The speed of a QSFP (Quad Small Form-Factor Pluggable) connector is determined by the data rate or bandwidth supported by the QSFP module that is plugged into it. QSFP connectors are used for high-speed data communication in networking equipment, such as switches, routers, and network interface cards. 

The speed of a QSFP connector is closely tied to the generation of the QSFP module, and several generations exist:

1. QSFP (1st Generation):

• Supports data rates of up to 4 x 10 Gbps (40 Gbps) using four lanes.

2. QSFP+ (2nd Generation):

• Supports data rates of up to 4 x 25 Gbps (100 Gbps) using four lanes.

• Commonly used for 40 Gigabit Ethernet (40GbE) and 100 Gigabit Ethernet (100GbE) applications.

3. QSFP28 (3rd Generation):

• Supports data rates of up to 4 x 25 Gbps (100 Gbps) using four lanes.

• Also supports higher data rates of 4 x 50 Gbps (200 Gbps) and 8 x 25 Gbps (200 Gbps) configurations.

• Commonly used for 100GbE and 200GbE applications.

4. QSFP56 (4th Generation):

• Supports data rates of up to 4 x 50 Gbps (200 Gbps) using four lanes.

• Also supports higher data rates of 8 x 50 Gbps (400 Gbps) and 4 x 100 Gbps (400 Gbps) configurations.

• Designed for 200GbE and 400GbE applications.

The speed of a QSFP connector is determined by the data rate and the number of lanes supported by the specific QSFP module inserted into it. Higher-speed QSFP connectors are designed to accommodate the increasing demand for bandwidth in modern data centers and high-performance computing environments.

Always refer to the documentation and specifications provided by the QSFP module manufacturer or supplier to determine the exact data rate supported by a particular QSFP connector and module combination.