400GBASESR4

400GBASESR4 is a high-speed Ethernet standard designed for data center and enterprise networks. It operates at a data rate of 400 gigabits per second (Gbps) over multimode fiber optic cables, specifically optimized for short-range applications. The "SR" in the name stands for short range, indicating its intended use within data centers and campus networks where distances are relatively short, typically up to 100 meters.

The 400GBASESR4 standard utilizes four lanes of 100 gigabits per second (Gbps) each, leveraging the 400GBASE standard. This configuration allows for high bandwidth and low latency, making it suitable for applications that require rapid data transfer, such as high-performance computing, virtualization, and cloud services.

The physical layer of 400GBASESR4 employs 50/125 µm multimode fiber (MMF) with an 850 nm wavelength, which is cost-effective and widely available. The use of multimode fiber enables the standard to support shorter distances compared to single-mode fiber, making it an economical choice for many data center environments.

400GBASESR4 is part of the IEEE 802.3bs standard, which was finalized in 2017. It is designed to complement other high-speed Ethernet standards, such as 400GBASEDR4 and 400GBASEFR4, each optimized for different fiber types and distance requirements. The adoption of 400GBASESR4 helps to meet the growing demand for higher bandwidth in data centers, supporting the increasing volume of data generated by modern applications and services.