, but at intermediate switches. In order not to completely overwhelm the network with duplicate packets, intermediate switches also perform an erasure operation, whereby after forwarding a given packet, additional copies are discarded and not forwarded. 6.6.4.4 Frequency and Time Synchronization Frequency and time synchronization requirements of the NG-RAN are critical in order to assure: Maximizing data rates on the air interface by minimizing guard frequencies/times in order to maximize spectral efficiency, and utilizing bandwidth-boosting technologies like Carrier Aggregation (CA) and MIMO/COMP. Optimizing user experience, including smooth handover (significant reduction in call drops when sync is good), and reduced experienced delay. Supporting user applications that rely on highly accurate timing, such as location-based services. While frequency and time (or phase) are definitely related, reference sources and dissemi- nation at the highest accuracies employ very different technologies. Frequency references employ physical phenomena (such as narrow spectral lines of certain elements) and fre- quency distribution over communications links needs to be accomplished by the physical layer. Once a frequency reference is agreed upon, a time reference identifies particular moments in the periodic output of the frequency reference, and time distribution consists of sending data labeling these instants, and compensating for the propagation latency, which at high accuracy requires hardware time stamping, physical layer symmetry, and on-path support. 6 Enabling Technologies As a concrete example, a primary (frequency) reference clock (PRC) according to ITU-T G811 is required to have long-term frequency accuracy of 1 x 10-11 which will lead to a drift of up to 864 ns/day or 26 us/month. For more demanding applications, an enhanced PRC (ePRC) according to ITU-T G.811.1 is constrained for frequency accuracy of 1 x 10-12, which implies one tenth of these time drifts, that is, 84.4 ns/day and 2.6 us/month. This level of accu