In a 2021 ACG Research report, service providers were asked to estimate the compound annual growth rate (CAGR) of capacity in various segments of their networks through 2025. The results ranged from 39% in submarine networks to 46% in residential broadband. Elevated traffic growth has been the norm throughout the last two years of the COVID-19 pandemic, and this data implies that the trend will continue beyond its immediate impacts. Traffic growth is at the heart of my 2022 predictions. Service providers must cost-effectively increase networking capacity and evolve their networks to keep up with traffic growth that is doubling approximately every two years. To do so, they will lean into new technologies and approaches in optical networking.
#1: Coherent Starts Its Move Toward the Access Edge
Like wireless networks, coherent DWDM optical technology utilizes higher baud rates, advanced modulation schemes (for example, 64 QAM or quadrature amplitude modulation), and digital signal processing to achieve higher data rates of transmission. Alternatively, direct-detect optical transmission technology utilizes simpler, intensity-modulated on/off keying to transmit a data stream as a sequence of binary ones or zeros, respectively, and does not require sophisticated digital signal processing. Direct-detect technology can transmit 10G and 25G DWDM optical signals tens of kilometers in pluggable form factors like SFP/SFP+. It is thus common for the access edge of the network to utilize direct-detect pluggable optical technology and for the metro optical network to be the starting point for coherent DWDM utilization.
However, as capacity growth continues, the connectivity at the access edge of the network for 5G radios, broadband fiber, and cable access networks will transition from 10G/25G to 100G interfaces. This transition will help push coherent DWDM pluggable optics out of the metro and into the access edge. To remain economical and provide flexible and efficient bandwidth utilization at the edge of the network, technologies like XR optics, which enables many lower-speed 100G pluggable optics to talk directly and simultaneously to a single 400G or 800G high-speed optic, are emerging. Utilizing 25G digital subcarriers, XR optics enables up to 16 x 25G connections to a single high-speed optic – thus enabling a point-to-multipoint architecture, over fiber pairs or single-fiber working, that can eliminate intermediate electrical aggregation and reduce the number of pluggable optics by almost 50%, and thus reduce total cost of ownership by more than 70%. While direct-detect technology will remain dominant in the near term, 2022 will see service providers planning for coherent DWDM pluggable optics’ move toward the access edge.
#2: 400G ZR+ - Not So Fast Yet
There is no denying that 400G pluggable optical engines have made great strides in increasing their optical performance while reducing power and size with support for CFP-2 and QSFP-DD packages. While 400G ZR is well defined to support very specific tasks, like point-to-point data center connectivity at 120 km or less, 400G ZR+ has a broader definition and set of capabilities and use cases depending upon which vendor or ecosystem is involved. In 2022 we see service providers identifying and testing use cases for 400G ZR+ pluggables, but we believe the ramp will not happen as fast as some previously predicted, and most early deployments will occur in conjunction with optical networking equipment instead of directly into routers. Part of the reason for this is that in the near term, higher-performance 400G ZR+ pluggables with higher transmit power (for example, 0 dBm vs. -10 dBm for 400G ZR) that are applicable for multiple applications, including metro transport with a high number of ROADM cascades, will be in the CFP-2 form factor. The larger CFP-2 package has room to boost optical performance; however, it reduces router faceplate density and will thus lead to more deployments with compact modular optical platforms than in routing. Additional innovations like subcarrier-based XR optics, higher levels of vertical integration, and utilization of indium phosphide substrate for pluggables will continue to enhance the capabilities of QSFP-DD pluggables, including delivering higher launch power and performance, which will then lead to greater router adoption over time.
#3: 800G Goes Big
Accelerating adoption of 800G coherent DWDM embedded optical engines like Infinera’s ICE6 will help network operators cost-effectively address growing capacity demands for their optical transport networks in 2022 and beyond.In a recent study by ACG Research, 78% of service providers indicated that they would deploy 800G coherent by the end of 2022. The combination of programmability and advanced technologies like 96 Gbaud symbol rates, second-generation digital subcarriers, and long-codeword probabilistic constellation shaping is enabling industry-leading performance at 800G and 700G vs. prior generations at 600G and 400G. Programmability also means 800G transmission technology is applicable to more networks at any reach, including fixed- or flexible-grid channel spacings and legacy or modern fiber optic cables. The ability to provide increased capacity per fiber with fewer wavelengths and less equipment creates compelling economics for accelerated 800G coherent adoption in submarine, long-haul, DCI, and metro networks with limited fiber availability.
#4: Open Optical Networking Becomes a Requirement
With more optical engine technologies deployed in more diverse environments and network elements, including routers, switches, and transponders, more network operators will lean into open optical networking in 2022. With open optical networking, service providers get more choice, faster innovation, and improved economics. And in a world with supply chain challenges, open optical networking may become an imperative by enabling service providers to source optical engine and transponder technology from multiple suppliers and thus improve supply continuity.
#5: Compact Modular Takes On Multiple Personalities
One of the fastest growing segments in optical networking is compact modular platforms like Infinera’s GX Series. Such networking platforms tend to be one, two, or three rack units in height and accept insertion of one to four sled-based modules per row. Increased modularity and pluggability enable both pay-as-you-grow and power-as-you-grow capabilities. These platforms began in 2015 as disaggregated transponders for deployment predominately by internet content providers (ICPs). More recently, new form factors and capabilities such as 450-mm or 300-mm depth, full NEBS compliance, and redundancy options such as redundant controllers have emerged to further expand deployment into many networking environments, including traditional communication service provider (CSP) networks. To date, we have mostly seen dedicated optical line systems separate from the compact modular transponders. In 2022 and beyond, we anticipate a more universal platform approach emerging – where the same platform will have a full complement of line system sleds like ROADMs and amplifiers as well as transponders, muxponders, and switchponders. Such an approach will simplify operations by enabling the same compact modular platform and the same microservices-based software architecture to take on multiple personalities depending upon the configuration and modules deployed.
2021 has been another challenging year, but it has also reinforced the importance of our networks for entertainment, education, work, and mental and physical health. With advances in 800G embedded optical engines, 400G pluggable optics, and migration to compact modular platforms, as well as an embrace of open optical networking, I am incredibly excited about the future of optical networking in 2022 and beyond. In closing, I wish you all the best for a safe and successful 2022.
