Transforming Enterprise Optical Transport with Data Center Interconnect (DCI)

Summary Bullets:

• Webscales, ICPs, and enterprises are using DCI solutions to provide high-quality, practically unlimited connectivity for their data centers, while controlling their costs through building up their own infrastructure.

• DCI vendors need to develop their solutions considering not only the connection capacity requirements, but also the increasing demands on O&M simplification, intelligence, and security.

DCI solutions have evolved, driven by the incessant growth of cloud, which will continue well into the future. According to GlobalData’s market sizing and forecast, the global cloud ecosystem expanded 24% in 2018 and reached US$ 290 billion; it will continue to grow with CAGR of 25.3% over the forecast period, reaching US$720 billion in 2022. The first use for DCI has been in providing point-to-point connectivity for large centralized data centers. But as data centers keep getting deployed throughout the network footprint – all the way to the network edge itself in edge computing installations – the demand for simple, high-performance optical solutions keep growing as well.

The reasons for this trend have become relatively clear in the recent years. The primary driver for DCI market demand, and, consequently, DCI equipment design, has been the desire of early adopters, primarily webscales, to deploy very high bandwidth connections, on owned or leased fiber, while controlling their costs, and gaining ability to scale up (or down) their connectivity as and when needed – very rapidly. Additionally, DCI users increasingly require low latency/high quality connections to improve performance of their mission-critical applications and their Internet content user experience. DCI platforms also need to satisfy an increasing spectrum of requirements stemming from cloud data center decentralization – for large installations they need to be deployed in stacks, their line interfaces multiplexed for maximum fiber utilization, capacity, and reach; for smaller data centers and edge cloud installations, they need to pack as much capacity as possible in a small chassis, and preferably feature a modular design, which allows to set up the initial connection with optimized cost, and then scale if and as bandwidth requirements increase. Finally, even though DCI platforms are inherently simpler to deploy and operate than traditional optical equipment, DCI users require to simplify their O&M processes, to be able to quickly deploy/tear down services and perform other operations and management tasks more intelligently, without increasing their network related headcount and OpEx.

With these requirements in mind, the DCI design has evolved to feature the following characteristics:

Maximized Fiber Utilization Using High Wavelength and Per-Fiber Capacity Solutions: Leading DCI solutions today feature the use of 400G and 600G wavelength capacities, with vendors developing coherent solutions that will allow for 800G per wavelength on short distances in the future. Additionally, modern DCI platforms use coherent solutions that feature ability to choose modulation schemes to achieve optimum wavelength capacity for a given span and fiber characteristics dynamically. The fiber utilization can further be enhanced using extended C-band (increasing number of usable channels by using wideband optical amplifiers) or C+L spectrum bands for optical transport.

Throughput Density and Power Efficiency: From the onset, DCI platforms were also measured by their throughput density (throughput capacity per rack unit) and their power efficiency, usually measured in W/Gbps of throughput capacity. Leading solutions today achieve 4.8Tbps per 1RU and less than 0.3W/Gbps power consumption.

Physical Characteristics and Modularity: Another very important factor in compact modular platform design is the adherence to design principles used in data center equipment development. Most DCI platforms today are 1RU-2RU high “pizza boxes” featuring front-to-back airflow. Additionally, the leading platforms in the second generation of DCI solutions that currently represent most of the market feature an internally modular design that allows combining transponder/muxponder modules or sleds with optical line system elements, for maximum versatility and flexibility, especially in smaller data center environments. DCI platforms integrate several traditional optical line modules into one avoiding complicated patch-cord connections, thus simplifying and accelerating provisioning processes.

Intelligent and Automated O&M Processes: AI also plays an important role in O&M, providing benefits such as reduced mean time to response (MTTR), faster root cause analysis (RCA), and increased O&M productivity. The focal point in DCI platforms’ management and automation development is implementing AI utilizing both hardware and software elements in support of simplified and automated O&M. This entails modern AI-based, cloud-native management and control suites that allow for automatic equipment and service provisioning, and implementation of AI-driven predictive analytics, proactive maintenance, optical system health prediction, and other deep learning functions. AI technologies enable O&M teams to minimize low-value repetitive tasks and free up time for more value-added actions.

Security: As most DCI solutions are used to carry sensitive and mission critical traffic between data centers, users have from the beginning put emphasis on pervasive security that DCI solutions must fulfill. This has primarily meant that DCI solutions needed to feature line-side L1 encryption with as little overhead as possible, and today’s leading solutions provide that functionality at all wavelength speeds available on the equipment. Additionally, leading solutions provide client-side AES 256 encryption as well.

Future development of the DCI solutions will be – again – driven by the evolving nature of cloud services and infrastructures. As the cloud decentralizes, the DCI systems, as well as the associated optical line systems, will need to develop into even more versatile universal optical transport platforms, capable of satisfying diverse customer needs, from supporting very high-capacity point-to-point connections, to participating in mesh infrastructures connecting distributed and edge cloud data centers. These demands dictate several primary directions of DCI solution development, including:

Cost Control and Optimization: As future DCI solutions develop to support smaller, distributed DC deployments and other applications, they will need to improve their support of modular coherent solutions (CFP-2 ACO/DCO) in addition to currently preferred high-performance discrete solutions. This will serve to increase the attractiveness of compact modular DCI systems for non-webscale enterprise and government users, providing compelling cost control and OpEx reduction benefits. Further integration of transponder/muxponder parts of the solution, and optical line system functionality will be required as well – this can also work to simplify the O&M workload, which stays one of the key requirements on DCI in the future.

AI Implementation: Future DCI systems will be deployed in more complex, fluid, and diverse environments, connecting apps that migrate across network domains. This puts emphasis on developing modern AI-based automation systems that will enable dynamic and automatic network and service provisioning, predictive health, maintenance, and change management, as well as enhancing the efficiency and precision of O&M processes.

Openness: DCI systems should also expose their capabilities to northbound orchestration using open industry-standard APIs, to ensure seamless interoperability between different network domains. DCI platforms must evolve toward higher level of openness, enabling customers to choose different elements of their software and hardware environments.

Key Takeaways

Think Beyond Capacity: Enterprises considering DCI should look beyond headline wavelength capacities and examine the capacity/reach results that new DCI solutions can help achieve on their existing or planned fiber plant; additionally, they should evaluate vendors’ ability to address expanded spectrum within the fiber, either by utilizing extended C-band, or C+L band.

Examine Benefits of AI and Automation: Most DCI buyers have experience with automation in their data center environments. They should now examine DCI solution automation benefits and plan for introducing AI to further optimize use of their optical transport networks and introduce end-to-end automation spanning data center networks, IP networks, and optical transport.

Think Beyond TCO: Enterprises should look at the TCO of the solution, but should also evaluate benefits DCI brings beyond simple cost reduction – flexibility and scalability, highest security levels, practically unlimited capacity, and control over latency and other connection parameters.

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