QSFP28 is the main form factor for 100G optical modules. It features low power consumption, high port density, compact size, and cost efficiency. This article reviews QSFP28 module types and key WDM technologies like CWDM and DWDM. It also covers major modulation formats ( such as NRZ, PAM4, and. If you're upgrading leaf–spine fabrics, stitching campus buildings, or extending metro/edge links, a reliable Optical Transceiver Module at 100 Gbps is table stakes. This guide breaks down NS-branded QSFP28 modules—SR4, LR4, and DR—with practical advice on reach, fiber types, connectors, power. In 100G optical communication networks, QSFP28 (Quad Small Form-Factor Pluggable 28) is the mainstream packaging standard.