Category Archives: data center

How Is 5G Pushing the 400G Network Transformation?

With the rapid technological disruption and the wholesale shift to digital, several organizations are now adopting 5G networks, thanks to the fast data transfer speeds and improved network reliability. The improved connectivity also means businesses can expand on their service delivery and even enhance user experiences, increasing market competitiveness and revenue generated.

Before we look at how 5G is driving the adoption of 400G transformation, let’s first understand what 5G and 400G are and how the two are related.

What is 5G?

5G is the latest wireless technology that delivers multi-Gbps peak data speeds and ultra-low latency. This technology marks a massive shift in communication with the potential to greatly transform how data is received and transferred. The increased reliability and a more consistent user experience also enable an array of new applications and use cases extending beyond network computing to include distributed computing.

And while the future of 5G is still being written, it’s already creating a wealth of opportunities for growth & innovation across industries. The fact that tech is constantly evolving and that no one knows exactly what will happen next is perhaps the fascinating aspect of 5G and its use cases. Whatever the future holds, one is likely certain: 5G will provide far more than just a speedier internet connection. It has the potential to disrupt businesses and change how customers engage and interact with products and services.

What is 400G?

400G or 400G Ethernet is the next generation of cloud infrastructure that offers a four-fold jump in max data-transfer speed from the standard maximum of 100G. This technology addresses the tremendous bandwidth demands on network infrastructure providers, partly due to the massive adoption of digital transformation initiatives.

Additionally, exponential data traffic growth driven by cloud storage, AI, and Machine Learning use cases has seen 400G become a key competitive advantage in the networking and communication world. Major data centers are also shifting to quicker, more scalable infrastructures to keep up with the ever-growing number of users, devices, and applications. Hence high-capacity connection is becoming quite critical.

How are 5G and 400G Related?

The 5G wireless technology, by default, offers greater speeds, reduced latencies, and increased data connection density. This makes it an attractive option for highly-demanding applications such as industrial IoT, smart cities, autonomous vehicles, VR, and AR. And while the 5G standard is theoretically powerful, its real-world use cases are only as good as the network architecture this wireless technology relies on.

The low-latency connections required between devices, data centers, and the cloud demands a reliable and scalable implementation of the edge-computing paradigms. This extends further to demand greater fiber densification at the edge and substantially higher data rates on the existing fiber networks. Luckily, 400G fills these networking gaps, allowing carriers, multiple-system operators (MSOs), and data center operators to streamline their operations to meet most of the 5G demands.

5G Use Cases Accelerating 400G transformation

As the demand for data-intensive services increases, organizations are beginning to see some business sense in investing in 5G and 400G technologies. Here are some of the major 5G applications driving 400G transformation.

High-Speed Video Streaming

The rapid adoption of 5G technology is expected to take the over-the-top viewing experience to a whole new level as demand for buffer-free video streaming, and high-quality content grows. Because video consumes the majority of mobile internet capacity today, the improved connectivity will give new opportunities for digital streaming companies. Video-on-demand (VOD) enthusiasts will also bid farewell to video buffering, thanks to the 5G network’s ultra-fast download speeds and super-low latency. Still, 400G Ethernet is required to ensure reliable power, efficiency, and density to support these applications.

Virtual Gaming

5G promises a more captivating future for gamers. The network’s speed enhances high-definition live streaming, and thanks to ultra-low latency, 5G gaming won’t be limited to high-end devices with a lot of processing power. In other words, high-graphics games can be displayed and controlled by a mobile device; however, processing, retrieval, and storage can all be done in the cloud.

Use cases such as low-latency Virtual Reality (VR) apps, which rely on fast feedback and near-real-time response times to give a more realistic experience, also benefit greatly from 5G. And as this wireless network becomes the standard, the quantity and sophistication of these applications are expected to peak. That is where 400G data centers and capabilities will play a critical role.

The Internet of Things (IoT)

Over the years, IoT has grown and become widely adopted across industries, from manufacturing and production to security and smart home deployments. Today, 5G and IoT are poised to allow applications that would have been unthinkable a few years ago. And while this ultra-fast wireless technology promises low latency and high network capacity to overcome the most significant barriers to IoT proliferation, the network infrastructure these applications rely on is a key determining factor. Taking 5G and IoT to the next level means solving the massive bandwidth demands while delivering high-end flexibility that gives devices near real-time ability to sense and respond.

