h defines the synchronization requirements for fronthaul networks. This standard effectively takes the air-interface numbers from 3GPP and translates those into network and equipment limits for a fronthaul network serving such an air interface. It is from the IEEE 802.1CM limits that O-RAN derives its sync requirements. ITU-T-The standardization branch of ITU, which itself is an agency of the United Nations. ITU-T has been around for well over 100 years and traditionally has been responsible for defining the operation of telecom networks SO that multiple networks from many operators spread across the globe can move data between each other. The structure and terminology (they use "Recommendation" rather than "Standard" SO as to not be seen to try and tell any country what to do) are rather convoluted, but one small portion of it-a group referred to as Study Group 15, Question 13-is responsible for defining synchronization in telecom networks, which today means things like SyncE in networks that could be used for fronthaul applications. The O-RAN Alliance-As the name suggests, this pseudo-standards body (as in they are more needs-driven and do not necessarily have the oversight that the other bodies have) owns the O-RAN specification and all aspects of it, including synchronization. Unfortunately, the different focus areas and histories of the various standards bodies mean that they are not always in agreement. In particular, ITU-T often takes a more cautious, and hence less reactionary, approach to standardization, meaning that it frequently appears to be playing catch-up. An example of this is the characterization of FTS networks without SyncE- something that is awaiting further study by ITU-T, but that is already being required by multi- ple O-RAN operators. Because of these differences, occasionally discrepancies arise between standards. In general, when designing an O-RAN network, the requirements and allowances documented in the O-RAN standards themselves should be the over-arching driver. Further reading The