lure of any critical link or node 3. Protected network resources and network domain communications, in order to block any unintended access and cryptographically protect communications on links 4. A culture of consistently documenting, following, and enforcing sound design prin- ciples Against all the diverse needs and different cases, a range of physical media and net- working technologies and solutions exist, and those need to be assessed against the intended target state, with a time scope of at least some years ahead. 9.1.2 Types of 5G Transport The majority of the sub-6-GHzmacro-gNBs will be deployed to the same site as LTE. It is possible to use the existing LTE transport if the capacity is sufficient, but quite often the 9.1 5G Transport Network transport capacity need to be upgraded, for example, from 1 Gbps to 10 Gbps. Copper or microwave radios (MWRs) need to be changed to fiber or millimeter wave radios for more bandwidth. Small cells are needed to add a capacity layer under the macro base stations. A new transport link is needed for the new cells. If the target is not to increase capacity but to fill coverage holes, Integrated Access and Backhaul (IAB) may be used. Small cells using mmW frequency have a very small cell size. A completely new and dense transport network is needed. Those gNBs that are not in the hottest spots may use IAB. IAB is a connection without any cost, but it consumes part of the access capacity. Copper is the second-lowest cost solution, but capacity needs are limiting the distance to meters or tens of meters. mmW E-band radio needs line of sight (LoS) and a quite stable installation, but capacity reaches 10 Gbps. In the future, D-band (140 GHz) radios will be beam-steerable, enabling easy alignment, tolerating installations on swaying light poles and easily supporting 25 Gbps and more, but only with limited distances like below a couple of hundred meters. The highest capacities are reached with optical cabling, but often the digging or leasing costs are limiting usage. MEC (Mul