400G Network

400G Ethernet as a Gateway to High-end Optical Networks

Continuous technological improvements and the increasing amount of data generated call for solid network infrastructures that support fast, reliable, and efficient data transfer and communication. Not long ago, 100G and 200G were considered sophisticated network upgrades, and things are getting even better.

Today, operators and service providers that were among the first to deploy 400G are already reaping big from their investments. Perhaps one of the most compelling features of 400G isn’t what it offers at the moment but rather its ability to accommodate further upgrades to 800G and beyond. What’s your take on 5G and 400G, or your progress in deploying these novel technologies?

Article Source: How Is 5G Pushing the 400G Network Transformation?

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How 400G Has Transformed Data Centers

With the rapid technological adoption witnessed in various industries across the world, data centers are adapting on the fly to keep up with the rising client expectations. History is also pointing to a data center evolution characterized by an ever-increasing change in fiber density, bandwidth, and lane speeds.

Data centers are shifting from 100G to 400G technologies in a bid to create more powerful networks that offer enhanced experiences to clients. Some of the factors pushing for 400G deployments include recent advancements in disruptive technologies such as AI, 5G, and cloud computing.

Today, forward-looking data centers that want to maximize cost while ensuring high-end compatibility and convenience have made 400G Ethernet a priority. Below, we have discussed the evolution of data centers, the popular 400G form factors, and what to expect in the data center switching market as technology continues to improve.

Evolution of Data Centers

The concept of data centers dates back to the 1940s, when the world’s first programmable computer, the Electronic Numerical Integrator and Computer, or ENIAC, was the apex of computational technology. The latter was primarily used by the US army to compute artillery fire during the Second World War. It was complex to maintain and operate and was only operated in a particular environment.

This saw the development of the first data centers centered on intelligence and secrecy. Ideally, a data center would have a single door and no windows. And besides the hundreds of feet of wiring and vacuum tubes, huge vents and fans were required for cooling. Refer to our data center evolution infographic to learn more about the rise of modern data centers and how technology has played a huge role in shaping the end-user center evolution

The Limits of Ordinary Data Centers

Some of the notable players driving the data center evolution are CPU design companies like Intel and AMD. The two have been advancing processor technologies, and both boost exceptional features that can support any workload.

And while most of these data center processors are reliable and optimized for several applications, they aren’t engineered for the specialized workloads that are coming up like big data analytics, machine learning, and artificial intelligence.

How 400G Has Transformed Data Centers

The move to 400 Gbps drastically transforms how data centers and data center interconnect (DCI) networks are engineered and built. This shift to 400G connections is more of a speculative and highly-dynamic game between the client and networking side.

Currently, two multisource agreements compete for the top spot as a form-factor of choice among consumers in the rapidly evolving 400G market. The two technologies are QSFP-DD and OSFP optical/pluggable transceivers.


QSFP-DD is the most preferred 400G optical form factor on the client-side, thanks to the various reach options available. The emergence of the Optical Internetworking Forum’s 400ZR and the trend toward combining switching and transmission in one box are the two factors driving the network side. Here, the choice of form factors narrows down to power and mechanics.

The OSFP being a bigger module, provides lots of useful space for DWDM components, plus it features heat dissipation capabilities up to 15W of power. When putting coherent capabilities into a small form factor, power is critical. This gives OSFP a competitive advantage on the network side.

And despite the OSFP’s power, space, and enhanced signal integrity performance, it’s not compatible with QSFP28 plugs. Additionally, its technology doesn’t have the 100Gbps version, so it cannot provide an efficient transition from legacy modules. This is another reason it has not been widely adopted on the client side.

However, the QSFP-DD is compatible with QSFP28 and QSFP plugs and has seen a lot of support in the market. The only challenge is its low power dissipation, often capped at 12 W. This makes it challenging to efficiently handle a coherent ASIC (application-specific integrated circuit) and keep it cool for an extended period.

The switch to 400GE data centers is also fueled by the server’s adoption of 25GE/50GE interfaces to meet the ever-growing demand for high-speed storage access and a vast amount of data processing.OSFP vs. QSFP-DD

The Future of 400G Data Center Switches

Cloud service provider companies such as Amazon, Facebook, and Microsoft are still deploying 100G to reduce costs. According to a report by Dell’Oro Group, 100G is expected to peak in the next two years. But despite 100G dominating the market now, 400G shipments are expected to surpass 15M million switch ports by 2023.

