) the GTP. This GTP handling may be performed by a VNF hosted in a CSG, which then directs the user traffic to an appropriate server, or the entire functionality may be hosted in the CSG. Alternatively, a MEC platform (ETSI GS MEC 003) may be hosted in a CSG, or a vUPF implemented and afterwards (as part of the 5G core) 5G AFs may be similarly hosted [MEC 5G WP]. 6.6.6 Conclusions 5G presents multiple highly inter-related challenges to transport. Numerous technologies, both physical layer and higher layers, are being proposed to meet these challenges. Increased data rates mandate newer physical interfaces, and/or new techniques for bonding physical interfaces, but also impact network topology, forwarding paradigms, and placement of edge computing (MEC) platforms. Reduced latencies necessitate time-sensitive forwarding mechanisms and efficient SDN-based routing, and in some cases dictate MEC processing. Both high data rates and TSN impose the requirement for yet more highly accurate time and frequency synchronization. High reliability impacts system design and obligates deploying new resilience mechanisms. Data rate, latency, and reliability are all QoS criteria that may need to be monitored and traded off (e.g. via net- work slicing). Many of the new requirements and proposed mechanisms entail increased energy consumption, which needs to be countered by yet other means. And all the above mechanisms need to be deployed without introducing new security vulnerabilities. Non-standalone 4G/5G cases present yet further challenges to the transport segment; for example, integrated low PHY functionality for converged NEs. Network migration scenar- ios may be even more challenging as they typically attempt to leverage existing brownfield network infrastructure. References 1 Stein, Y.J., Geva, A., and Zigelboim, G. (November 2007). Delivering better time-of-day using synchronous Ethernet and 1588, ITSF-2007. 2 (2016). Feasibility study on new services and markets technology enablers for critical communications; Stage 1. Ava