RADHA NAGARAJAN 400G DCI
Figure 2: 400G 16QAM DWDMQSFP-DD pluggable module for DCI
Extended performance beyond ZR to ZR+: For end users that need performance beyond 400ZR, today’s 7nm coherent DSPs offer multiple reach and data rate options for metro and long-haul performance. This gives cloud and telecom providers the option to extend 400G reach while also spanning lower data rates to thousands of kilometres on their metro and long-haul networks. Figure 3 shows how 100G is now expected to evolve to a 400G infrastructure using a next-generation 400G coherent QAM. The latest technology advances are enabling a seamless transition to 400G in the DCI infrastructure, increasing density while slashing both power dissipation and the cost per bit to unprecedented levels. New 400G ZR and ZR+ DCO modules will deliver a unique value proposition for cloud and service provider customers and be supported on standard switches and routers for DCI, metro, and even long-haul DWDM networks. This will accelerate the adoption of 400GbE with 400G ZR and ZR+ across multiple platforms, enabling service providers, cloud and enterprise customers to transition to 400G for lower cost per bit and increased bandwidth while achieving better economics with no density/throughput trade-off for packet-optical integration. LOOKING AHEAD What will follow is a massive increase in switch rack capacity -- as much as 4-6 times more throughput per chassis -- while reducing power consumption by as much as 80 percent. Cloud end users will be able to dramatically lower the cost of scaling out their cloud data centres around the globe. Meanwhile, as cloud service providers continue to scale for rapidly increasing bandwidth demands with lower latency for their customers, the trend towards distributed regional data centre architectures will accelerate and provide numerous advantages including higher resilience and availability for end users.
for 120 kilometres reach DCI applications: CFEC is an extension of the Staircase FEC adopted by the IEEE and ITU. New economic model: Cloud operators can now connect metro data centres at a fraction of the cost of traditional coherent transport systems. As the underlying 7nm silicon geometry delivers over 75 percent reduction in DSP power dissipation and size as compared to the current generation of coherent DSPs, it will spur a new generation of pluggable modules that enable cloud end users to dramatically lower the cost of scaling out their cloud data centres worldwide. This in turn will help accelerate the trend toward distributed regional data centre architectures. This more distributed architecture within each metro region as compared to traditional huge data centres residing in single campus facilities will provide advantages including higher resilience and availability for end users. Eliminating a layer of network connectivity: Switch and router companies can now offer the same density for both coherent DWDM and client optics in the same chassis, eliminating a layer of network connectivity that was previously required while supporting high-capacity DWDM connectivity directly from data centre switches.
technology options that better facilitate the move to 400G ZR while providing the ability to select either the power optimised ZR or high-performance modes so modules can cover a wide range of network applications. Also, as these DSPs moved to 7nm silicon geometry, it has become possible to achieve the reduced power dissipation and size that are required for small form factor pluggable modules. A first example of solutions that use this type of DSP architecture for cloud DCI is the Inphi COLORZ II 400ZR QSFP-DD transceiver (see Figure 2). It introduces the opportunity to leverage a multi-vendor, industrywide ecosystem that eliminates the risk of getting locked into proprietary single vendor solutions. Establishing a new, multi-vendor, industrywide ecosystem has numerous important implications for the next generation of 400G DCI deployments: Interoperability: A large ecosystem of system and module OEMs using the same coherent DSP architecture in QSFP-DD, OSFP and CFP2-DCO modules will allow for interoperability between transceivers and even for extended reach modes.
Industrywide adoption of concatenated FEC (CFEC) technology by the OIF, IEEE and ITU
Figure 3: 100G evolution to 400G infrastructure, Mark Filer, Microsoft Corp.
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ISSUE 20 | Q1 2020
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