Tag Archives: optical transceiver

100G DWDM QSFP: The Enabler of 100G Long Distance Connectivity

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100G transmission within data centers has made possible by using standard optical transceivers such as CFP and QSFP28 transceiver modules. Though they offer perfect fits for transferring 100G traffic within the rack and the data center, it becomes a problem when 100G traffic needs to be transported over long distances, like connectivity between geographically dispersed data centers over long distance (say over 40 km). This is where 100G DWDM QSFP transceiver finds its role to play. DWDM technology is nothing new to us since DWDM SFP transceivers have adopted in volume to expand 10G network capacity. 100G DWDM QSFP is very similar to its predecessor in regard to functionality, but it is typically applied in 100G network over longer span.

100G transmission distance

Why 100G DWDM QSFP Becomes the New Fashion

Traditional DWDM solutions are designed for telecom carries that most companies cannot afford, which hinders it for being used in data centers. However, data centers are confronted with the ongoing demand for expanding network capacity over longer distances. Which drives the needs to replicate or transfer traffic between geographically separated data centers. In this case, either conventional DWDM solution or QSFP28 transceiver is sufficient. 100G DWDM QSFP transceiver thus becomes the technology of choice for 100g DWDM optical networking transport over long distances (up to 80 km).

100G DWDM QSFP: The Longer Reach, More Agile Solution

100G DWDM QSFP is based on an advanced modulation technique – PAM4. It takes the same form factor as 100G QSFP28 transceiver and can be used directly on switches with QSFP28 slots. The main advantages of DWDM QSFP PAM4 is the easiness to use regular electronics and optical components suitable for QSFP28 form factor. The power consumption is dramatically reduced and can be used for data center interconnect application. The drawbacks, however, is that DWDM QSFP PAM4 requires amplification and dispersion compensation system on the optical link for reach longer than 5km at 100Gbits.

100G DWDM QSFP PAM4

QSFP DWDM PAM4 provides a cost effective solution for metro Data Center Interconnect (DCI) for up to 80km reach at 100 Gigabit/s speed. The 100G DWDM QSFP leverages IEEE CAUI-4 4x25G electrical interface and is compatible with standard 100G QSFP28 ports. On the optical side, it combines two wavelengths into a duplex fiber with the center wavelength aligning with 100GHz grid. 100G DWDM QSFP PAM4 is available in 40 different channels on the 100GHz ITU-T grid to provide a maximum bandwidth of 4Tbps over a single pair of fiber.

100G DWDM QSFP: Application in Data Center Interconnect (DCI)

Interconnecting geographically dispersed data centers is critical to maintain application agility to meet various business needs, while data intensive applications are driving the rapid growth of cloud networks. 100G DWDM QSFP transceiver delivers up to 4Tbps of bandwidth for up to 80km reach between data centers. This can be achieved by using DWDM Mux/Demux, amplifier and dispersion compensator. The Mux/Demux combines the different wavelengths of light into a pair of fiber. EDFA are used to boosts the signal. And a dispersion compensator is needed for applications over 5km. And DWDM is providing for efficient use of the single fiber pair with up to 40 wavelength multiplexed.

100G DWDM QSFP PAME for 80 KM

Conclusion

The emerge of 100G DWDM QSFP PAM4 is a significant step forward in overcoming the difficulties of DWDM networking in data center equipment. ACG Research covering data center service providers indicated that 30-80 km optical reach is needed for about 30% of their data center interconnections, which predicts the prosperity of 100G DWDM QSFP transceiver.

Related Article: 100G PAM4 QSFP28 or Coherent CFP

How to Select Transceivers for White Box Switch?

White box switch, also known as open switch, has gained popularity in data centers. Because they provide high performance switching and enable users a broader choice in software and hardware purchase at the same time. However, it’s the openness of open switches that leads to other problems: is there any limitation on the use of optic modules for white box switch? How to choose an optical transceiver for open switches?

white box switches

Considerations When Selecting Transceiver for White Box Switch

As we know, open switches vendors usually sell network switches either as bare-metal devices or preloaded with any compatible operating system, as requested by the purchaser. And there are many hardware and software vendors on the market. In order to achieve the desired performance with white box switch, some users may purchase hardware and software from different vendors. For example, one network operator may buy a white box switch from Dell, FS or HPE, but he will get a network operating system from Cumulus Linux. There is no fault of this action, but it will bring another problem—which type of optical transceivers can be used for the switch?

optical transceiver

According to the situation of white box switch on the market, there are two considerations should be taken into account when choosing an optical transceiver for white box switch.

