40G QSFP+ Applications and Developing Trends

40G QSFP+ Applications and Developing Trends

In recent years, in order to cope with the rapid development of high-definition video, cloud storage, and cloud computing; major IT giants and telecom operators are actively preparing and building large-scale data centers. The traditional 10G Ethernet obviously can not meet the requirements of data centers for high bandwidth. The proposal and application of the next-generation high-speed Ethernet are inevitable.

IEEE (Institute of Electrical and Electronics Engineers) has officially promulgated the 40G/100G Ethernet standard IEEE 802.3ba in June 2010, paving the way for the commercial use of 40G and 100G. Based on the consideration of cost and product maturity, 40G Ethernet technology has been widely used in data centers. The corresponding 40G optical transceiver module has also made good achievements in the booming field of the data center and still has great prospects in the foreseeable future. Firstly, this paper analyzes the application situation and trend of 40G QSFP+ optical transceivers in data centers; and then introduces the development trend of 40G optical transceivers.

Application Situation of 40G QSFP Transceivers

Facing the huge traffic pressure of the data center, giants such as Google, Microsoft; and Facebook are actively upgrading the existing data center. The current investment boom of data centers provides an opportunity for the development and growth of the whole optical transceiver module industry. According to the data analyzed by IHS Infonetics, in 2014, the sales of 10G, 40G; and 100G optical transceivers for enterprises and data center market increased by 21%; reaching the US $1.4 billion, accounting for 65% of the whole telecom and data communication market.

It is estimated that in the next few years, the main driving force for the overall growth of optical transceiver sales is the deployment and application of its data center. The 40G QSFP+ optical transceiver module is the main driver of its surge in demand. Compared with the second half of 2013, the sales of 40G optical transceivers in the second half of 2014 increased by 81%. Therefore, the 40G optical transceiver has a huge market and prospect in the data center market.

There are two main reasons why 40G QSFP+ optical transceivers are widely used in data centers. The first reason is that the demand for bandwidth within the data center is becoming higher and higher. In 2013, about 2.4 zettabytes of data center traffic were in the data center; accounting for 77% of the total data center traffic. By 2018, the internal data center traffic is estimated to reach 6.4 zettabytes. These flows mainly come from data exchange activities between storage and virtual machines.

Traditional 10G Ethernet :

Traditional 10G Ethernet can no longer be competent in data center server and storage applications. In order to solve this problem, IEEE has issued a new Ethernet standard IEEE 802.3ba in June 2010. This standard defines two Ethernet rates: 40G and 100G, which mainly meet the different needs of server and network applications. Among them, 40GE applied to server and computing applications, and 100GE applied to tandem and core network applications. 40G Ethernet technology and 40G optical transceiver modules; such as 40G QSFP+ SR4 and 40G QSFP+ LR4, are more suitable for large-scale deployment in the data center in terms of product maturity and cost. At the same time, because the 40G optical transceiver adopts the QSFP package; the interface size is the same as that of XFP module; which is more suitable for high-density deployment in the data center.

Another important reason is that the price of 100G Ethernet technology is too high. Although 100G can provide ten times the speed of 10G Ethernet, at present; only a few companies master the technology of optical devices in 100G optical transceiver and 100G PHY chip in MAC layer; so it is expensive and cannot be deployed on a large scale. In view of the above factors, the research on 40G QSFP+ optical transceivers has great practical significance from the perspective of the market. In addition, with the maturity of 40G technology; the selection of devices and chip schemes of 40G optical transceivers is gradually enriched. This will undoubtedly help to reduce the difficulty and cost of R&D. Finally, the study of 40G QSFP+ optical transceivers can also accumulate rich experience for the subsequent research and development of 100 G-related optical transceivers.

After development in recent years, the 40G optical transceiver is more mature in both technology and the market. From only a few companies, such as Finisar and JDSU; to now, enterprises in various countries have set foot in the 40G optical transceiver market. The main driving force is still huge market demand.

At present, 40G optical transceiver modules are mainly QSFP+ SR4 and QSFP+ LR4. 40G QSFP+ SR4 uses a 4-way 10Gbps multimode 850nm optical transceiver with an effective transmission distance of 100m. It is commonly used for data exchange in the data center. 40G QSFP+ LR4 uses 10Gbps 4-channel single-mode light in the bands of 1271nm; 1291nm, 1311nm and 1331nm, with an effective transmission distance of 10km. It can be used not only in the data center, but also in the communication between data centers. But in the long run, 40G should be regarded as an excessive product from 10G to 100G.

40G QSFP+ Applications

QSFPTEK Cisco Compatible 40GBASE-SR4 Transceiver

With the maturity of 100G devices and module schemes; the era of large-scale application of 100G optical transceivers will also come. At present, there are two main development routes of the 100G optical transceiver. The first is the CFP MSA standard formulated by Finisar, Opnext, and Sumitomo. Its package size evolves from the initial CFP to CFP2 to the latest CFP4 standard. The size of each generation is about half smaller than that of the previous generation.

The module width is from 82mm of CFP to 41.5mm of CFP2, and finally; 100G is controlled to 21.5mm under the CFP4 standard. This will make CFP4 have four times the board density of the first generation CFP; and its single transmission rate reaches 1.6tb/s. Another development route of 100G is the development of CXP standard (27mm wide, working in short-range multimode); developed by Infiniband industry alliance to QSFP28 with the same interface size as QSFP; and will be able to support 100GBASE-SR4 and 100GBASE-LR4 standards.

In addition, Cisco has independently developed its own 100G optical transceiver scheme CPAK, in which its own CMOS photonics technology is used to produce optical devices. The scheme adopts the highly integrated electrical design of the device, directly prints the whole circuit board on the silicon chip, creates a precedent for the optical transceiver to realize innovation and efficiency by using CMOS technology and makes Moore’s law applicable to the field of optical.


It can be seen from the above introduction that higher transmission rate; smaller packages and relatively lower cost are always the development trend of the optical transceiver industry at present and in the future. QSFPTEK is an original brand of fiber optic transceiver factory outlet that serves SMB users. It provides a full range of high-performance, low-power 40G QSFP+ series optical transceiver modules. Welcome to consult via sales@qsfptek.com.

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