In 2018, the first batch of 400G switch systems based on 12.8 Tbps chips was released. Google, which then was the only cloud service provider, was among the earliest companies to get into the market. Fast-forward, other cloud service providers have entered the market helping fuel the transformation even further. Today, cloud service companies make a big chunk of 400G customers, but service providers are expected to be next in line.

Choosing a Data Center Switch

Data center switches are available in a range of form factors, designs, and switching capabilities. Depending on your unique use cases, you want to choose a reliable data center switch that provides high-end flexibility and is built for the environment in which they are deployed. Some of the critical factors to consider during the selection process are infrastructure scalability and ease of programmability. A good data center switch is power efficient with reliable cooling and should allow for easy customization and integration with automated tools and systems. Here is an article about Data Center Switch Wiki, Usage and Buying Tips.

Article Source: How 400G Has Transformed Data Centers

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Silicon Photonics: Next Revolution for 400G Data Center


With the explosion of 5G applications and cloud services, traditional technologies are facing fundamental limits of power consumption and transmission capacity, which drives the continual development of optical and silicon technology. Silicon photonics is an evolutionary technology enabling major improvements in density, performance and economics that is required to enable 400G data center applications and drives the next-generation optical communication networks. What is silicon photonics? How does it promote the revolution of 400G applications in data centers? Please keep reading the following contents to find out.

What Is Silicon Photonics Technology?

Silicon photonics (SiPh) is a material platform from which photonic integrated circuits (PICs) can be made. It uses silicon as the main fabrication element. PICs consume less power and generate less heat than conventional electronic circuits, offering the promise of energy-efficient bandwidth scaling.

It drives the miniaturization and integration of complex optical subsystems into silicon photonics chips, dramatically improving performance, footprint, and power efficiency.

Conventional Optics vs Silicon Photonics Optics

Here is a Technology Comparison Chart between Conventional Optics vs Silicon Photonics Optics, taking QSFPDD DR4 400G module and QDD DR4 400G Si for example:

The difference between a 400GBASE-DR4 QSFP-DD PAM4 optical transceiver module and a silicon photonic one just lies in: 400G silicon photonic chips — breaking the bottleneck of mega-scale data exchange, showing great advantages in low power consumption, small footprint, relatively low cost, easiness for large volume integration, etc.

Silicon photonic integrated circuits provide an ideal solution to realize the monolithic integration of photonic chips and electronic chips. Adopting silicon photonic design, a QDD-DR4-400G-Si module combines high-density & low-consumption, which largely reduces the cost of optical modules, thereby saving data center construction and operating expenses.

Why Adopt Silicon Photonics in Data Centers?

To Solve I/O Bottlenecks

The world’s growing data demand has caused bandwidths and computing power resources in data centers to be used up. Chips have to become faster when facing the growing demand for data consumption, which can process information faster than the signal can be transmitted in and out. That is to say, chips are becoming faster, but the optical signal (coming from the fiber) must still be converted to an electronic signal to communicate with the chip sitting on a board deep in the data center. And since the electrical signal still needs to travel some distance from the optical transceiver, where it was converted from light, to the processing and routing electronics — we’ve reached a point where the chip can process information faster than the electrical signal can get in and out of it.

To Reduce Power Consumption

Heating and power dissipation are enormous challenges for the computing industry. Power consumption will directly translate to heat. Power consumption causes heat, so what causes power dissipation? Mainly, data transmissions. It’s estimated that data centers have consumed 200TWh each year — more than the national energy consumption of some countries. Thus, some of the world’s largest Data Centers, including those of Amazon, Google, and Microsoft are located in Alaska and similar-climate countries due to the cold weather.

To Save Operation Budget

At present, a typical ultra-large data center has more than 100,000 servers and over 50,000 switches. The connection between them requires more than 1 million optical modules with around US$150 million-US$250 million, which accounts for 60% of the cost of the data center network, exceeding the sum of equipment such as switches, NICs, and cables. The high cost forces the industry to reduce the unit price of optical modules through technological upgrades. The introduction of fiber optic modules adopting Silicon Photonics technology is expected to solve this problem.

Silicon Photonics Applications in Communication

Silicon photonics has proven to be a compelling platform for enabling next-generation coherent optical communications and intra-data center interconnects. This technology can support a wide range of applications, from short-reach interconnects to long-haul communications, making a great contribution to next-generation networks.

