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QSFP28 vs CFP4 Optical Transceiver Form Factors

The QSFP28 and CFP4 are two of many form factors for 100G optical transceivers, which convert electrical data signals coming from data switches into optical signals that can be transmitted through optical fiber.

The QSFP28 and CFP4 have been cited as the two most popular form factors in the 100G optical transceiver market, thanks to a low power consumption, and due to having smaller dimensions compared with other form factors. By looking closely at QSFP28 vs CFP4 specifications, the differences between the two become more apparent, but it’s important to get an overview of the two form factors before diving into a direct comparison.


CFP4 Form Factor Overview

The CFP4 optical transceiver is a newer generation of the multi-source agreement (MSA) that outlined the original CFP form factor, which was established in 2009. It was the first 100G optical transceiver form factor to hit the market. There also is a CFP2, which came before the CFP4. Optics that fall under the CFP4 form factor can be used for both 40G and 100G Ethernet.


QSFP28 Form Factor Overview

Just like the CFP4 form factor, the QSFP28 optical transceiver is an improvement over its previous models, the QSFP and QSFP+, which were designed for 1G Ethernet and 10G Ethernet, respectfully. QSFP28 optics, unlike CFP4 optics, can be used only for 100G Ethernet.


Advantages and Disadvantages of QSFP28 vs CFP4

Both the QSFP28 and the CFP4 represent the third generation of their line of form factors, but as each has evolved, several key differences have developed.

Likely the biggest distinguishing factor of QSFP28 vs CFP4 is the fact that QSFP28 optics work only with 100G applications, whereas CFP4 optics work for both 100G and 40G applications. That being said, 100G Ethernet is becoming more common, especially for larger companies and organizations that require more bandwidth. But upgrading to 100G is much more expensive, so if you’re operating on 40G or less without any strain on your network, it may not be the best move to upgrade to 100G unless you’re expecting to experience significant growth very quickly.

When looking at QSFP28 vs CFP4, it’s also important to note how each form factor’s channels function. Optical transceivers that fall under CFP4 specifications support a 10-channel setup divided into 10G signals in addition to a 4-channel setup divided into 25G signals. QSFP28, on the other hand, only supports a 4-channel setup, but each lane is capable of carrying up to 28G Ethernet. This makes the CFP4 form factor more versatile in terms of channel setups, since it is capable of more configurations.

Another aspect of CFP4 that differentiates it from QSFP28 is that is has a higher maximum power consumption compared with QSFP28, which could be a plus if you need to transmit data over longer distances. But, if you’re looking to send data over shorter distances, the lower maximum power consumption on QSFP28 optics may be more efficient than CFP4.

Although the CFP4 is nearly half the size of its predecessor, CFP2, the dimensions of QSFP28 vs CFP4 are in favor of QSFP28 optics. The QSFP28 is only slightly smaller, but when you’re looking to use something like this in large quantities – such as in high-density data centers – every bit of space counts.


Brightstar Systems Resells High-Quality QSFP28 Optical Transceivers

We are an independent vendor for used QSFP28 optical transceivers, and many of our QSFP28 parts, such as the 100GBASE-SR4, the 100GBASE-LR4 and the 100GBASE-CWDM4, comply with existing MSAs. Upgrading networking hardware can be very costly, and purchasing our used QSFP28 optics will help reduce unnecessary expenditures for you, your company or your organization.