QSFP28 (Quad Small Form-factor Pluggable 28) and SFP28 (Small Form-factor Pluggable 28) are both types of optical transceivers used in high-speed data communication applications. The main difference between the two lies in their size and data transfer capabilities.

1. Size: - QSFP28 modules are larger in size, with a form factor that can accommodate up to 4 channels of high-speed data transmission. They typically have 38 pins for electrical connectivity. - SFP28 modules are smaller in size, with a form factor that can accommodate a single channel of high-speed data transmission. They typically have 20 pins for electrical connectivity.

2. Data Transfer Capability: - QSFP28 modules are capable of transferring data at speeds of up to 100 Gbps per channel, enabling a total data transfer capacity of 400 Gbps for a 4-channel module. - SFP28 modules are capable of transferring data at speeds of up to 25 Gbps per channel.

In summary, QSFP28 modules are larger and designed for higher-speed data transmission, while SFP28 modules are smaller and designed for lower-speed data transmission.

How it Works

Working hand in hand, QSFP28 to SFP28 breakout connectivity demonstrate how both cables complement one another in 100G networks. Breakout cables, known as DACs and AOCs, are a great solution for upgrading your network without the added complexity of fiber cabling. Breakout DAC and AOCs consist of a 100G QSFP28 end, split to four 25G SFP28 ends to aggregate 25G traffic to a 100G port.

Is SFP28 compatible with QSFP28?

SFP+ is mainly linked to 10G, while SFP28 is commonly associated with 25G connections. They use the same form factor, and the pinouts of SFP28 and SFP+ connectors are mating compatible. So SFP28 will work with SFP+ optics but at a reduced speed of 10 Gbit/s. 10G SFP+ modules will work well with the SFP28 port on a network switch if the port can be set up for 10G transmission, otherwise, the SFP+ modules can not work.