Why 400G and why now?

By Nino Shaptoshvili, VP of Sales, PacketLight Networks

Exploring how 400G capacity per wavelength, together with next generation transponder/muxponder-based pluggable optics, satisfies today’s extreme bandwidth demands.

Driven by increasing global data demands, migration to 400G has become the latest milestone in optical fiber networking.

Even prior to the COVID-19 pandemic, traffic was growing at an exponential rate, propelled by increased device usage and the soaring bandwidth requirements of on-demand content, cloud applications, and more. This trend has only been amplified by the massive lifestyle changes that have taken place worldwide due to COVID-related lockdowns, as every home has been transformed almost overnight into an office, classroom, and entertainment complex. Even when the COVID crisis abates, there is no indication that data demands will revert to lower levels.

Networks therefore require technology that can support these fast-paced changes, both today and in the future. The 400G transition represents not only larger capacity but also a shift in infrastructure requirements that will define network connectivity for generations to come. Needless to say, dependable data capacity is a must for any business seeking to maintain its competitive standing. 

This article addresses the challenges and opportunities awaiting the telecom industry as it faces these massive traffic increases and learns to flourish within the 400G era.

What is 400G?

400G capacity over a single wavelength technology is suitable for new and expanding network infrastructures, enabling fiber optic networks to handle the ever-heavier burden of increasing data volumes. The 400G standard doubles today’s 200G capacity, and is designed to address current and future bandwidth needs, reducing the cost per transported bit.

Going forward, overall data consumption is estimated to rise by more than 50% per year, with massively increasing remote working/learning and streaming entertainment (with the COVID-19 pandemic expanding these estimates still further). In hyperscale data centers, data capacity needs are doubling every year. Given the surging popularity and data requirements in almost every area of business and home life, including IoT technology and 5G network infrastructure, these estimates will only be surpassed. In this global environment, 400G is set to thrive, increasing spectral efficiency for data centers and network carriers, and enabling them to support diverse data-intensive applications.

What were the initial challenges of 400G?

As with most technological advances, major and minor, the early days of 400G migration posed challenges related to higher costs, lack of standardization, increased power/cooling demands, requirement for more rack space, and less flexibility. Although some large businesses opted to jump on the train of early-adopters, most of the market waited for standardized, pluggable technology to be introduced.

Over the past year or so, the challenges associated with upgrading to 400G have been resolved through the introduction of a new generation of 400G pluggable optical modules such as CFP2-DCO and QSFP-DD. Pluggable optics have made it possible for organizations of all sizes to easily make the leap to 400G, by offering them the flexibility to evaluate business needs and plan accordingly.

How have pluggable modules helped make the leap to 400G possible?

The use of pluggable modules introduces simplicity and reliability to the challenge of increasing capacity, while also reducing maintenance/support needs and power consumption. Traditional non-MSA 400G modules were the basis for many of the initial challenges associated with 400G migration. They exhibited high power consumption and low performance, while not lending themselves to flexibility and interoperability.

Pluggable modules easily increase capacity, significantly reduce power consumption, simplify maintenance and support, and enable real pay-as-you-grow architecture with convenient plug-and-play functionality through front panel access. The standards-based pluggable modules also deliver enhanced performance and flexibility, while eliminating lingering compatibility and lock-in issues.

These factors can be seen in the latest CFP2 and QSFP-DD 400G modules, which have transformed the industry (see table below), with <24W power consumption (versus >65W), OFEC/CFEC interoperability (versus a proprietary standard), pluggability via the front panel, and multiple MSA sources.

With the dawn of these pluggable modules, vendors have introduced a new generation of 400G transponders and muxponders that allow large and small enterprises to take advantage of these optics to reduce the build or expansion cost of their optical transport network.

 

* Module photos courtesy of Finisar/II-VI 

These modular, interoperable devices maximize the value of existing infrastructure and connectivity. Enabling cost-effective rollout and expansion, they allow easy, instantaneous maintenance or replacement of individual parts. If one module develops a fault or has to be upgraded, it can simply be pulled out of the slot and replaced, without replacing the entire box or taking it offline. This not only is important in terms of usability, but also has a huge impact on overall performance, avoiding downtime and complications for users, and ultimately on cost.

