Network Slicing in the Transmission Network: The Hidden Backbone of 5G

When we talk about network slicing in 5G, the spotlight is often on the RAN and Core. But without slicing in the transmission network (transport), end-to-end slicing cannot be guaranteed. The transmission network—spanning fronthaul, midhaul, and backhaul—must provide isolation, guaranteed bandwidth, and latency assurance for each slice.

What is Transmission Network Slicing?

Transmission slicing partitions the transport layer into multiple logical networks, each aligned with a 5G slice. It ensures that traffic from eMBB, uRLLC, or mMTC slices travels across the same physical fiber, switches, or routers without interfering with one another.

For example:

• eMBB slice: requires high throughput for video and data-heavy services.

• uRLLC slice: needs deterministic latency and ultra-reliability.

• mMTC slice: prioritizes scalability for millions of IoT devices.

Enablers of Transmission Slicing

1. SDN (Software-Defined Networking): Provides centralized, automated slice provisioning and traffic steering.

2. eFlex Ethernet Slicing: Supports flexible Ethernet-based traffic separation, enabling operators to dynamically assign bandwidth to slices.

3. HQoS (Hierarchical QoS): Ensures that within a slice, traffic can be prioritized further (e.g., video vs. signaling), guaranteeing fairness and SLA compliance.

4. QoS Policies: Differentiates traffic classes, mapping slice requirements into queue scheduling, latency budgets, and bandwidth guarantees.

5. Segment Routing (SR) & MPLS: Offer per-slice routing and traffic engineering capabilities across IP/MPLS networks.

6. DetNet (Deterministic Networking): Provides bounded latency for time-critical slices.

Benefits

• End-to-End SLA Assurance: Transmission slicing guarantees that service-level agreements set in the RAN and Core extend seamlessly across transport.

• Efficient Resource Use: Shared infrastructure is fully utilized without compromising isolation.

• Service Differentiation: Enterprises can order transport slices with unique performance guarantees.

• Dynamic Scaling: Bandwidth and latency allocations can adjust in real time.

Challenges

• Complex Orchestration: Coordinating across optical, Ethernet, and IP/MPLS layers is demanding.

• Latency Guarantees: Maintaining ultra-low latency across multi-vendor, multi-layer networks is complex.

• Security Isolation: Each slice must be fully separated to avoid leakage or interference.

Conclusion

Transmission network slicing, powered by technologies like eFlex Ethernet slicing, HQoS, and advanced QoS models, is the foundation of end-to-end slicing. By ensuring that transport is programmable, flexible, and SLA-driven, operators can unlock the full potential of 5G—whether for streaming 8K video, enabling autonomous driving, or powering Industry 4.0.