Fiber Optic Components

Transceivers – Technological Information

As growing numbers of users begin to deploy more and more complex networking applications, the Internet traffic is mounting exponentially. Obvious is the need for bandwidth to enable high speed media download and upload, live video enjoyment, and cloud applications. To meet these demands, high port density transceivers used in network systems have gone through the evolution from CFP interface, to QSFP+ interface, and to CXP interface.

This article is about to tell some technological information about these three ports: CFP, QSFP, and CXP.


In 2007, the IEEE Higher Speed Study Group (HSSG) observed that core networking and computing applications were growing at different rates. Subsequently, this committee specified two rates in IEEE Std 802.3ba-2010: 40 Gigabit Ethernet and 100 Gigabit Ethernet (GbE). The IEEE Std 802.3ba-2010 (40/100GbE) standard encompasses a number of different Ethernet physical layer (PHY) specifications. A networking device or line card may support different PHY types by means of pluggable modules called transceivers.


It’s the Multi-Source Agreement (MSA) that standardizes the optical modules, and one agreement that supports 40 and 100GE is the C Form-factor Pluggable (CFP) MSA. The C stands for the Latin word for 100. This standard was primarily developed for 100GE to support distances more than 100 m.

CFP was designed after the Small Form-factor Pluggable transceiver (SFP) interface, but it is a significantly larger form factor to support 40Gbps and 100Gbps. The CFP form factor, as detailed in the MSA, supports both single-mode fiber (SMF) and multimode fiber (MMF) and a variety of data rates, protocols, and link lengths. The optical connection can support both 10 x 10Gbps and 4 x 25Gbps variants.


The Quad (4-channel) Small Form-factor Pluggable (often abbreviated as QSFP or QSFP+) is a compact, hot-pluggable transceiver used for data communications applications. It is an industry standard format defined by the Small Form Factor Committee (SFF-8436, Rev 3.4, Nov. 12, 2009—Specification for QSFP+ Copper and Optical Modules), supporting data rates from 4x10Gbps. QSFP modules increase the port density by 3x- 4x compared to SFP modules. Common applications include 40GE over copper QSFP+ with 7m (23ft) reach, as well as 40GE fiber QSFP+ with 100 meters reach over OM3 and 150 meters over OM4.

QSFP+ cable solutions mainly include QSFP+ direct-attached cable (DAC) using copper, as well as QSFP+ active optical cable (AOC) using fiber. Take Cisco QSFP-H40G-CU1M for example, Fiberstore compatible Cisco QSFP-H40G-CU1M runs over passive copper cable for cost-effective 40G links between QSFP ports of Cisco switches within racks and across adjacent racks. The figure below is the QSFP-H40G-CU1M product listed on Fiberstore.


CXP is about one in fourth the size of a CFP transceiver providing higher density network interfaces. Typical applications of CXP in the data center include 100GE over copper with 7m (23ft) reach and 100GE over MMF fiber for short reach.

There also exists hybrid transceivers that are widely used when devices without the same physical interface need to be connected. When these hybrid transceivers are combined with cable assembly, they can convert one form factor to another different form factor, like CFP to 4 SFP+, CFP to QSFP+, QSFP+ to 4 SFP+.


This transceiver technology information gives you clear insight of their respective features and applications, constituting a key point in the choice of transceivers in terms of port density, cost, and operating reach. As a leader in manufacturing and supplying fiber optical products, Fiberstore offers various kinds of transceivers (eg. CFP, QSFP, CXP) and cabling solutions, including QSFP+cable mentioned above. Please feel free to contact Fiberstore when you want to know more information about transceivers information.

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