The maximum speed of a QSFP+ (Quad Small Form-Factor Pluggable Plus) transceiver depends on the specific configuration and the data rate per lane supported by that module. QSFP+ modules are designed to provide high-speed data transmission in data center and networking applications.

Here are some common QSFP+ variants and their associated maximum speeds:

1. QSFP+ (4x10G):

• Data Rate per Lane: 10 gigabits per second (Gbps)

• Maximum Speed: 4 lanes x 10 Gbps = 40 Gbps

2. QSFP+ (4x25G):

• Data Rate per Lane: 25 gigabits per second (Gbps)

• Maximum Speed: 4 lanes x 25 Gbps = 100 Gbps

3. QSFP28 (4x25G):

• Data Rate per Lane: 25 gigabits per second (Gbps)

• Maximum Speed: 4 lanes x 25 Gbps = 100 Gbps

4. QSFP56 (4x50G):

• Data Rate per Lane: 50 gigabits per second (Gbps)

• Maximum Speed: 4 lanes x 50 Gbps = 200 Gbps

5. QSFP-DD (8x25G):

• Data Rate per Lane: 25 gigabits per second (Gbps)

• Maximum Speed: 8 lanes x 25 Gbps = 200 Gbps

The maximum speed is determined by the total data rate across all the lanes in the QSFP+ module. Different configurations offer varying levels of maximum speed to meet the demands of different networking scenarios.

When selecting QSFP+ modules, it's important to consider the specific data rates required for the intended application, as well as the compatibility with networking equipment. Always refer to the module's datasheet or specifications for accurate information on supported data rates and maximum speed.