The throughput of QSFP28 (Quad Small Form-factor Pluggable 28) is up to 100 Gbps (Gigabits per second) per port.

What are QSFP+ and QSFP28 transceivers?

QSFP+ is essentially the same transceiver form factor as QSFP. QSFP+ transceivers support a variety of communication standards including Ethernet, Fibre Channel and InfiniBand. As previously mentioned, the 4 channels of a QSFP+ optic can be combined into a single 40G connection. So, you can increase bandwidth and port density while saving costs on inventory.

On the other hand, QSFP28 is an upgraded version of QSFP+.They even have almost identical form factors which allows QSFP28 ports in network equipment to accept both 100G QSFP28 and 40G QSFP+ transceivers. However, the big difference between the two is that QSFP28 transceivers are designed for 100G applications. QSFP28 supports 4 channels, and it can transmit 25G per channel to get a combined 100G of throughput.

However, the QSFP28 interface is very flexible as it can achieve 100G in other ways. Using a breakout connection, QSFP28 transceivers can use just 2 channels at 50G each or they can even achieve a single channel of 100G depending on the transceiver type being used. 100G QSFP28 transceivers are available in several different standards including SR4, LR4, PSM4 and CWDM4.

You can also consider dual rate options such as 40G/100G QSFP28 SR4, which is interoperable with legacy 40G SR4s in the network. With these available standards, you can achieve 100G in many different applications from short reach to extended reach.

Comparison of SFP vs SFP+ vs SFP28 vs QSFP+ vs QSFP28 SFP vs SFP+

Same size with different speeds and compatibility. SFP+ is used in 10-Gigabit Ethernet applications while SFP is for 100BASE or 1000BASE applications. SFP complies with the standards of IEEE802.3 and SFF-8472 while SFP+ is based on SFF-8431. SFP+ ports can accept SFP optics but at a reduced speed of 1 Gbit/s. An SFP+ transceiver can not be plugged into an SFP port, otherwise, the product or port may be damaged. Normally, SFP+ is more expensive than SFP.

SFP+ vs SFP28

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.Learn more about SFP28 module here: 25G SFP28 Transceiver Module Overview.

SFP+ vs QSFP+

The primary difference between QSFP+ and SFP is the quad form. QSFP+ is an evolution of QSFP to support four 10 Gbit/s channels carrying 10-Gigabit Ethernet, 10G Fiber Channel, or InfiniBand, which allows for 4x 10G cables and stackable networking designs that achieve better throughput. QSFP+ can replace 4 standard SFP+ transceivers, resulting in greater port density and overall system cost savings over SFP+. Get details about QSFP here: What Is QSFP+ Module: QSFP+ Transceiver Wiki and Types.

SFP28 vs QSFP28

SFP28 and QSFP28 transceivers actually adopt different sizes and working principles. SFP28 supports only one channel with 25 Gbit/s, while QSFP28 supports 4 separate lanes, and each is 25 Gbit/s. Both of them can be used in 100G networks, but the SFP28 is applied in the form of QSFP28 to the SFP28 breakout solution. Read article 100G QSFP28 Optical Transceiver Comparison to gain more pieces of information.

More specifications of SFP vs SFP+ vs SFP28 vs QSFP+ vs QSFP28 are listed in the following Table 1.