Category Archives: 100G Transceiver

What’s Difference Between CFP and CXP Transceivers?

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Two years ago, though everyone is talking about the 100G Ethernet as the next generation, it had still faced a lot of problems to be solved, seeming to be a long way off. But, technologies are developed very rapidly, and now 100G Ethernet is becoming more and more closer to us. Fiber connectivity in higher-speed active equipment is being condensed and simplified with plug-and-play, hot-swap transceiver miniaturization. Thus, optical transceiver technology is one of the basic but important technology to achieve the realiable and effective 100G Ethernet. Interfaces for 100G active equipment include CFP and CXP. So, what are CFP and CXP? And what’s the difference between CFP and CXP? Is CXP transceiver designed to replace the CFP? … You might be interested in them and have a lot of questions in your mind. Today, you will find the answer in this post.

About CFP
cfp-100g85-1m-ju-01CFP, short for C form-factor pluggable, is a multi-source agreement to produce a common form-factor for the transmission of high-speed digital signals. The c stands for the Latin letter C used to express the number 100 (centum), since the standard was primarily developed for 100 Gigabit Ethernet systems. In fact, CFP also supports the 40GbE. When talking about CFP, we always define it as multipurpose CFP, compared to the CXP which is discussed later.

The CFP MSA was formally launched at OFC/NFOEC 2009 in March by founding members Finisar, Opnext, and Sumitomo/ExceLight. The CFP form factor, as detailed in the MSA, supports both single-mode and multi-mode fiber and a variety of data rates, protocols, and link lengths, including all the physical media-dependent (PMD) interfaces encompassed in the IEEE 802.3ba standard. At 40GE, target optical interfaces include the 40GBase-SR4 for 100 meters (m) and the 40GBase-LR4 for 10 kilometers (km). There are three PMDs for 100 GE: 100GBase-SR10 for 100 m, 100GBase-LR4 for 10 km, and 100GBase-ER4 for 40 km.

CFP was designed after the Small Form-factor Pluggable transceiver (SFP) interface, but is significantly larger to support 100Gbps. The electrical connection of a CFP uses 10 x 10Gbps lanes in each direction (RX, TX). The optical connection can support both 10 x 10Gbps and 4 x 25Gbps variants. CFP transceivers can support a single 100Gbps signal like 100GE or OTU4 or one or more 40Gbps signals like 40GE, OTU3, or STM-256/OC-768.

The CFP-MSA Committee has defined three form factors:

  • CFP – Currently at standard revision 1.4 and is widely available in the market
  • CFP2 – Currently at draft revision 0.3 is half the size of the CFP transceiver; these are recently available in the market
  • CFP4 – Standard is not yet available, is half the size of a CFP2 transceiver, not yet available

CFP transceiver today to future

The original CFP specification was proposed at a time when 10Gbps signals were far more achievable than 25Gbps signals. As such to achieve 100Gbps line rate, the most affordable solution was based on 10 lanes of 10Gbps. However as expected, improvements in technology has allowed higher performance and higher density. Hence the development of the CFP2 and CFP4 specifications. While electrical similar, they specify a form-factor of 1/2 and 1/4 respectively in size of the original specification. Note that CFP, CFP2 and CFP4 modules are not interchangable (but would be interoperable at the optical interface with approriate connectors).

About CXP
CXPCXP is targeted at the clustering and high-speed computing markets, so we usually called it high-density CXP. Technically, the CFP will work with multimode fiber for short-reach applications, but it is not really optimized in size for the multimode fiber market, most notably because the multimode fiber market requires high faceplate density. The CXP was created to satisfy the high-density requirements of the data center, targeting parallel interconnections for 12x QDR InfiniBand (120 Gbps), 100 GbE, and proprietary links between systems collocated in the same facility. The InfiniBand Trade Association is currently standardizing the CXP.

The CXP is 45 mm in length and 27 mm in width, making it slightly larger than an XFP. It includes 12 transmit and 12 receive channels in its compact package. This is achieved via a connector configuration similar to that of the CFP. For perspective, the CXP enables a front panel density that is greater than that of an SFP+ running at 10 Gbps.

Typical applications of CXP in the data center include 100GE over Copper (CXP): 7m (23ft) and 100GE over multimode fiber: CXP for short reach applications (CFP is used for longer reach applications).

What’s the Difference Between CFP and CXP?
Despite having a similar acronym and emerging at roughly the same time, the CFP and CXP form factors are markedly different in terms of size, density, and intended application. The CFP and CXP optical transceiver form factors are hot pluggable, both feature transmit and receive functions, and both support data rates of 40 and 100 Gbps. But the similarities begin and end there. Aimed primarily at 40- and 100-Gigabit Ethernet (GbE) applications, the CFP supports both singlemode and multimode fiber and can accommodate a host of data rates, protocols, and link lengths. The CXP, by contrast, is targeted at the clustering and high-speed computing markets. The two are therefore complementary, not competitive, according to several sources. Thus, the existence of CXP does not mean the replacing of CFP.

However, things are never black and white. In some case, there is a competition between CFP and CXP, as CFP can also be used with multimode fiber. It becomes more of a choice for system vendors. Do they need to build a box that can adapt to any interface? If so, they would probably use CFP. If it’s a box that is just focused on the short-reach market, then they would probably use something more like CXP.

I hope this post will let you more understanding the 100GbE transceivers, whether CFP or CXP. Similarly, you could kown the 40GbE transceiver through this post as the CFP and CXP also support the 40GbE. If you want to have a further study on this subject, I suggest you to learn the related refference of MSA.

Article Source: http://www.fiber-optic-transceiver-module.com/whats-difference-between-cfp-and-cxp-transceivers.html

The Chanllenges of Technology And Cost 100G Faced

More and more high bandwidth services such as high definition(HD) video, online games and video conference challenging the traditional network, 100G as a ease network bandwidth technology, becomes the new hope of the operator.

