QSFP28 is the workhorse 100 G form factor: compact, hot-pluggable, and designed for four electrical lanes. It's defined by SFF-8665 (mechanical/electrical) and managed via SFF-8636 (DOM/DDM over I²C). Cisco ® QSFP28 100G ZR extends 100GbE coherent links from QSFP28 ports reaching up to 80km over dark fiber and up to 300km over amplified Dense Wave Division Multiplexing (DWDM) links. The 100G QSFP28 module solution provides high-performance 100GbE connectivity for data centres, enterprise core & distribution layers, computing networks and service provider applications. By providing four lanes of 25G, QSFP28 enables a streamlined upgrade path from lower-speed networks, making it a popular choice for scaling data center interconnect (DCI) and.