  • 100G/400G Datacom: data centers and campus applications (to 10km)
  • Telecom: metro and long-haul applications (to 100 and 400 km)
  • Ultra short-reach optical interconnects and switches within routers, computers, HPC
  • Functional passive optical elements including AWGs, optical filters, couplers, and splitters
  • 400G transceiver products including embedded 400G optical modules400G DAC Breakout cables, transmitters/receivers, active optical cables (AOCs), as well as 400G DACs.

Now & Future of Silicon Photonics

Yole predicted that the silicon optical module market would grow from approximately US$455 million in 2018 to around US$4 billion in 2024 at a CAGR of 44.5%. According to Lightcounting, the overall data communication high-speed optical module market will reach US$6.5 billion by 2024, and silicon optical modules will account for 60% (3.3% in 20 years).

Intel, as one of the leading Silicon photonics companies, has a 60% market share in silicon photonic transceivers for datacom. Indeed, Intel has already shipped more than 3 million units of its 100G pluggable transceivers in just a few short years, and is continuing to expand its Silicon Photonics’ product offerings. And Cisco acquired Accacia for US$2.6 billion and Luxtera for US$660 million. Other companies like Inphi and NeoPhotonics are proposing silicon photonic transceivers with strong technologies.

Original Source: Silicon Photonics: Next Revolution for 400G Data Center

400G Optics in Hyperscale Data Centers

Since their advent, data centers have been striving hard to address the rising bandwidth requirements. A look at the stats reveals that 3.04 Exabytes of data is being generated on a daily basis. Whenever a hyperscale data center is taken into consideration, the bandwidth requirements are massive as the relevant applications require a preemptive approach due to their scalable nature. As the introduction of 400G data centers has taken the data transfer speed to a whole new level, it has brought significant convenience in addressing various areas of concern. In this article, we will dig a little deeper and try to answer the following questions:

  • What are the driving factors of 400G development?
  • What are the reasons behind the use of 400G optics in hyperscale data centers?
  • What are the trends in 400G devices in large-scale data centers?

What Are the Driving Factors For 400G Development?

The driving factors for 400G development are segregated into video streaming services and video conferencing services. These services require pretty high data transfer speeds in order to function smoothly across the globe.

Video Streaming Services

Video streaming services were already taking a toll on the bandwidth requirements. That, combined with the COVID-19 pandemic, forced a large population to stay and work from home. This automatically increased the usage of video streaming platforms. A look at the stats reveals that a medium-quality stream on Netflix consumes 0.8 GB per hour. See that in relation to over 209 million subscribers. As the traveling costs came down, the savings went to improved quality streams on Netflix like HD and 4K. What stood at 0.8 GB per hour rose to 3 and 7 GB per hour. This evolved the need for 400G development.

Video Conferencing Services

As COVID-19 made working from home the new norm, video conferencing services also saw a major boost. Till 2021, 20.56 million people have been reported to be working from home in the US alone. As video conferencing took center stage, Zoom, which consumes 500 MB per hour, saw a huge increase in its user base. This also puts great pressure on the data transfer needs.

What Makes 400G Optics the Ideal Choice For Hyperscale Data Centers?

Significant Decrease in Energy and Carbon Footprint

To put it simply, 400G raises the data transfer speed four times. 400G reduces the cost of 100G ports as breakouts when comparing a 4 x 100G solution to facilitate 400GbE with a single 400G solution to do the same. A single node at the output minimizes the risk of failures as well as lower the energy requirement. This brings down the ESG footprint that has become a KPI for the organizations going forward.

Reduced Operational Cost

As mentioned earlier, a 400G solution requires a single 400G port, whereas addressing the same requirement via a 100G solution requires four 100G ports. On a router, four ports cost way more than a single port that can facilitate rapid data transfer. The same is the case with power. Combined together, these two bring the operational cost down to a considerable extent.400G Optics

Trends of 400G Optics in Large-Scale Data Centers—Quick Adoption

The introduction of 400G solution in large-scale data centers has reshaped the entire sector. This is due to a humongous increase in the data transfer speeds. According to research, 400G is expected to replace 100G and 200G deployments way faster than its predecessors. Since its introduction, more and more vendors are upgrading to network devices that support 400G. The following image truly depicts the technology adoption rate.Trends of 400G Optics

Challenges Ahead

Lack of Advancement in the 400G Optical Transceivers sector

Although the shift towards such network devices is rapid, there are a number of implementation challenges. This is because it is not only the devices that need to be upgraded but also the infrastructure. Vendors are trying to upgrade them in order to stay ahead of the curve but the cost of the development and maturity of optical transceivers is not at the expected benchmark. The same is the case with their cost and reliability. As optical transceivers are a critical element, this comes as a major challenge in the deployment of 400G solutions.