100G industry chain has matured, with all components and subsystems have commercial capacity of multiple manufacturers, the market also needs the support of 100G system, the backbone network will be fully transferred to the 100G-leading era. From the early 2013, the focus point of 100G is from the laboratory into 100G network deployment and the commercial 100G has started.

Four Technical Challenges Of 100G

Although the 100G has been carried out, but the 100G transmission technology meets four technical challenges.

First, high power consumption. The achievement mechanism of 100G technology is complex, the optical receiver requires the use of coherent reception and processing of the DSP, the key chip has no ASIC, resulting in high power consumption of the whole 100G system. When large-scale commercial 100G technology, the average power consumption of each wavelength is still a problem waiting to be solved. Currently the power consumption of per wavelength is above 200W, the average power consumption of per frame is 7000W, so there will need three frames. Obviously, the 28nm process can help to reduce energy consumption, but there is no 100G solution of 28-nanometer. In addition, although the light energy consumption is not large, but due to the use of next-generation optical transceiver will increase greatly, reducing the power consumption is very necessary.

The second is integrated, especially in the field of optical circuit and photoelectric integration. How to add mass active and passive optical devices such as laser, optical amplifier, wavelength division multiplexing(WDM) and transmitter/receiver to the network to achieve highly integrated? Using semiconductor technology to the integration of CWDM and laser?

The third is test. The challenges of 100G testing include the quality evaluation of the deployed 100G system signal and the system maintenance after deployed. 100G using polarization multiplexing, and the signal spectrum is wide, the common OSDR and test instruments can not real-time test it, only by shutting off the laser method. How to achieve real-time test is industry’s future research topic, many of today’s online testing system are worth studying.

The Fourth is few prospective studies. How to make the current transmission system gradually shift to user-oriented management from the traditional network management? Quickly and efficiently allocate the physical resources?

The key is the problem of cost

The key reason why 100G failed to be applied large-scale currently is the opportunity cost is relatively too high. In the era of 100G, the cost of optical module is very high. The mainstream CFP module, the actual sales price is more than $10,000. From the point of optical module cost, 100G module is several times higher than 10G optical module. It also requires manufacturers continue to make efforts in chip integration, integrated optical module miniaturization and system design, to achieve the overall cost of products are reduced.

Especially the regard of optical module technology, the cost of this part is the key of the whole 100G system cost, the optical module itself has to face the challenges of control power consumption and improve board integration.

The 100G Industry Chain Still Needs To Improve

With the outbreak of emerging businesses such as high-definition video, social games, cloud computing and Internet of things, explosive growth of Internet content, so that the needs of next generation of Ethernet is increasing. Although the 40G/100G standards have been promulgated, the demand is also constantly stimulated, operators also verified the 100G with a commercial ability, but its scale popularity seems to have a distance, especially for 100G. What is the reason hindering the popularization, in technically what need to improve? When can really go the way of 100G?

The too high cost hinders 100G popularity And market maturity needs 3 years

China Telecom Technology Committee Director Wei Leping said, to achieve the scale of promotion, the cost of 100G applications should be controlled at as 5-6 times as the cost of 10G, there is a certain distance currently. Ruijie experts said, from the point of the cost of fiber optic transceiver, 100G module costs several times higher than the cost of 10G transceiver. It also requires the upstream and downstream of the industrial chain complement each other, continue working hard in chip integration, integration of optical module miniaturization and system design, to achieve cost reduction of the overall product. In addition, the architecture design of network manufacturers are also important factors, the role of the scale cost reduction such as supporting cables, wiring and tools also can not be ignored.

Overall, the 40G and 100G markets are in the early stage of market, but in contrast, the growth rate of 40G is faster than 100G, for example, Ruijie has made a considerable number of 40G commercial cases.

While the 100G standard has completed, but there are still not small challenges in the core of the optical module/high-speed signal processing technology, 100G commercial products also just launched by manufacturers. Therefore, experts believe that, the mature of 100G market is expected to take at least three years.

As we all know, the optical module technology cost is the key of the whole 100G system cost. But the 100G optical module devices are mainly controlled by foreign companies, although there are some Chinese enterprises introduced the 100G optical modules, but the quantity is too small, which virtually increases the 100G system cost.

There are still defects in technical and need to further improve the industrial chain

The 100G industrial chain including chip, optical devices, router to optical transmission system, and even the deployment, but the current situation is that, in the fiber optic module, the high-end core technology are basically controlled by foreign countries. Many experts said, the Chinese module makers have not domestic semiconductor chip production technology,  no continuous wavelength tunable lasers and high-end modulator chip, the manufacturer can do 100G optical devices is rare. Although there are more and more manufacturers to join this camp now, but many companies just re-processing of imported products, the lack of core technology, so there is no competition.

In addition to the short supply and not enough maturity of chip, optical devices and so on, some experts pointed out, the 100G industry chain supporting needs to be further improved, not only because the 100G optical network construction was just started, but also because the development of the 100G still faces challenges from the technology and market, for example, still exist cognitive gap in the line, construction, adjusting and testing, industry chain parties need to work together.

40/100G complement each other

Demand determines the market. From the current applications, in addition to some large data centers, the vast majority applications do not need the 100G bandwidth now, the bandwidth of 40G is sufficient; while the 40G products are more cost-effective than 100G products, and is expected to last a period of time, so the 40G products develop more smoothly than 100G in the moment. But apparently, the scene requires higher performance is relatively urgent demand for 100G, typical scenes such as super computing, cluster computing, etc. In the future, 40G and 100G will complement each other, service users in different application scenarios.