Driving Innovation with Optics for 400G and Beyond

Demand for 400G is increasing exponentially as both core and edge network use cases continue to demand increased bandwidth over greater distances. At the same time, metro data center interconnects are driving increased aggregation and network simplification as the demands of the digital economy continue to mount.

Amid all of this, of course, network operators are under pressure to keep costs to a minimum without inhibiting flexibility and scalability, both in today’s networks and those under development.

Upgraded and optimized

This is why many operators are turning to 400G coherent optics as a key building block in their network modernization strategies. Not only can pluggables support both 400G architectures and beyond, but they do so at reduced costs from traditional optical networks by converging IP and optical networks and embedding optical transponders in routers and switches. This is leading to nothing less than a new era in transport technology based on this vertical convergence of IP and optical networking that will reduce network complexity, simplify operations, increase network sustainability, and ultimately lower overall total cost of ownership (TCO).

Coherent pluggable optics are proving to be highly beneficial to today’s networking environments. With all the latest network use cases -- such as metro, regional, data center interconnect (DCI), core, and both long-haul and ultra-long-haul -- requiring increased capacity, reach, and resiliency, as well as the need to connect to IP networks, coherent DWDM at the router and switch is becoming essential. To achieve this, designers are using IP over DWDM (IPoDWDM) to convert router Ethernet signals to DWDM and then multiplex them with other DWDM channels on a single fiber. This approach greatly reduces the optical network footprint by eliminating the need for external DWDM transponders.

IPoDWDM architectures have been around for 20 years; however, 400G coherent pluggable optics technology has advanced to take advantage of small-form-factor designs that enable greater flexibility in network designs so they can be mixed and matched with other pluggable optics on the same line card without affecting overall platform density. Both the new generation of coherent DWDM transceivers and QSFP56-DD pluggable optics allow short- and long-distance (400 LR4 and 400ZR or ZR+) grey client interfaces to be arranged on a port-by-port basis, all of which enables integrated optical routing and switching on access, edge, and core networks.

From an operational standpoint, this kind of flexibility enables a high degree of service agility. For one thing, 400G ZR coherent pluggable optics, defined by the OIF, supports metro DCI use cases. On the other hand, 400G ZR+ supports a number of channelization modes defined under OpenZR+ Multi-Source Agreement (MSA), including 1x400 and 4x/3x/2x/1x100G. Depending on the reach and bit rate required, this flexibility serves the various needs, including 400G metro, 300G regional, and 200G and 100G long-haul applications – all from a single pluggable optic device.

While this multi-rate ability dramatically reduces the cost of physical infrastructure, it also plays a key role in streamlining operational control through the use of enhanced management and automation capabilities. One of the key issues operators face today is the fact that optical transponders within a line system are managed by separate, usually proprietary, software solutions. Not only does this fact disincentivize vendors from deploying unified NMS tools, but it also inhibits the use of converged management controllers that could place the entire control stack under a single-pane user interface.

Smart and savvy

Convergence essentially provides the means to implement a standards-based network management stack that provides multilayer, multidomain orchestration using telemetry data from IP and transport controllers. In addition, it enables the kind of operational intelligence and heightened service visibility needed to predict and resolve network anomalies through root-cause analysis and active mitigation.

It is important to note, however, that even though optical and IP networks are converged, their respective management teams can still maintain traditional oversight of their domains. Distinct software control stacks enable engineers in both groups to access, modify, and test their networks as they always have, while still preserving the ability to collaborate when necessary to work out integration issues and continually strive to refine and enhance the converged model.

Yet another key factor in these emerging IPoDWDM architectures is their support for broad interoperability and open networking. Using industry standards like OIF ZR, OpenZR+ MSA, and CMIS (Common Management Interface Specification) as the host interface, operators are able to craft best-in-breed architectures that support highly specialized use cases and multi-vendor ecosystems. With many suppliers still facing supply chain issues and other challenges in the post-pandemic world, open technologies make it easier to locate and deploy critical solutions quickly and at lower costs.

But perhaps the most crucial benefit of this type of converged architecture is its impact on environmental and network sustainability. By using 400G coherent optics and removing optical transponders, network operators dramatically lower their power, resource, and space requirements. Some deployments, in fact, have exhibited power reductions on the order of 40% over traditional line systems, which not only lowers operating costs but can deliver significant reductions to a network’s carbon footprint. At the same time, they achieve higher metrics for reliability, operational efficiency, and other key factors.

As the digital economy continues to evolve, more enterprise and consumer data will make its way to distributed data center and cloud-based resources, which are already available at scale and at reasonable price points. This means there will always be a place to store and process data, putting responsibility for overall performance on the network.

Pluggable devices that support the latest coherent technologies offer a quick, cost-effective way to take networking to the next level and then continue to push the envelope as data demands increase. In a world where performance no longer depends on how much data you have but on how quickly you can move it from place to place, a streamlined network that boosts speed, capacity, and management capabilities all at once is the best resource you can have.

Julius Francis is senior director of product marketing and strategy for security, automation, and networking at Juniper Networks.