QSFP (Quad Small Form-Factor Pluggable) transceivers come in various classifications, each designed for specific applications and use cases. The main classifications include:

1. QSFP SR4 (Short Range 4 lanes):

• Application: Short-range connections within a data center.

• Wavelength: Typically uses four parallel optics channels around 850nm.

• Data Rate: Supports data rates up to 40 Gbps per channel, providing a total of 160 Gbps.

2. QSFP LR4 (Long Range 4 lanes):

• Application: Longer-range connections, often used in metropolitan and enterprise networks.

• Wavelength: Utilizes four channels around 1310nm.

• Data Rate: Supports data rates up to 40 Gbps per channel, providing a total of 160 Gbps.

3. QSFP ER4 (Extended Range 4 lanes):

• Application: Extended-range connections in metro and regional networks.

• Wavelength: Uses four channels around 1310nm.

• Data Rate: Supports data rates up to 40 Gbps per channel, providing a total of 160 Gbps.

4. QSFP PSM4 (Parallel Single-Mode 4 lanes):

• Application: Short- to medium-distance connections within data centers.

• Wavelength: Employs parallel single-mode fibers for each of the four channels.

• Data Rate: Supports data rates up to 40 Gbps per channel, providing a total of 160 Gbps.

5. QSFP CWDM4 (Coarse Wavelength Division Multiplexing 4 lanes):

• Application: Uses CWDM technology for increased capacity.

• Wavelength: Utilizes four channels in the CWDM grid.

• Data Rate: Supports data rates up to 40 Gbps per channel, providing a total of 160 Gbps.

6. QSFP+ SR4 (Short Range 4 lanes):

• Application: Similar to QSFP SR4 but designed for 40GbE applications.

7. QSFP28:

• Application: Designed for 100 Gigabit Ethernet (100GbE) applications.

• Wavelength: Dependent on the specific variant (e.g., SR4, LR4, ER4).

• Data Rate: Supports data rates up to 25 Gbps per channel, providing a total of 100 Gbps.

8. QSFP-DD (Double Density):

• Application: Designed for higher data rates, including 200GbE and 400GbE.

• Wavelength: Dependent on the specific variant.

• Data Rate: Supports data rates beyond 25 Gbps per channel, with a total capacity of 200 Gbps or 400 Gbps.

These classifications represent various QSFP form factors designed to meet different distance and speed requirements in networking and telecommunications applications. The choice of QSFP transceiver depends on the specific needs of the network, such as the required data rate, reach, and application.