QSFP28 (Quad Small Form-Factor Pluggable 28) is a high-speed optical transceiver form factor designed for data communication applications. It is widely used in data centers, telecommunications, and networking equipment to provide high-bandwidth connectivity. Here's an overview of how QSFP28 works:

1. Form Factor:

• QSFP28 has a compact form factor that accommodates four channels of data transmission, with each channel operating at 25 Gbps (Gigabits per second).

• The "28" in QSFP28 denotes its capability to support data rates up to 28 Gbps per channel, with a total aggregate data rate of 100 Gbps (4 x 25 Gbps).

2. Optical and Electrical Interface:

• QSFP28 interfaces with the host equipment through a high-speed electrical interface. This interface supports communication with the host device, including the exchange of control signals and data.

• For optical connectivity, QSFP28 uses fiber optic cables to transmit and receive data. The type of fiber and the supported distances depend on the specific QSFP28 module and its intended application.

3. Optical Transceivers:

• QSFP28 modules house optical transceivers, which include components for converting electrical signals to optical signals (transmit) and optical signals back to electrical signals (receive).

• The transceivers include lasers or light-emitting diodes (LEDs) for transmitting optical signals and photodiodes for receiving optical signals.

4. Data Transmission:

• QSFP28 operates using four independent lanes, allowing it to transmit and receive data simultaneously on each channel.

• Each lane operates at a data rate of 25 Gbps, contributing to the overall data rate of 100 Gbps for the entire module.

5. MSA Standards:

• QSFP28 adheres to Multi-Source Agreement (MSA) standards, ensuring interoperability and compatibility with various networking equipment from different manufacturers.

• MSA standards define the mechanical, electrical, and optical characteristics of the QSFP28 form factor.

6. Application Scenarios:

• QSFP28 is used in various applications, including 100 Gigabit Ethernet (100GbE) connections in data centers, high-performance computing, telecommunications, and cloud computing environments.

7. Hot-Pluggable:

• QSFP28 modules are hot-pluggable, meaning they can be inserted or removed from a compatible port without disrupting the operation of the host device. This feature enhances flexibility and ease of maintenance.

In summary, QSFP28 works by leveraging a compact form factor, high-speed electrical interfaces, and fiber optic cables to transmit and receive data at a total data rate of 100 Gbps. Its design and standards compliance contribute to its widespread use in modern high-speed networking applications.