumes, and it should also be secure and not prone to rogue attacks. As you may have already guessed, the transport network will contain a web of networking gear, such as switches, routers, leased lines, microwaves, optical fibers, and SO on. Hence, based on the requirements, the desired design is selected. The optical front-haul picks up gradually as it provides reliable connectivity and increased bandwidth. Microwaves can be used for relatively long-distance connectivity. Especially in rural and remote areas, solutions involve microwave long-hauls. Since they are cost-effective and easy to deploy, they are a contender as the preferred choice over substitute optical fibers in some cases. In the preceding diagram, you may have noticed that a WAN is used to connect the back-haul network. This is because when a 5G solution is deployed in an entire country spanning thousands of square miles, it is imperative for the service provider network to leverage optical fiber leased lines to transport the user traffic from the operator's 5G network to the internet or content servers. Hence, leased lines or a WAN are used to transport this data. High-level components Data center design In the following diagram, we will go over a sample service provider 5G 