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What is the difference between QSFP and CFP4?
Knowledge Base + 2024.01.08

The QSFP (Quad Small Form-factor Pluggable) and CFP4 (C Form-Factor Pluggable 4) are both types of transceiver modules used in high-speed data communication applications, such as in data centers and telecommunications networks. However, there are several key differences between the two:

1.Size: QSFP modules are smaller in size compared to CFP4 modules. The QSFP module measures 18mm x 72mm, while the CFP4 module measures 26mm x 114mm.

2. Form factor: QSFP modules have a quad form factor, meaning they are designed to transmit and receive signals over four channels, while CFP4 modules are designed for transmitting and receiving signals over a single channel.

3. Transmission speed: QSFP modules are typically used for data rates of 40G and 100G, while CFP4 modules are used for data rates of 100G and 400G.

4. Power consumption: Because of their larger size and capacity, CFP4 modules generally have higher power consumption compared to QSFP modules.

5. Compatibility: QSFP and CFP4 modules are not interchangeable due to their different form factors and channel configurations. They are designed for specific applications and are not cross-compatible.

In summary, the main differences between QSFP and CFP4 modules are in their size, form factor, transmission speed, power consumption, and compatibility. Each type of module is designed for different applications and data transmission requirements.

The difference between 100G QSFP28 fiber optical transceiver and 100G CFP4 fiber optical transceiver

The 100G QSFP28 fiber optical transceiver is suitable for a variety of transmission distances and application scenarios, which is mainly used in 100G Ethernet and EDRInfiniBand, and is an important part of the 100G network. It has the advantages of low power consumption, small size, high port density, etc., and is liked by the majority of customers.

The 100G CFP fiber optical transceiver has gone through CFP, CFP2, and now CFP4 fiber optical transceiver. The technology is mature and can support hot swap. However, its volume is larger than that of QSFP28 fiber optical transceiver, with few categories, and it is not suitable for many application scenarios.

CFP4 is specified by CFP MSA, and its size is slightly larger than that of QSFP28. The interface between MAC and PHY varies according to the application, and control and monitoring are achieved through the MDIO interface. Generally it is used for access networks and metropolitan area networks.

100G QSFP28 is specified by IEEE. It is smaller in size than CFP4. It is currently one of the 100G modules with the highest level of integration (CXP is more integrated). The interface between MAC and PHY is CAUI-4, and control and monitoring are achieved through the I2C interface. Generally it is used in data centers.

CFP8 VS QSFP-DD: Which 400G Transceiver to Choose?

The upgrading path of the CFP series is CFP-CFP2-CFP4-CFP8, and QSFP-DD has also experienced hardware specifications from 1.0 to 4.0. These are all long-established form-factor series. Compared to the QSFP series, the CFP series seems to be less popular for obvious reasons — large size and high power consumption. Below we will detail the differences between CFP8 VS QSFP-DD.

How many form factors for 100G Optical Transceivers?

  • QSFP28: Taking the technology and squeezing down to the familiar QSFP form factor

  • CFP: The first 100G transceiver form factor, CFP’s are larger modules, and were based originally on 10 lanes of 10G

  • CFP2: The successor to the original CFP module, this boasts a higher port density and many transmisson options.

  • CFP4: Further improvements were made to the CFP module, including reductions in power consumtion as well as size.

How long the transceivers can reach?

StandardSupported DistanceFiber TypeConnector
100GBASE-ER440kmSMFDuplex LC
100GBASE-ER4Lite20 ~ 25kmSMFDuplex LC
100GBASE-LR410kmSMFDuplex LC
100GBASE-SR470m @ OM3
100m @ OM4
100GBASE-SR1070m @ OM3
150m @ OM4
100GBASE-CLR42kmSMFDuplex LC