In Time Sensitive Networking, which transport application should be configured for the highest priority?

In a mobile network architecture, the fronthaul segment connects the Radio Unit (RU) to the Distributed Unit (DU). This link carries extremely time-critical traffic, such as Common Public Radio Interface (CPRI) or evolved CPRI (eCPRI) data, which has stringent, sub-millisecond latency and jitter requirements. Time-Sensitive Networking (TSN) is employed to guarantee these deterministic transport characteristics. To meet these strict performance demands, fronthaul traffic must be assigned the highest priority to ensure it is processed and forwarded with minimal delay, ahead of all other traffic types like midhaul or backhaul.

B. Long haul: This is a general term for long-distance transport and not a specific segment within the 5G RAN architecture with the most stringent latency requirements.
C. Midhaul: This segment connects the Distributed Unit (DU) to the Centralized Unit (CU). While it has strict latency requirements, they are less stringent (typically in milliseconds) than those of the fronthaul.
D. Backhaul: This segment connects the Radio Access Network (RAN) to the core network. It has the most relaxed latency and jitter requirements compared to fronthaul and midhaul.

1. Nokia Official Documentation: In the Nokia white paper "Time-sensitive networking for 5G," it is stated, "The 5G fronthaul network has very strict requirements for synchronization, latency and jitter... TSN provides the required mechanisms to guarantee the required QoS for fronthaul traffic." This highlights the critical nature of fronthaul that necessitates the highest priority. (Nokia, "Time-sensitive networking for 5G," White Paper, 2020, Page 4, Section: "TSN for 5G").

2. Peer-reviewed Academic Publications: A study on 5G transport networks states that latency requirements for fronthaul are typically under 250 µs, while midhaul is in the range of 5-10 ms, and backhaul is >10 ms. This clear hierarchy of latency budgets dictates that fronthaul traffic requires the highest forwarding priority. (Cavdar, C., & Gavrilovska, L. (2020). "5G Transport Network Slicing: A Survey." IEEE Communications Surveys & Tutorials, 22(3), 1939-1978. See Section III.A, "5G RAN Architecture and Transport Requirements"). DOI: https://doi.org/10.1109/COMST.2020.2998399

3. Standards Documentation (ITU-T): The International Telecommunication Union (ITU) Recommendation ITU-T G.8312, "Interfaces for a fronthaul network," defines the characteristics and stringent performance objectives for fronthaul networks, which are significantly tighter than those for other network segments, justifying the need for highest priority traffic handling. (ITU-T Recommendation G.8312, "Interfaces for a fronthaul network," Section 6, "Network performance objectives").