SFP28 module - Definition

An SFP28 (Small Form-factor Pluggable 28) module is a compact, hot-swappable plug-in module for high-speed networks, which typically enables data transfer rates of 25 Gbit/s. It is inserted into compatible switches, routers or server network interface cards and, depending on the model, supports fibre-optic connections over various distances. SFP28 modules are used particularly in data centres, corporate networks and high-performance server environments where high bandwidths are required.

How does an SFP28 module work?

An SFP28 module is inserted into a compatible port on the network device. In the case of optical variants, it converts electrical signals into light signals, which are then transmitted via fibre-optic cables. Unlike multi-lane transceivers, SFP28 transmits data via a single high-speed data path. The modules are generally hot-swappable and can be replaced whilst the device is switched on. The connection in question is interrupted during this process.

SFP, SFP+ and SFP28: An overview of the differences

The module variants have a similar compact design but differ in terms of their typical transmission speeds.

Important: The same form factor does not automatically mean full compatibility. Many SFP28 ports also support 10 Gbit/s SFP+ modules. A 25G SFP28 module, on the other hand, will not automatically work in a dedicated 10G SFP+ port.

What SFP28 variants are available?

Depending on the distance and the existing cabling, various solutions are available:

• SFP28 SR (Short Range): For short multimode fibre-optic connections, typically up to 70 m with OM3 or 100 m with OM4.
• SFP28 LR (Long Range): For single-mode fibre-optic cables and distances typically up to 10 km.
• SFP28 DAC (Direct Attach Copper): Copper cables with permanently integrated connectors for short connections, for example within a server rack.
• SFP28 AOC (Active Optical Cable): Active optical cables with integrated connectors for connections where a separate fibre optic module is not required.

Are SFP28 modules compatible with SFP+ ports?

Not necessarily. An SFP28 module is designed for 25 Gbit/s and will only work in a 10G port if both the module and the network device explicitly support a compatible 10G operating mode.

When is SFP28 a better choice than SFP+?

Particularly when 10 Gbit/s is no longer sufficient for the required data transmission. SFP28 offers 2.5 times the nominal bandwidth of SFP+ and is suitable, for example, for heavily utilised server connections.