QSFP28 stands for Quad Small Form-Factor Pluggable 28. It is a compact, high-density, hot-pluggable transceiver module used in data communication and telecommunication applications. The "Quad" in QSFP refers to its four-channel design, meaning that it supports four separate data channels. The "SFP" stands for Small Form-Factor Pluggable, indicating that it is a type of optical transceiver module with a small and standardized form factor.

100G QSFP28

The "28" in QSFP28 specifically denotes that the transceiver is designed to support data rates of up to 28 gigabits per second (Gbps) per channel. Therefore, a QSFP28 module is capable of aggregating data across its four channels, resulting in a total data transfer rate of up to 100 Gbps (4 channels x 28 Gbps).

QSFP28 modules are commonly used in high-speed networking applications, such as 100 Gigabit Ethernet, and can also be used for InfiniBand and other high-performance computing interconnects. They come in various versions, supporting different types of optical connectors (such as SR4, LR4, and ER4) and different types of optical fibers (multimode or single-mode).

As technology has advanced, newer form factors like QSFP56 (supporting up to 56 Gbps per channel) have been developed to meet the growing demand for higher data rates, but QSFP28 remains widely used and relevant in many networking applications.