transceivers for qsfp28 to sfp28 in 2021

Many people are searching for solutions that will enable them to interface qsfp28 to sfp28. One popular method you can use to achieve this goal is to use a qsfp28 to sfp28 adapter. You could also use a qsfp28 breakout cable from QSFPTEK. The qsfp28 to sfp28 adapter can enable you to migrate to 100 gigabit ethernet.

The big question on peoples’ minds is, “isn’t it better to buy a breakout or fanout cable?” What more benefits will a qsfp28 to sfp28 adapter give me? We will answer those questions and more shortly.

Qsfp28 to Sfp28 Adapter – Is It The Magic Bullet?

QSFP28 Adapter
QSFP28 Adapter

The adapter is a qsfp28 module that has a receptacle for connecting sfp28 connectors at the back. The adapter acts as a middleman between qsfp28 and sfp28 cables. You can connect an sfp28 module to this adapter and connect the adapter to a qsfp28 port to enable the transition between the two speeds.

This adapter is the best way to convert a qsfp28 port to accept sfp28 cables. Also, the adapter has an EEPROM id that enables you to connect the adapter to switches of various companies.

Unlike the operating temperature of common optical transceivers, the Qsa28 adapter can work in high-temperature servers. The operating temperature of this module is between -10 degrees and 85 degrees centigrade. This is a much wider temperature range than optical transceivers support.

Another benefit of the qsfp28 to sfp28 adapter is that it does not cause extra latency. It is because of the lack of signal processing that this adapter doesn’t add any delay in the signal.

The adapter can work in many ports including Qsfp28, qsfp dd, qsfp+, and qsfp56. You can also connect it to many types of cables including the SR sfp multimode cable, sfp multimode AOC cable, the lr sfp single-mode cable, and the base-t sfp converter.

Why Not Use A Breakout Cable Instead Of The Qsfp28 to Sfp28 Adapter?

The qsfp28 to sfp+ breakout cable is a cable with a qsfp28 connector on one end that splits into four sfp+ connectors on the opposite end. The breakout cable uses duplex serial connections to enable two-way communication on all four sfp+ ports. The breakout cable is a short-distance connector best suited for use within the same rack.

So, why not skip the qsfp28 to sfp28 adapter and use a breakout cable instead. Let us compare the two alternatives to determine the one best suited for the job. The key areas we will look at include performance, cost, and compatibility.

Qsfp28 to Sfp28 Adapter Cost

The qsfp28 to sfp28 adapter does not conform to the Multi-source Agreement (MSA). Only one company owns patent rights to this adapter. Because of this monopoly, the company charges other vendors a lot of money for the rights to produce the adapter. A qsfp28 breakout cable complies with the MSA standard. That means several manufacturers have permission to make the cable. The cable works with devices from other companies so long as they meet MSA standards.

The takeaway here is that the qsfp28 to sfp28 adapter is a lot more expensive than the qsfp28 breakout cable from QSFPTEK.

100G to 25G break out cable
100G to 25G break out cable

Qsfp28 to Sfp28 Adapter Performance

The adapter gives you the flexibility to connect any sfp28 connector to a 100Gb sfp port. The issue people have with the QSA28 adapter is that it currently supports 25G-100G speed. It means that when you use this adapter, you will downgrade the connection from 100 Gbps to 25 Gbps. You will not harness the extra 75 Gbps bandwidth when you use the qsfp28 to sfp28 adapter.

The breakout cable does not have this limitation. You can split a 100 Gbps connection into four 25 Gbps cables that work at full speed.

Qsfp28 To Sfp28 Adapter Compatibility

Because of the lack of MSA standard support, using a qsfp28 to sfp28 adapter will be hit and miss. It is because manufacturers of devices like switches and routers do not have to support the adapter. Some manufacturers break support with generic optical modules.

Power Consumption Of Qsfp28 to Sfp28 Adapter

The QSA28 adapter is a passive device. It receives the signal from the sfp28 module and passes it to the qsfp28 port. Since the adapter does not process the signal, it does not consume any power. A breakout cable consumes power to work.

Things To Keep In Mind About The Adapters and Breakout Cable

  • To ensure the connection between the qsfp28 port and sfp28 connector works, you must enable fanout mode on the host device. You should also know that not all devices support fanout mode, so consult the manual.
  • You can connect an sfp28 module to a qsfp28 port using the adapter. But, you cannot connect a qsfp28 module into an sfp28 port.
  • The communication industry is quickly changing. Sometimes it will be cheaper to buy high-speed equipment to be able to keep up with the changing market rather than resorting to intermediary measures.
  • The technology behind qsfp28 to sfp28 breakout cables has advanced rapidly. Thus, the breakout cables are guaranteed to work on any host device. Even if a host device manufacturer uses vendor lock-in, a compatible breakout cable from QSFPTEK will work on the device.


If you are migrating from a 100g port to 25g connections, you can use either the breakout cable or adapter. However, after considering the performance of the cables, compatibility across host devices, and cost, there is only one winner. The breakout cable comes out on top regardless of the challenge.

You can use the qsfp28 to sfp28 adapter as an intermediate step before installing breakout cables. There is a big probability that you will need to recover the unused capacity that is created when using an adapter. QSFPTEK has a very high-quality qsfp28 to sfp28 breakout cable that works with many host devices. It is also very affordable compared to other brands. The quality of their cables is second to none. To get your hands on the best value breakout cable send an email to