Comparison of QSFP28 and CFP Optics：Cost, Power Consumption, Port Density

Before the advent of 100G QSFP28 optical transceiver, 100G network is developed in the trend of 10G-40G-100G. However, with the appearance of 100G-Base QSFP28, the development mode tends to be 10G-25G-100G/10G-25G-50G-100G, and begins to prevail in the industry. Simultaneously, some data centers adopting this mode to achieve the upgrade from 10G to 100G.

In the development process of 100G optical transceivers, their  form factor type and standard are developed according to the cost and power consumption, which are regarded as the main drive in the development of interconnect market. QSFP28 is just conformed to these requirements. While compared with CFP similarly belonging to one of 100G optical modules, what is the difference between QSFP28 and CFP？ This article will make a comparison between QSFP28 and CFP series Optics.

What Is QSFP28 Optical Transceiver?
For QSFP28 optical module, except that it’s a hot-pluggable optical module designed for 100G data rate, it integrates 4 transmitting and 4 receiving channels. And “28” means each lane carries up to 28G data rate. Meanwhile it can do 4x25G/2x50G/1x100G connection.

In addition, the QSFP28 transceiver and interconnect cable are a high-density, high-speed product solution designed for applications in the telecommunications, data center and networking markets. The interconnect offers four channels of high-speed differential signals with data rates ranging from 25Gbps up to potentially 40Gbps, and will meet 100Gbps Ethernet (4x25Gbps) and 100Gbps 4X InfiniBand Enhanced Data Rate (EDR) requirements. QSFP28 is fast becoming the universal data center form factor. QSFP28 transceiver is typically available in two standards—100GBASE-SR4 and 100G QSFP28 LR4. 100G QSFP28 SR4 operates at multimode fiber for a distance of 100 m. 100GBASE-LR4 QSFP28 can support a much longer distance of 10 km.

What Is CFP Optical Transceiver?
CFP transceiver is designed after SFP transceiver interface, but it supports much larger internet speed, which is realized by using 10×10Gbit/s in each direction. The C stands for the Latin letter C, meaning the number 100 (centum). The 100G optical interconnect typically means 100GBASE-SR10 in 100 meter MMF, 100GBASE-LR10 and 100GBASE-LR4 in 10km SMF reach, and 100GBASE-ER10 and 100GBASE-ER4 in 40km SMF reach respectively. CFP transceiver is currently defined into two next-generation 100G form factors — CFP2 and CFP4. Compared with the existing CFP, CFP2 and CFP4 will be respectively double and quadruple front panel port density.





CFP Optical Module vs. QSFP28 Optical Transceiver: What Is the Difference？
For their differences, this article will  have an introduction to them in these aspects of cost, power consumption, port density.

Cost: now the data center is mainly 10G network architecture, its interconnect solutions are mainly 10GBASE-SR transceiver and duplex LC multimode patch cord. It will save a lot of time and cost if directly upgrade to 40G/100G network on the basis of the existing 10G network architecture.
Power Consumption: QSFP28 transceiver’s power consumption is usually less than 3.5W, while other 100G transceivers are usually between 6W and 24W. Therefore, QSFP28 transceiver’s power consumption is much lower than others.
Port density: The first generation 100G transceiver is CFP transceiver, having large volume, then is CFP2 and CFP4. CFP4 is the latest generation of 100G transceiver, its width is only 1/4 of CFP transceiver. While QSFP28 transceiver’s package is smaller than CFP4, this means QSFP28 transceiver has a higher port density on the switch.

Summary
Generally speaking, by comparison, QSFP28 optical transceiver is lower in consumption and cost, higher in port density. It bring new solutions for 100G applications to promote the fast development of 100G. The surge of QSFP28 shipments will be one of the factors to change the market from 40G to 100G, according to HIS.