25G SFP28 AOC: The Market and Trends

In general, there are three ways of 25G access of server, namely DAC (Direct Attach Cable), optical transceiver and AOC(Active Optical Cable).

DAC can reach no more than 5m, so it is difficult to meet the requirements of cross-rack wiring distance.

The optical transceiver can reach up to 100m or more using multi-mode fiber, but the cost is high.

AOC is an Active Optical Cable. AOC can reach up to 30m at a reasonable cost.

Therefore, AOC cable is a good choice for cross-rack server access, which is more suitable for China’s current data center rack power and network architecture. Here’s some information about the 25G AOC that you may be wondering about.

25G AOC provides a cost-effective solution for those same data center applications that require longer distance interconnect using active optical Ethernet technology. There are some advantages to 25G AOC.

The Advantages of 25G AOC

25G is the next trend from 10G to reduce the cost per Gbit/sec

25G provides 2.5 times the bandwidth of 10G using in the same SFP form factor

25G is ideal for data center top of the rack, wireless backhaul and enterprise interconnect applications

25G meets the newest server adapter requirements

10/25G transceivers are compatible with 10G, 25G, 40G and 100G transceivers

The Gigalight 25G SFP28 Active Optical Cables (AOCs) are direct-attach fiber assemblies with SFP28 connectors, compliant with 25G Ethernet IEEE 802.3by 25GBASE-SR standard. They are suitable for short distances and offer a cost-effective solution to connect within racks and across adjacent racks. The length is up to 70 meters using OM3 MMF and 100 meters using OM4 MMF. COB solution is used in the TX and RX.

The Highlights and Advantages of Gigalight 25G SFP28 AOC

Low power consumption<1W

The pre-FEC bit error ratio (BER) is guaranteed to meet E10-8 25.78125Gb/s@PRBS31, 55℃, Better than the IEEE pre-FEC BER of less than 5 E-5.

Mature COB technology

Low Cost

High capacity, timely delivery

CE, UL, RoHS, GR-468 test report

Active Optical Cables Market by Protocol Type

Ethernet

InfiniBand

HDMI PCI Express (PCIe)

Thunderbolt

Others

Application of AOC

Active Optical Cable assembly. Cable assemblies that use fiber–optic transceivers and fiber-optic interconnect to transmit high-speed serial data such as InfiniBand and Ethernet.

Data center

The data center is expected to lead the end-user segment of the active optical cable in recent years.

Active optical cables play a key role in the data center market. Active optical cables are largely used in the data center to meet the need for increased bandwidth and low power. The data center market also needs a broad portfolio of fiber optic modules to connect servers, switches, and storage, which is accomplished by an active optical cable. Therefore, the increase in the deployment of data centers is a key factor behind the growth of the active optical cable market.

High-Performance Computing

Consumer Electronics

Telecommunication

Global Key Region Production Market Share

China

China will be the leading country in the active optical cable market in the APAC region in recent years.

North America

North America is expected to hold the largest market share in recent years. Currently, North America holds the largest share of the active optical cable market. The U.S. invests heavily in the data center sector which is becoming a major hub for the integration of active optical cable. Huge numbers of the data center are seen in the U.S., where active optical cables are increasingly being used.

Europe

APAC

APAC is estimated to grow at the highest rate in the overall market till 2022. The data center and consumer electronics are major sectors driving the growth of the active optical cable market in the APAC.

RoW

Conclusion

Within the data center, AOCs continue to be deployed to optimize the existing infrastructure by providing higher data rates among servers, switches and storage facilities. Since China’s data center AOC commercialization in 2013, Gigalight has successfully developed a series of rich and comprehensive product portfolios that meet the requirements of next-generation data centers. As one of the global AOC providers around the world, Gigalight has a complete product line includes SFP, QSFP, SFP-DD, CXP, QSFP-DD form factor. The latest product portfolios include the ultra-high-speed 400G QSFP-DD AOC, 200G QSFP-DD AOC, 200G QSFP56 AOC, and 100G QSFP28 AOC, etc.. Gigalight also provides data center customers with customized products and services to meet the more extreme requirements.

Which One Is the Option for 5G Fronthaul? 10G, 25G or 100G?

5G is expected to be implemented in the following years. To have this 5G network realized, optical communication will be the cornerstone technology independent of various fronthaul options. The demand for high-rate optical transceivers will significantly increase because higher base-station density is required for the 5G network.