Latency Measurement

In addition, the introduction of this solution has also made network testing and monitoring more important than ever. Latency measurement has always been a key indicator when evaluating performance. Data throughput combined with jitter and frame loss also comes as a major concern in this regard.

Investment in Network Layers

Lastly, the creation of a plug-and-play environment for this solution also needs to be more realistic. This will require a greater investment in the physical, higher level, and network-IP components layers.


Rapid technological advancements have led to concepts like the Internet of Things. These implementations require greater data transfer speeds. That, combined with the world going to remote work, has exponentially increased the traffic. Hyperscale data centers were already feeling the pressure and the introduction of 400G data centers is a step in the right direction. It is a preemptive approach to address the growing global population and the increasing number of internet users.

Article Source: 400G Optics in Hyperscale Data Centers

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FAQs on 400G Transceivers and Cables

400G transceivers and cables play a vital role in the process of constructing a 400G network system. Then, what is a 400G transceiver? What are the applications of QSFP-DD cables? Find answers here.

FAQs on 400G Transceivers and Cables Definition and Types

Q1: What is a 400G transceiver?

A1: 400G transceivers are optical modules that are mainly used for photoelectric conversion with a transmission rate of 400Gbps. 400G transceivers can be classified into two categories according to the applications: client-side transceivers for interconnections between the metro networks and the optical backbone, and line-side transceivers for transmission distances of 80km or even longer.

Q2: What are QSFP-DD cables?

A2: QSFP-DD cables contain two forms: one is a form of high-speed cable with QSFP-DD connectors on either end, transmitting and receiving 400Gbps data over a thin twinax cable or a fiber optic cable, and the other is a form of breakout cable that can split one 400G signal into 2x 200G, 4x 100G, or 8x 50G, enabling interconnection within a rack or between adjacent racks.

Q3: What are the 400G transceivers packaging forms?

A3: There are mainly the following six packaging forms of 400G optical modules:

  • QSFP-DD: 400G QSFP-DD (Quad Small Form Factor Pluggable-Double Density) is an expansion of QSFP, adding one row to the original 4-channel interface to 8 channels, running at 50Gb/s each, for a total bandwidth of 400Gb/s.
  • OSFP: OSFP (Octal Small Formfactor Pluggable, Octal means 8) is a new interface standard and is not compatible with the existing photoelectric interface. The size of 400G OSFP modules is slightly larger than that of 400G QSFP-DD.
  • CFP8: CFP8 is an expansion of CFP4, with 8 channels and a correspondingly larger size.
  • COBO: COBO (Consortium for On-Board Optics) means that all optical components are placed on the PCB. COBO is with good heat-dissipation and small-size. However, since it is not hot-swappable, once a module fails, it will be troublesome to repair.
  • CWDM8: CWDM 8 is an extension of CWDM4 with four new center wavelengths (1351/1371/1391/1411 nm). The wavelength range becomes wider and the number of lasers is doubled.
  • CDFP: CDFP was born earlier, and there are three editions of the specification. CD stands for 400 (Roman numerals). With 16 channels, the size of CDFP is relatively large.

Q4: What 400G transceivers and QSFP-DD cables are available on the market?

A4: The two tables below show the main types of 400G transceivers and cables on the market:

