How Much Do You Know QSFP28?

In recent years, we have witnessed the prosperity of the telecom market. Many research company predicts that the market of 2017 for telecommunication field will continue to thrive. With such a bright future, fiber optics market attracts a wide attention and many vendors want a piece of pie. At present, 40G is ubiquitous in the data center and 100G is accelerating. 100 Gigabit Ethernet (100GbE) are groups of computer networking technologies for transmitting Ethernet frames at rates of 100 gigabits per second (100 Gbit/s) after 40 gigabits per second (40 Gbit/s). The technology was defined by 802.3bm-2015 standards.

As for the optical transceiver, it has been developed in the past decades to adapt to the high-speed requirement from 1G to 40G even to 100G. Believe it or not, 100G is coming. How about the 100G optical transceivers? There are many form factors of 100G transceivers including CXP, CFP, CFP2, CPAK, CFP4 and QSFP28. Among them, QSFP28 and CFP optical transceiver are the most commonly used 100G transceivers. In this text, we would mainly introduce one type — QSFP28.

Information About QSFP28

The QSFP28, also called “QSFP100” or “100QSFP”, is designed to carry 100 Gigabit Ethernet. This transceiver type is also used with direct-attach breakout cables to adapt a single 100GbE port to four independent 25 gigabit Ethernet ports (QSFP28-to-4x-SFP28). The interconnect offers four channels of high-speed differential signals with data rates ranging from 25 Gbps up to potentially 40 Gbps, and will meet 100 Gbps Ethernet (4×25 Gbps) and 100 Gbps 4X InfiniBand Enhanced Data Rate (EDR) requirements. The QSFP28 transceiver is a high-density, high speed product solution designed for applications in the communications, data center and networking markets. QSFP28 is fast becoming the universal data center form factor.

Types of QSFP28

In order to meet the demands of various applications, there are many types of QSFP28 transceivers, such as QSFP28–100GBASE-SR4, QSFP28–100GBASE-LR4, QSFP28–100GBASE-CWDM4, QSFP28–100GBASE-IR4, QSFP28–100GBASE-PSM4… QSFP28 transceiver is typically available in two standard — 100GBASE-SR4 and 100GBASE-LR4. QSFP28–100G-LR4 and QSFP28–100G-CWDM4 will be chiefly described in the following passage.


The letters “LR” here stand for “long range”, and QSFP28–100G-LR4 supports links of up to 10 km. The module size is 18.4 mm × 72 mm × 8.5 mm. It is a fully integrated 4 × 25Gbit/s optical transceiver module that consists of 1310nm wavelength lasers, Driver ICs, PIN photo-diodes, and clock and data recovery (CDR) ICs with 25 Gbit/s electrical interfaces for operation over a pair of single mode fiber with duplex LC connectors. Its mechanical dimensions, connectors, footprint of it conform to SFF-8661 specification. QSFP28–100G-LR4 is hot pluggable via a 38-pin connector. Designed for high port densities, the maximum power consumption of QSFP28–100G-LR4 is TBD and its power supply voltage is +3.3 V with its compact size and low power consumption. QSFP28–100G-LR4 is used in data centers, high performance computing networks, and service provider transport networks.


The 100G QSFP28 CWDM4 optical transceiver is a full duplex, photonic -integrated optic transceiver that provides a high-speed link at aggregated data rate of 103.13 Gbps over 2 km of single mode fiber with a maximum link budget of 8 dB when maximum transmitter and dispersion penalty (TDP) of 3 dB is presented. It is fully compliant with IEEE Std 802.3bj clause 91. This module features a hot-pluggable electrical interface, low power consumption and 2-wire 12C management interface.QSFP28–100G-CWDM4 is applicable to local area network, wide area network, Ethernet switches and routers applications. With high compatibility, it is compliant with many standards, such as 100G CWDM4 MSA Technical Specification Rev 1.0, IEEE 802.3bm CAUI-4 chip to module electrical standard, SFF-8661 Rev 2.3 QSFP28 Module Mechanical…


QSFP28 is designed for 100G Ethernet with high density and high compatibility. You can choose an appropriate one for yourself based on you own need. If you are in the absence of a transceiver for transmission data over long distance via single mode fiber, QSFP28–100G-LR4 will be great. When the distance is much shorter via single mode fiber, QSFP28–100G-CWDM4 is highly recommended.

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