The first one is the operating system (OS) of the switch. It’s known to us that there are various OS vendors like Cumulus Linux, Pica8 and HPE. They develop their own OS for their white box switch to get more market shares. Some of these companies also have their own optical transceiver production line. And some of them do not preclude the use of any industry-standard transceiver, which provide a freely choice for users to source standard components directly from manufacturers or from a broad range of re-sellers. Therefore, the transceivers from the corresponding OS vendor can be used for their open switches.

Another one is the optical transceiver itself. Not all white box switch vendors can provide transceivers for their switches. And some brand OEMs add enhancements to their standardized optic modules, which increases more cost on optics. However, some open switch vendors look forward to seeing an open standard without vendor lock-in. Therefore, cost-effective compatible optical transceivers that follow MSA SFF specification is another choice for white box switch. Among these compatible optical modules, most generic optical transceivers on the market can be used for white box switch.

Optical Transceiver Solution for White Box Switch

White box switches have been the way for web-scale data center operators who are able to drive down the cost and drive up efficiency and flexibility of their IT infrastructure, especially in some big companies like Facebook, Google or Amazon. And there is a growing group of companies that also want the same level of efficiency web-scale operators have achieved. How to realize this? More white box switches are required without question.

White-box switch market is booming. Under this situation, providers like FS.COM supplies 10GbE switch, 25GbE switch, 40GbE switch and 100GbE network switches preloaded with FS OS or Cumulus OS for small and medium size networks or data centers. And all the generic optical transceivers in FS.COM are available for white box network switches.

Related Article: What White Box Switch Means to SDN Deployment 


How Do Optical Transceiver Vendors Differentiate Their Transceiver Design?

In order to get a bigger share of the market. Optical transceiver vendors are challenged in how to differentiate their optical transceiver design and give the products conform to common form factors. To understand the importance of transceiver differentiation, it is worth reviewing the purpose of multi-source agreement (MSA) transceiver form factors.

Common form factors arose so that optical equipment makers could avoid developing their own interfaces or being locked into a supplier’s proprietary design. Judged in those terms, MSAs have been a roaring success. Equipment makers can now buy optical intoptical transceiver designerfaces from several sources, all battling for the design win. MSAs have also triggered a near-decade of innovation, resulting in form factors from the 300-pin large form factor transponder MSA to the pluggable SFP+, less than a 60th its size.

But MSAs, with their dictated size and electrical interfaces, are earmarked for specific sectors. As such the protocols, line rates, and distances they support are largely predefined. Little scope, then, for differentiation. Yet vendors have developed ways to stand out. One approach is to be a founding member of an MSA. This gives the inner circle of vendors a time-to-market advantage in securing customers for emerging standards. The CFP MSA for 40- and 100-Gigabit Ethernet is one such example.

Some designs required specialist optical components that only a few vendors have, such as high-speed VCSELs used for the latest Fibre Channel interfaces. In turn, many vendors don’t have the resources—design teams and the deep pockets—needed to develop advanced technologies, such as those for 40- and 100-Gbps transponders, whether it is integrated optical devices or integrated circuits.

Being the first to integrate existing designs into smaller form factors is another way to differentiate oneself. An example is JDSU, which has integrated a tunable laser into the pluggable XFP MSA. Fiberstore also then launched tunable XFP which features with tunable and multi-protocol functions in order to further expand the product lineup of the 10G optical transceiver modules.

Optical transceiver vendors are also differentiating their products through marketing approaches. New-entrant Far Eastern vendors are selling optical transceivers directly to service providers and data center operators, bypassing equipment makers. They are also looking to differentiate on price, cutting costs where they can (including R&D) and focusing on bread-and-butter designs. They are quite happy to leave the leading vendors to make the heavy investments and battle each other in the emerging 40- and 100-Gbps markets.

