This guide breaks down NS-branded QSFP28 modules—SR4, LR4, and DR—with practical advice on reach, fiber types, connectors, power, DOM, interoperability, and lifecycle management. Now, we will introduce the QSFP28 100G LR4 optical transceiver module, covering its definition, working principle, specifications, applications, and FAQs. This defines how the switch ASIC talks to the module. The module converts these four electrical lanes into four optical. Designed for long-reach 100G links on 1310nm single-mode fiber (SMF), QSFP 100G LR4 has become a go-to choice for connecting switches, routers, and interconnect systems across buildings, campuses, and metro-edge facilities — while still keeping the deployment simple and standardized.