What are the primary considerations and capabilities involved with 400G migration?

When undertaking any expansion of fiber optic network capacity, there are certain considerations that must be addressed. Foremost among them is the need to save costs, which is reflected in real estate usage, power consumption, and migration speed. However, it is the issue of flexibility that has become paramount for data centers, service providers, and other clients seeking improved adaptability and ease of use.

This is especially so in 400G, as there is a demand for a much smaller footprint and significant reductions in power requirements throughout all optical network infrastructure that must be able to support 400G capacity.

Currently, vendors offer products designed to fulfill these demands, including OTN transponders, muxponders, and other infrastructure requirements (Erbium-doped fiber amplifiers, Raman amplifiers, fiber diagnostics, WSS ROADM, passive solutions, etc.), with an impressively thorough list of features. These 400G products support a flexible variety of the latest 400G line optics, such as high performance CFP2-DCO – OpenROADM, QSFP-OpenZR+ and QSFP-ZR, and different standard FEC modes such as C-FEC as defined by the OIF, O-FEC as defined in the OpenROADM standard, and SD-FEC for high performance demanding links. The CFP2 pluggable module used in these devices also provides ultra-long-haul connectivity for 200G wavelengths.

Full performance monitoring and visibility of the optical transport layer (OTN), as well as Ethernet, Fibre Channel and OTN service interfaces, are enabled through OTN muxponders and transponders. These support 10/25/100/400Gb Ethernet, 16/32G Fibre Channel, and OTU2/OTU4 services and rates over a single 400G wavelength.

Few selected vendors have been able to deliver 400G solutions in a 1U format factor, responding to those real estate usage concerns as well as consuming far less power. In this format, muxponder and transponder operation modes are expandable to 64 channels across a robust, scalable, redundant, and low latency solution. This modular, cost-effective solution delivers better performance in less space with lower cost per bit, optimizing the link budget and supporting standard forward error correction (FEC) modes for interoperability. It can support up to four 400G DCO pluggable uplink optical modules, delivering up to 1.6T in a 1U chassis, with integrated 4:1 mux/demux, 1 or 2 EDFA modules and OSW, and access to the entire optical layer.

We discussed with Koby Reshef, CEO of PacketLight Networks, a leading DWDM and OTN vendor in 1U devices, what it means to have 400G capacity in 1U form factor.

“The introduction of pluggable optics has allowed us to offer our customers up to 1.6T capacity in a 1U integrated solution, without compromising on any of our carrier-grade features. The 1U form factor is important, as it responds to cost and power consumption concerns, and delivers a robust, scalable, redundant, and low latency solution. The modular solution offers high performance with lower cost per bit, optimizing the link budget, and supporting standard forward error correction (FEC) modes for interoperability. Additionally, we support Layer-1 encryption based on GCM-AES-256 standards and Diffie-Hellman (DH) Key Exchange, and protection against fiber cut or equipment failure.”

So, where do we go from here?

As 400G technology is maturing under circumstances of unprecedented growth and demand, it is under great pressure to be all things to all people and address the different challenges that different organizations face. The 400G portfolio now offered by leading vendors is explicitly designed to accommodate a broad range of use cases and configurations, with modular devices that are interoperable with third party network infrastructures.

These use cases evidence the flexibility of the solution, with 400G metro and long-haul network applications of up to 1,200km, as well as 200G long-haul applications of up to 2,500km, high-capacity DCI for campuses and cloud networks, last-mile access CPE for 100GbE managed services, and so on.

Next-generation transponders and muxponders based on pluggable optics ensure that future 400G capacity upgrades will maintain the flexibility, modularity, and power-saving capabilities that network operators have become accustomed to over the years. This technology also eliminates vendor lock-in and allows for the easy expansion of existing network capacity without replacing hardware. It can even allow companies to upgrade existing networks to 400G rather than starting again from scratch, which has immense cost and functionality implications for both current and future applications.

The next generation 400G muxponders/transponders coupled with pluggable optics are the solution that answers the questions of “why 400G and why now?” while putting the data industry in a good position to tackle the many demands of tomorrow.