The Benefits of Multirate Coherent Transponders in CFP2 Form Factor
The exponential growth of content delivery and enterprise cloud service delivery, combined with the promise of future 5G wireless-based services for consumers, the IOT, and connected vehicles worldwide, will create unprecedented increases in network traffic across all access, edge, and core networks.
To meet the imperative need for higher capacity and providing the best user experience, the operator and product development communities must accelerate roll-out of the networks of the future. On top of providing the best performance at the lowest operating cost per bit, they also have to enable attributes such as on-demand and scalable capacity, high efficiency, and intelligence through simple, fully-configurable, and automated network elements.
On Lowest Cost per Bit, Performance, and Scalability
The last five years have seen an evolution toward optimized network topologies and link specifications for distinct uses cases. These can be grouped into two main categories:
Metro and Long-Haul Transport
Metro and Long-Haul Transport, which includes service provider optical transport, private cloud hyperscale data center interconnect (DCI), and the burgeoning education/ research and colocation DCI applications. In this category, transport DWDM links are amplified and can be point-to-point single span over 80 km (see Figure 3) or feature multiple spans for reaches over thousands of kilometers (both point-to-point and ring-based with ROADMs). DCI applications include both metro and long-haul transport links, which require the highest density combined with low power and maximum performance to achieve the lowest cost per bit. Similar to edge aggregation, using pluggable modules such as the current 100/200 CFP2-DCO or 400G pluggable modules in the near future, permits the integration of the optical layer in the edge router platform instead of the more traditional segmentation where routing and DWDM/optical functions are segregated.
It should be noted that some operators have indicated their continued preference for segmentation or splitting both functions to maintain the benefits of maximizing faceplate densities, fault domain isolation, and decoupling technology roadmaps.
Service provider packet optical transport is the traditional market for coherent deployments. These predominantly use more versatile packet optical transport systems where advanced OTN/ Optical layer features (switching and cross connect), high density, and carrier-grade performance are required. Even here, CFP2- DCO provides full transponder functionality in a CFP2 form and doubles front plate densities compared to the CFP-DCO (and quadruples the line card capacity when 200G transmission is enabled).
Edge Aggregation, which includes service provider wireless backhauling, residential, and enterprise/data center aggregation applications
Links are defined as point-to-point single span or –ZR (for short) reaches between 40 km unamplified (loss limited case) and 80 km both unamplified and amplified (OSNR limited case).
Edge aggregation platforms are predominantly edge routers and L2/L3 switch-based mux-ponder nodes requiring low complexity and scalable 100/200G coherent uplink interfaces. The new digital coherent optics (DCO) in a CFP2 form factor (CFP2-DCO) perfectly suits such applications, adding true plug-and-play and pay-as-you-grow flexibility and enabling deployments to use integrated platforms (nowadays referred to as IP over DWDM or packet and optical layers in a single platform).
It should be noted that for the unamplified case (Figure 1), the user has possibility to trade off between single wavelength (i.e. without the AWG multiplexers) and multiple DWDM channel transmission. For the former, the AWG loss is “reallocated” to the fiber to enable much longer reach.
This 400G CFP2 muxponder provides a high-quality solution for solving transmission lines with insufficient fiber resources and high fiber line loss. It can realize the wavelength tunable of CFP2 coherent optical module and can be converted into DWDM standard wavelength optical signal. And it can be used to connected with DWDM multiplexer/demultiplexer to realize wavelength division multiplexing transmission. The 2x 400G CFP2 muxponder is designed in a 8x 100G service access module for optical fiber links.
- Support DWDM transmission wavelength conversion.
- The single card supports 8 channels 100G unidirectional or bidirectional service access.
- The line side supports 2 channels 400G CFP2 coherent optical modules
- Supporting multiple client-side service access: 100GBase-SR4/CWDM4/LR4/PSM4.
The 200G CFP2 Muxponder board supports 2x100G QSFP28 to 200G CFP2 electrical layer multiplexing / demultiplexing and is converted into a 200G rate WDM standard wavelength optical signal so that the multiplexing unit can deal with different wavelengths of light. The signal is wavelength-division multiplexed, and at the same time, the reverse of the above process is realized.
The CFP2 line side adopts advanced technologies such as DP-8QAM or DP-16QAM modulation and coherent reception, which overcomes the challenges of high-speed transmission systems for the physical effects of transmission such as OSNR requirements, CD tolerance, PMD tolerance, and non-linearity.
This CFP2 200G muxponder reach up to 800 kilometers without electric relay transmission, and supports C-band 96-wave (50GHz) tunables.