A QSFP (Quad Small Form-factor Pluggable) module is a compact, interchangeable plug-in module designed for high-performance network connections. Unlike traditional SFP modules, QSFP technology utilises four parallel data channels to enable high data transfer rates over fibre-optic or copper connections. QSFP modules and their further developments are primarily used in data centres, corporate networks and for connecting high-performance switches and servers.
A QSFP module is inserted into a compatible port on a network device. In optical variants, electrical signals are converted into light signals and transmitted via fibre-optic cables. Copper-based versions, on the other hand, enable direct electrical data transmission.
The distinctive feature lies in the four data channels, through which information can be transmitted in parallel. Depending on the module and transmission standard, these channels can be used for a single high-speed connection or for several separate connections. QSFP modules are generally hot-swappable and can be replaced whilst the network device is switched on.
The QSFP family comprises various generations, which differ in terms of their supported bandwidth and technical specifications.
| Module type | Typical speed | Range of application |
|---|---|---|
| QSFP | Up to 4 Gbit/s | Older network and storage connections |
| QSFP+ | 40 Gbit/s | Switch uplinks, data centres |
| QSFP28 | 100 Gbit/s | High-performance server and network connections |
| QSFP-DD | 400 Gbit/s; newer versions offer even higher speeds | Modern high-speed networks |
Important: An identical or similar design does not guarantee full compatibility. Whether modules from different QSFP generations can be used depends on the supported port speeds and the specifications provided by the network equipment manufacturer.
SFP modules typically use a single data channel, whilst QSFP modules support four parallel channels. This enables the QSFP family to provide higher overall bandwidths per port.
Breakout involves splitting a high-speed port into several independent connections. For example, a suitable 40G QSFP+ port can provide four separate 10G connections. This requires the network device to support this operating mode.
