How 100G ER4 Enables Reliable Connectivity for 5G Core and Metro Aggregation Networks

As 5G networks continue to evolve, the demand for high-capacity, low-latency, and reliable optical links between network nodes has grown dramatically. The 5G core and metro aggregation layers must handle massive amounts of data generated by distributed base stations, edge nodes, and user devices. To support this transformation, the 100G ER4 optical module has emerged as a crucial technology for building robust and scalable network infrastructure that extends beyond traditional data centers into metro and carrier environments.

The Growing Need for High-Performance Optical Links in 5G

5G architecture introduces new challenges for network transport. Unlike previous generations, 5G relies on a distributed, service-based architecture where data flows between numerous components such as the Centralized Unit (CU), Distributed Unit (DU), and Core Network. This leads to a significant increase in east-west traffic and places higher demands on link capacity, reliability, and latency performance.

Traditional 10G or 25G solutions are no longer sufficient for such intensive traffic loads. Meanwhile, coherent transmission systems such as DWDM can be costly and complex for metro-scale deployments. The 100G ER4 module fills this gap by providing a cost-effective, power-efficient solution capable of reaching up to 40 kilometers over single-mode fiber (SMF) without requiring additional amplification or dispersion compensation equipment.

Technical Overview of 100G ER4

The 100G ER4 module is based on four CWDM lanes, each transmitting 25Gbps, to achieve a combined 100Gbps line rate. It uses DFB lasers operating in the 1295nm–1310nm wavelength range and PIN photodiodes for reception. The module conforms to the IEEE 802.3ba 100GBASE-ER4 standard and is typically packaged in a QSFP28 form factor.

Role in 5G Core and Metro Aggregation Networks

In 5G core networks, QSFP28 ER4 modules enable interconnection between distributed data centers and network functions located across metropolitan areas. They facilitate seamless communication between core routers, edge gateways, and virtualized network functions (VNFs) hosted in different locations. The module’s 40km reach ensures stable performance across metro and regional links, reducing the need for intermediate repeaters or optical amplifiers.

At the metro aggregation layer, where traffic from multiple 5G base stations converges, 100G ER4 provides high-bandwidth aggregation with minimal latency. Its use of standard single-mode fiber and QSFP28 interfaces simplifies network expansion and ensures compatibility with existing equipment. Compared to DWDM solutions, it offers a lower total cost of ownership (TCO) while maintaining the reliability required for carrier-grade applications.

Furthermore, 100G ER4 supports network slicing and low-latency backhaul, which are essential for emerging 5G applications such as autonomous driving, smart manufacturing, and augmented reality. The stable optical link ensures real-time data transport between edge nodes and the 5G core, guaranteeing service continuity and performance consistency.

Balancing Performance, Cost, and Scalability

From a deployment perspective, 100G ER4 offers an optimal balance between performance and cost. For network operators upgrading from 10G or 40G systems, ER4 enables a smooth migration path without overhauling the entire optical infrastructure. Its compatibility with standard single-mode cabling and 100G switches allows gradual scaling as bandwidth demand increases.

In addition, the module’s power efficiency contributes to reduced operational costs, which is particularly important for large-scale metro networks where hundreds of ports may be deployed. By minimizing energy consumption and maintenance complexity, 100G ER4 ensures long-term network sustainability.

Conclusion

The 100G ER4 module plays a vital role in bridging the performance gap between data centers, metro networks, and 5G core systems. With its 40km reach, low latency, and cost-efficient design, it enables carriers and service providers to deliver reliable, high-capacity connectivity that meets the demands of next-generation communication services. As 5G continues to expand, 100G ER4 remains an indispensable building block for constructing robust and future-ready transport networks.