ost of other features, FlexE enables bonding of an arbitrary number of 25G links. Future developments will further increase data rates available for xHauling. The IEEE is currently working on enhancing the single-lane data rate to 50G (and hence the four-lane rate of 200 Gbps instead of 100G), and later to a full 100G (and hence a four-lane rate of 400 Gbps) (IEEE 802.3 cd, IEEE 802.3bs). 6.6.4.2 Achieving the Required Latencies The requirement for low latency for backhauling is ultimately derived from the E2E delay tolerated by the user application (unless this delay is unimportant, in which case the delay tolerated by control-plane signaling, for example RRC to PDCP configuration estimated at about 10 ms, dominates). For the general eMBB use case, this can usually be hundreds of milliseconds, while interactive voice or voice+video communications may suffer at more 6.6 Transport Network than tens of milliseconds. More demanding applications, such as gaming, AR/VR, and V2x, may require one-way E2E delays as low as 1 ms. Some factory automation applications demand delays from sensor to programmable logic controller as low as 0.25 ms (in addi- tion to extremely low PLRs); such low delays mandate local termination. Ultra-low delay will also be critical for recent innovations in manufacturing technologies, thought of as the fourth industrial revolution and thus called Industry 4.0, which introduce cyber-physical systems and cognitive computing. It should be noted that, from all these allowed E2E delays, one needs to deduct terminal processing times. Other important applications having strin- gent delay requirements, such as professional audio and video, are discussed in RFC 8578. Fronthaul and midhaul have additional, usually more stringent, latency requirements, deriving from operational and technological constraints rather than from the user applica- tion. For example, for midhaul with functional split options from 5 and below (defined in Section 4.1), HARQ response times put limitations on the transport. CPRI fron