Although it is still not clearly determined which fronthaul architecture will be used in the 5G network, it is apparent that the network would employ both grey and color optics for 25Gbps based on 5G bandwidth requirement.

Grey and Color Optics

The light in WDM systems is carried over different wavelengths compliant with specific standards.

To distinguish wavelengths in different systems, the wavelengths in WDM systems are called colored light whereas the wavelengths in common optical systems are called grey light.

Grey light is within a certain wavelength range and does not have a standard wavelength, for example, the light at client-side optical ports of WDM devices.

Colored light is WDM-side optical signals of the OTN or line boards in a WDM system. The signals can be directly transmitted to multiplexer devices and have standard wavelengths.

Colored light is divided into CWDM and DWDM light, depending on wavelength division standards.

For 5G network, Gigalight has a complete portfolio of 10Gbps and 25Gbps optical transceivers that are tailored for upcoming standards such as eCPRI/NGFI as well as traditional CPRI options.

Gigalight 25G SFP28 transceivers also play in a critical role in the growing bandwidth demand in next generation access networks such as 5G wireless. While interface developments, like the recently released eCPRI specifications, will help improve bandwidth efficiency, the 5G wireless infrastructure will require significantly higher capacity in the optical links. Compact, power and cost-efficient 25G transceivers supporting both Ethernet and CPRI-10 while exposed to the elements will play a key role in supporting the rollout of this next generation wireless infrastructure.

Conclusion

At present, 10G optical transceivers were mainly used in LTE base stations. In the 5G network, it is expected that 25G and even 100G optical transceivers shall be the preferred solutions of the optical fronthaul network.

5G Is Driving the Evolution of Optical Transceiver Industry

We are now starting to see commercial 5G networks going live. Previous generations were focused on consumer and personal communications but now 5G will serve consumers, enterprises and take the internet of things to the next level, where superior connectivity is a prerequisite. Initially, 5G will be a capacity enhancer in metropolitan areas and enhanced mobile broadband and fixed wireless access will be ways for operators to address explosive traffic growth.

According to LightCounting, 5G will drive significant growth in the global market for optical transceivers since 2019, especially in China. At the same time, the demand for low-speed optical devices below 10G will gradually decrease and increase in the demand for transceivers of 25G, 50G, and 100G.

The change of optical transceiver demand is driven by 5G revolution. RAN architecture of the 5G system will realize the separation of CU and DU, which determines that 5G wireless network will include fronthaul, midhaul and backhaul. New requirements are proposed in terms of the amount of optical transceiver and the technical requirements of the optical transceiver.

Optical transceivers Need to Be Able to Meet the Requirements for Bearer Network in 5G Era

Fronthaul

The transmission distance should be within 10km or even shorter. The operating temperature should reach industrial temperature and the CPRI interface rate should reach 25Gbps.

Midhaul

The transmission distance should be at least 10km and the operating temperature should reach the commercial temperature. Gray optical transceiver or BiDi is mainly considered. In addition, 50G PAM4 may be a good choice.

Backhaul

The transmission distance should be more than 10km and the operating temperature should reach the commercial temperature. The 100G, 200G, 400G rate optical transceiver is mainly used. In addition, WDM or coherence technology will be taken into consideration.

Since the evolution of CPRI interface to PRI will lead to an increase of RRU power consumption, more heat-resistant optical transceivers are needed. In addition, the wireless architecture will evolve from DRAN to CRAN, and there will be a shortage of optical cable resources, which requires more energy-saving optical transceivers. In addition, 5G will use a higher frequency band, the coverage will be smaller, and the number of optical transceivers will be greatly increased so that the low-cost optical transceivers are needed. At the same time, 5G’s spectrum bandwidth increases transmission bandwidth, and higher speed optical transceivers are needed to meet this demand.

Conclusion

All in all, the core requirements for optical devices in wireless scenarios are mainly reflected in higher operating temperature range, less fiber resource consumption, lower cost, and faster single wave rate.

How to meet these needs of optical transceivers in the 5G era?

The solutions for High-temperature transceiver — industrial temperature light chip and silicon light can make the optical device itself work at high temperature, and can guarantee rapid heat conduction through good thermal design.