400G TransceiversStandardsMax Cable DistanceConnectorMediaTemperature Range
400G QSFP-DD SR8QSFP-DD MSA Compliant70m OM3/100m OM4MTP/MPO-16MMF0 to 70°C
400G QSFP-DD DR4QSFP-DD MSA, IEEE 802.3bs500mMTP/MPO-12SMF0 to 70°C
400G QSFP-DD FR4QSFP-DD MSA2kmLC DuplexSMF0 to 70°C
400G QSFP-DD 2FR4QSFP-DD MSA, IEEE 802.3bs2kmCSSMF0 to 70°C
400G QSFP-DD LR4QSFP-DD MSA Compliant10kmLC DuplexSMF0 to 70°C
400G QSFP-DD LR8QSFP-DD MSA Compliant10kmLC DuplexSMF0 to 70°C
400G QSFP-DD ER8QSFP-DD MSA Compliant40kmLC DuplexSMF0 to 70°C
400G OSFP SR8IEEE P802.3cm; IEEE 802.3cd100mMTP/MPO-16MMF0 to 70°C
400G OSFP DR4IEEE 802.3bs500mMTP/MPO-12SMF0 to 70°C
4000G OSFP XDR4/DR4+/2kmMTP/MPO-12SMF0 to 70°C
400G OSFP FR4100G lambda MSA2kmLC DuplexSMF0 to 70°C
400G OSFP 2FR4IEEE 802.3bs2kmCSSMF0 to 70°C
400G OSFP LR4100G lambda MSA10kmLC DuplexSMF0 to 70°C
QSFP-DD CablesCatagoryProduct DescriptionReachTemperature RangePower Consumption
400G QSFP-DD DACQSFP-DD to QSFP-DD DACwith each 400G QSFP-DD using 8x 50G PAM4 electrical lanesno more than 3m0 to 70°C<1.5W
400G QSFP-DD Breakout DACQSFP-DD to 2x 200G QSFP56 DACwith each 200G QSFP56 using 4x 50G PAM4 electrical lanesno more than 3m0 to 70°C<0.1W
QSFP-DD to 4x 100G QSFPs DACwith each 100G QSFPs using 2x 50G PAM4 electrical lanesno more than 3m0 to 70°C<0.1W
QSFP-DD to 8x 50G SFP56 DACwith each 50G SFP56 using 1x 50G PAM4 electrical laneno more than 3m0 to 80°C<0.1W
400G QSFP-DD AOCQSFP-DD to QSFP-DD AOCwith each 400G QSFP-DD using 8x 50G PAM4 electrical lanes70m (OM3) or 100m (OM4)0 to 70°C<10W
400G QSFP-DD Breakout AOCQSFP-DD to 2x 200G QSFP56 AOCwith each 200G QSFP56 using 4X 50G PAM4 electrical lane70m (OM3) or 100m (OM4)0 to 70°C/
QSFP-DD to 8x 50G SFP56 AOCwith each 50G SFP56 using 1x 50G PAM4 electrical lane70m (OM3) or 100m (OM4)0 to 70°C/
400G OSFP DACOSFP to OSFP DACwith each 400G OSFP using 8x 50G PAM4 electrical lanesno more than 3m0 to 70°C<0.5W
400G OSFP Breakout DACOSFP to 2x 200G QSFP56 DACwith each 200G QSFP56 using 4x 50G PAM4 electrical lanesno more than 3m0 to 70°C/
OSFP to 4x100G QSFPs DACwith each 100G QSFPs using 2x 50G PAM4 electrical lanesno more than 3m0 to 70°C/
OSFP to 8x 50G SFP56 DACwith each 50G SFP56 using 1x 50G PAM4 electrical laneno more than 3m//
400G OSFP AOCOSFP to OSFP AOCwith each 400G OSFP using 8x 50G PAM4 electrical lanes70m (OM3) or 100m (OM4)0 to 70°C<9.5W

Q5: What do the suffixes “SR8, DR4 / XDR4, FR4 / LR4 and 2FR4” mean in 400G transceivers?

A5: The letters refer to reach, and the number refers to the number of optical channels:

  • SR8: SR refers to 100m over MMF. Each of the 8 optical channels from an SR8 module is carried on separate fibers, resulting in a total of 16 fibers (8 Tx and 8 Rx).
  • DR4 / XDR4: DR / XDR refer to 500m / 2km over SMF. Each of the 4 optical channels is carried on separate fibers, resulting in a total of 4 pairs of fibers.
  • FR4 / LR4: FR4 / LR4 refer to 2km / 10km over SMF. All 4 optical channels from an FR4 / LR4 are multiplexed onto one fiber pair, resulting in a total of 2 fibers (1 Tx and 1 Rx).
  • 2FR4: 2FR4 refers to 2 x 200G-FR4 links with 2km over SMF. Each of the 200G FR4 links has 4 optical channels, multiplexed onto one fiber pair (1 Tx and 1 Rx per 200G link). A 2FR4 has 2 of these links, resulting in a total of 4 fibers, and a total of 8 optical channels.

