Optimizing open line systems to support 400G Anywhere
What do automobile engines and coherent digital signal processors (DSPs) have in common? They are both at the heart of their respective system architectures and they get most of the attention, R&D investment and headlines. But other system components affect overall system performance, too.
For automotive design, you need to match the drivetrain and operating system with the capabilities of the engine to maximize price–performance ratio for the driving application, whether it’s a high-performing luxury touring sedan or an economical commuter subcompact. The same is true for optical transport networks, especially in open optical systems that mix and match disaggregated hardware and software components from multiple vendors. What good is an engine that is over-powered for most driving conditions, or a drivetrain that can’t handle its torque? Likewise, what good is a line system based on classic, fixed ROADMs that can’t take advantage of the programmable multimodulation schemes of today’s coherent DSPs? You need to optimize price and performance for the given application.
Like automobile engines, coherent optics and the DSP technology they rely on are rapidly advancing. New product generations appear every 12 to 18 months. Integration and innovation are improving the price–performance of coherent DSPs relative to cost per bit, capacity–reach performance, power dissipation and packaging format.
So while an engine designed for a Ferrari may bring adrenaline-inducing speeds to a select few, it’s more relevant to the masses to have an engine that performs well for the majority of day-to-day driving activities. In the optical world, the relevant metric is enabling cost-efficient transport for the next generation of 400 Gigabit Ethernet (400GE) services over any distance and across all applications.
Network operators will need multiple coherent optics solutions to support 400G transport for a broad range of applications and use cases. These solutions include:
- 400ZR pluggable digital coherent optics (DCOs) based on the Open Internetworking Forum (OIF) interworking specification, which allow network operators to consider router-to-router-based IP over DWDM architectures for point-to-point data center interconnect (DCI) applications over short distances up to 120 km
- 400ZR+ coherent pluggable optics, which are non-standard extensions that broaden the 400ZR IP over WDM application space to support point-to-point DCI links up to a few hundred kilometers long, as well as metro access and aggregation rings
- 400G Multihaul pluggable DCOs, which provide improved capacity–reach performance over 400ZR+, enabling much broader use across ROADM-enabled metro aggregation rings and metro-regional core networks. The CFP2 format of 400G Multihaul enables integration into transponder formats and routers.
- High-baud-rate (>90 Gbaud) coherent optics that are optimized for maximum capacity–reach and available in transponder formats, which enable operators to use 400G Anywhere in regional, long-haul and subsea applications that span hundreds to thousands of kilometers
Pluggable DCO modules, along with standard, open application programming interfaces (APIs) and data models, are enabling disaggregation of network functions. Disaggregation allows operators to source coherent optics in different formats from different vendors. They can operate these optics over open line systems to optimize end-to-end performance for a wide range of network applications, from metro access to meshed metro cores and long-haul backbones.
Coherent-optimized open line systems are essential for maximizing application performance and overall return on investment (ROI). They deliver optimal scalability, agility and efficiency over the entire deployment lifecycle. To efficiently transport data from point A to point B, they must be complemented with navigation and operating systems that can manage complex operations, many of which are programmed and automated.
The 10–15 year deployment cycle of optical line systems — compared to 2–5 years for coherent transponders or terminals — presents a challenge in optimizing system performance and meeting overall ROI objectives. Longer-lifespan line systems, especially open line systems, must be modular, versatile and extensible to support many generations of open terminals and future network upgrades.
Disaggregated open line system platforms in new or upgraded networks should support the full capabilities of a range of coherent optics choices. They should also take advantage of a broad range of line system features, including reconfigurable optical add-drop multiplexers (ROADMs), erbium and Raman amplification, optical protection switching and C+L band options for maximizing fiber capacity. At the same time, they should support several generations of coherent optics from multiple vendors.
Today’s open, disaggregated line systems provide essential features such as:
- A flexible, data center-optimized form factor with front to back airflow design, AC or DC modular power supply options, and flexible data center and telco mounting options
- A modular, function-optimized architecture that leverages common platform hardware, including ROADMs, amplifiers and add/drop modules
- Open programmability enabled using simplified management and SDN control with industry-standard open APIs and protocols
- Alien wavelength support
Operators seeking to optimize network performance with advanced line system technology also require next-generation ROADMs that support a range of transmission bands and add/drop options, including:
- C+L band WDM transmission to double network capacity
- High-degree Colorless–Flexgrid (C-F) and Colorless Directionless Contentionless – Flexgrid (CDC-F) to match programmable DSP modulation capabilities
- DCO-optimized add/drop options, especially for 400ZR+ applications
In addition, these operators need flexible and customizable equalized inline amplifier (E-ILA) EDFA and Raman-EDFA options that will enable them to save CAPEX and OPEX by replacing conventional wavelength selective switch (WSS)-based dynamic gain equalization (DGE) nodes and ILAs.
To optimize price–performance for an open optical network system design, an operator should choose an open line system that meets these criteria while maximizing the performance of the DSP engine. The operator should also ensure that the open line system comes with an open operating system controller and application software that provide the flexibility and programmability it needs to leverage these capabilities in the network.
The Nokia 1830 Photonic Service Interconnect – Line (PSI-L) system is optimized for coherent applications. It provides capabilities that maximize optical transmission performance across a range of disaggregated, multivendor architectures. It can be paired with 400G DCO-based transponder pluggables and modules powered by Nokia PSE-V DSP to provide optimal price–performance.
The Nokia Network Services Platform (NSP) and Nokia WaveSuite Network Optimizer and Service Enablement software applications complement the solution with multivendor management and control automation capabilities. Together, they help transform networks into automated, high-value service engines with maximum scalability, reduced OPEX and accelerated ROI.