The solutions for optical fiber resource shortage—the most obvious solution is to use BiDi, which can save 50% of the optical fiber resources and thus use the existing optical fiber resources to transmit twice the bandwidth. Passive WDM solutions are also available.

Building on the success of the company’s 10G CWDM SFP+

transceiver and 10G DWDM SFP+ transceiver, Gigalight developed its next-generation 25G CWDM in an SFP28 form factor. And Gigalight 25G SFP28 BiDi optical transceivers are available. This technology is believed to be a key building block for deploying these transceivers and is designed to enable cost-effective next-generation 5G wireless build-outs while also providing significantly more data capacity per fiber than other 25Gbased optical architectures. This will enable Transceiver-to-transceiver communications and self-wavelength tuning of remote transceivers during commissioning without host interaction, so field installation and remote maintenance are simplified and operational expenses are lowered.

According to different scenarios, there are different requirements for optical transceivers. The traditional optical device technology in the field can meet the current needs, but there is a trend to update the technical field of evolution. At the same time, the realization path of the growth of optical transceiver rate also presents a diversification trend. Finally, no matter what you need are, Gigalight is here to create, assist and innovate.

In Case You Missed the Questions for 25G Transceiver

Here’s a frequently asked question to address questions that have arisen from the significant uptick in the use of 25G transceivers, which is driven by high bandwidth demands in the enterprise, data center and service provider applications.

1. Why is the use of 25G increasing?

Many network operators have chosen 25G instead of multiple 10G’s because 25G provides 2.5x bandwidth of the 10G in the same familiar SFP form factor at approximately the same power. This has enabled network equipment manufacturers to provide higher bandwidth connectivity. Rack-mountable switches and routers populated with 12 ports, 24 ports, and 48 ports on a single 1 RU faceplate are common for SFP.

2. What is the cost per bit of 25G?

25G provides 2.5x the bandwidth of 10G at a slight increase in cost. The result is nearly a 50% reduction in the cost per bit.

3. Is 25G standardized?

The IEEE (Institute of Electrical and Electronic Engineers) has standardized 25G. See IEEE802.3by and IEEE802.3cc for the details.

4. Which popular Gigalight’s 25G transceivers are available today?

25G SFP28 SR 100mIndustrial

25G SFP28 LR 10km Industrial

25G SFP28 ER Lite 20km Industrial

25G LWDM SFP28 ER 40km Industrial

25G SFP28 BiDi 10km Industrial

25G SFP28 BiDi 20km Industrial

25G CWDM SFP28 10km Industrial

5. What is SFP28?

SFP28 is the standardized pluggable form factor for 25G transceivers. It has the same mechanical dimensions as 10G SFP+ and 1G SFP. The electrical interface of 25G was envisioned to operate up to 28Gbps to accommodate overhead for a 25Gbps signal. Today most 25G transceivers operate at a 25.78125Gbps nominal data rate. The standards body that defines SFP28 is SFF (Small Form Factor Committee).

6. What is SR?

SR is Short Reach, and generally refers to transceivers that operate over MMF up to a few 100 meters.

7. What is LR?

LR is Long Reach, and generally refers to transceivers that operate over SMF at up to 10km.

8. What is ER?

ER is Extended Reach, the data rate of the transceivers support distance up to 40km over single mode fiber and use 1550nm lasers.

9. What is BiDi?

BiDi is called bi-direction as well. BiDi transceiver usually consists of two different wavelengths to achieve transmission in both directions on just one fiber (single-mode or multi-mode). Unlike general optical transceivers which have two ports, BiDi transceivers have only one port.

10. What is CWDM?

CWDM is Coarse Wavelength Division Multiplexer, a process of combining multiple wavelengths into a single fiber optical cable. Considering the smooth evolution of 5G equipment and the development of the industry chain, 25G CWDM SFP28 solution can well solve the current 5G millimeter wave pre-transmission problem.

11. What does “10/25G” mean?

These are dual-rate transceivers that support both 10G and 25G rates.

12. What New Technology Is in 25G Transceivers?

25G transceivers have CDR (Clock Data Recovery) circuits and generally require FEC (Forward Error Correction).

13. Where can additional information about Gigaligh 25G transceivers be found?

See the Gigalight 25G: https://www.gigalight.com/5g-fronthaul-optical-transceivers.html