FAQs on 400G Transceivers and Cables Applications

Q1: What are the benefits of moving to 400G technology?

A1: 400G technology can increase the throughput of data and maximize the bandwidth and port density of the data centers. With only 1/4 the number of optical fiber links, connectors, and patch panels when using 100G platforms for the same aggregate bandwidth, 400G optics can also reduce operating expenses. With these benefits, 400G transceivers and QSFP-DD cables can provide ideal solutions for data centers and high-performance computing environments.

Q2: What are the applications of QSFP-DD cables?

A2: QSFP-DD cables are mainly used for short-distance 400G Ethernet connectivity in the data centers, and 400G to 2x 200G / 4x 100G / 8x 50G Ethernet applications.

Q3: 400G QSFP-DD vs 400G OSFP/CFP8: What are the differences?

A3: The table below includes detailed comparisons for the three main form factors of 400G transceivers.

400G Transceiver400G QSFP-DD400G OSFPCFP8
Application ScenarioData centerData center & telecomTelecom
Size18.35mm× 89.4mm× 8.5mm22.58mm× 107.8mm× 13mm40mm× 102mm× 9.5mm
Max Power Consumption12W15W24W
Backward Compatibility with QSFP28YesThrough adapterNo
Electrical signaling (Gbps)8× 50G
Switch Port Density (1RU)363616
Media TypeMMF & SMF
Hot PluggableYes
Thermal ManagementIndirectDirectIndirect
Support 800GNoYesNo

For more details about the differences, please refer to the blog: Differences Between QSFP-DD and QSFP+/QSFP28/QSFP56/OSFP/CFP8/COBO

Q4: What does it mean when an electrical or optical channel is PAM4 or NRZ in 400G transceivers?

A4: NRZ is a modulation technique that has two voltage levels to represent logic 0 and logic 1. PAM4 uses four voltage levels to represent four combinations of two bits logic-11, 10, 01, and 00. PAM4 signal can transmit twice faster than the traditional NRZ signal.

When a signal is referred to as “25G NRZ”, it means the signal is carrying data at 25 Gbps with NRZ modulation. When a signal is referred to as “50G PAM4”, or “100G PAM4”, it means the signal is carrying data at 50 Gbps, or 100 Gbps, respectively, using PAM4 modulation. The electrical connector interface of 400G transceivers is always 8x 50Gb/s PAM4 (for a total of 400Gb/s).

FAQs on Using 400G Transceivers and Cables in Data Centers

Q1: Can I plug an OSFP module into a 400G QSFP-DD port, or a QSFP-DD module into an OSFP port?

A1: No. OSFP and QSFP-DD are two physically distinct form factors. If you have an OSFP system, then 400G OSFP optics must be used. If you have a QSFP-DD system, then 400G QSFP-DD optics must be used.

Q2: Can a QSFP module be plugged into a 400G QSFP-DD port?

A2: Yes. A QSFP (40G or 100G) module can be inserted into a QSFP-DD port as QSFP-DD is backward compatible with QSFP modules. When using a QSFP module in a 400G QSFP-DD port, the QSFP-DD port must be configured for a data rate of 100G (or 40G).

Q3: Is it possible with a 400G OSFP on one end of a 400G link, and a 400G QSFP-DD on the other end?

A3: Yes. OSFP and QSFP-DD describe the physical form factors of the modules. As long as the Ethernet media types are the same (i.e. both ends of the link are 400G-DR4, or 400G-FR4 etc.), 400G OSFP and 400G QSFP-DD modules will interoperate with each other.

Q4: How can I break out a 400G port and connect to 100G QSFP ports on existing platforms?

A4: There are several ways to break out a 400G port to 100G QSFP ports:

  • QSFP-DD-DR4 to 4x 100G-QSFP-DR over 500m SMF
400G to 4x 100G
  • QSFP-DD-XDR4 to 4x 100G-QSFP-FR over 2km SMF
400G to 4x 100G
  • QSFP-DD-LR4 to 4x 100G-QSFP-LR over 10km SMF
400G to 4x 100G
  • OSFP-400G-2FR4 to 2x QSFP-100G-CWDM4 over 2km SMF
400G to 4x 100G

Apart from the 400G transceivers mentioned above, 400G to 4x 100G breakout cables can also be used.

Article Source: FAQs on 400G Transceivers and Cables

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