Some people think differentiation doesn’t matter so much for optical transceivers since even if a vendor gets a lead, others inevitable will follow. And anyway, the cost of transporting traffic is still too high evenoptical transceiver market with the fierce competition instigated by MSAs. In turn, optical transceivers are now a permanent industry fixture and they can’t be conjured to disappear.

For optical transceiver vendors, however, the result is a market that is brutal. So can optical transceiver vendors differentiate their products? Of course they can. FS.COM (Fiberstore), a company devoting on the research & development, and offering fiber connectivity network solutions for carriers, ISPs, content providers and networks, is the global market innovator and application technology pioneer in the field of optical network devices and interconnection. In the future, they seem to change this market.

Can We Interconnect SFP, SFP+, XFP, X2 and XENPAK?

There are many kinds of 10G optical transceivers in the market such as SFP+, XFP, X2 and XENPAK. So when we use these modules, the most confusing problem is if we can interconnect SFP+, XFP, X2 and XENPAK. Besides this, some module users also want to know if they can connect SFP to SFP+ or if then can connect 10GBASE-SR modules to 10GBASE-LR modules. In this article, I will display some common questions often asked by module users and give the right answer mainly based on Cisco optical transceivers.

1. Can we interconnect SFP-10G-SR to XENPAK-10GB-SR or X2-10GB-SR?
The answer is yes. For this problem, you just need the correct optic on each side. If your optics are singlemode you need singlemode patch cord. If your optics are multi-mode then you need multi-mode patch cord. SFP-10G-SR, XENPAK-10GB-SR and X2-10GB-SR are all multi-mode optics, so a multi-mode fiber can solve this problem.

2. Can LC-SC patch cord connect X2-10GB-SR between SFP-10G-SR?
Yes, it’ll work fine as long as your fiber patch cord is multi-mode. Actually, the SFP+ requires LC connector but the X2 may require a SC connector. So when connect SFP-10G-SR to X2-10GB-SR, we must use a LC-SC patch cable (LC connector on one fiber end, SC connector on the other fiber end).

connect X2-10GB-SR between SFP-10G-SR

3. Is it possible to connect X2-10GB-LR to SFP-10G-SR?
The answer is not possible. The Cisco X2-10GB-LR module supports a link length of 10 kilometers on standard single-mode fiber (SMF, G.652). However, the Cisco SFP-10G-SR module supports a link length of 300m on OM3 multi-mode fiber (MMF,OM3) and 400m on OM4 multi-mode fiber (MMF,OM4). Actually, you need to use modules with the same wavelengths, i. e. SR to SR or LR to LR.

4. Can we connect SFP-10G-SR to GLC-SX-MM?
The SFP-10G-SR is 10 Gbps only. The GLC-SX-MM is 1 Gbps only. This question means can we force SFP-10G-SR to use 1Gbps speed?  This is a very common question and the response will always be the same. The answer is NO. Because the SFP-10G-SR is 10 Gbps only. It runs at 10 Gbps link rate and no other speed. GBIC, SFP, X2, QSFP, CFP modules will only negotiate to one speed and one speed only. You cannot interconnect them.

SFP-10G-SR to GLC-SX-MM

5. Can we connect GLC-SX-MM to GLC-LH-SM?
Some users wonder if they can use GLC-SX-MM together with GLC-LH-SM? In fact, the GLC-SX-MM is multi-mode LED-based. The GLC-LH-SM is singlemode laser-based. They may (sometimes) work with mode conditioning patch (MCP) cables but it’s not generally a good idea unless it’s completely unavoidable.

Fiberstore (FS.COM) offers a variety of fiber optic transceivers (SFP+, XFP, X2 and XENPAK) at very economical prices which can satisfy your requirements from 1G to 100G Ethernet. In addition, all these optical transceivers are in stock and you can enjoy the same day shipping service. For more information, please contact us over sales@fs.com.

Related Article: Cisco SFP-10G-SR: All You Need to Know

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.