EUGENE PARK 800G MSA PLUGGABLES
KEY FEATURES NEEDED FOR 800G MSA PLUGGABLE MODULES To meet customer needs and drive future adoption, 800G coherent MSA pluggables should have a number of key features and capabilities including optical transmission, client traffic, low power consumption, and interoperable module management. Optical Transmission Features OIF 800ZR and high-performance interoperable PCS modes. With 400G, there was an interoperable standard performance of OIF’s 400ZR variant followed by OpenZR+ that provided higher performance capability and additional functionality. Similarly, OIF is defining an interoperable standard performance 800ZR variant addressing coherent line interfaces for amplified, single span, DWDM links over 80km using the Class 3 optics operating at ~4 bits per symbol (equivalent to 16QAM) modulation. For a higher performance 800G solution, Open ROADM is defining enhanced performance modes that include an interoperable probability constellation shaping (PCS) implementation utilising both Ethernet and OTN framing. Multi-haul capable. In current Class 2 ~60Gbaud MSA pluggable solution designs capable of adjusting the modulation mode, a long reach 200G capability is available by setting the modulation order to QPSK (2 bits per symbol) rather than 16QAM (4 bits per symbol) used for 400G transmission. This capability was standardised in Open ROADM and adopted by OpenZR+. Class 3 ~120Gbaud solutions can be used for 800G metro/regional reaches, and also for multiple different standard and proprietary modes at 400G and 600G to address a wide range of network requirements. High transmit optical power capability. Similar to high-Tx (>0dBm) optical power capabilities introduced in Acacia’s Bright 400ZR+ QSFP-DD modules, 800G coherent MSA modules will require optical amplification to operate over traditional brownfield networks with ROADM network elements. Internal optical amplification is a key feature variant for this generation to support these types of networks. Client Traffic Features 800GbE client traffic support. A key client traffic protocol to be supported in 800G generation coherent MSA pluggables is 800GbE. IEEE P802.3df™ aims to define the requirements for native Ethernet traffic at 800G data rates. To support native 800G Ethernet traffic from switch/router I/O ports, 800G generation coherent MSA
Interoperable PCS Modes Taking a page from the performance- optimised coherent playbook, 800G MSA pluggable solutions are expected to introduce interoperable PCS optical transmission. PCS shapes the optical transmission using an algorithm that weights the constellation to utilise the inner points more than the outer points, resulting in improved OSNR performance with a minimal increase in overhead. Previous implementations of PCS have always been proprietary, but this pluggable generation provides the industry’s first introduction of interoperable PCS.
pluggables are required to support this protocol.
Multiplexing lower speed 100/200/400GbE electrical client traffic. It is expected that when 800G coherent MSA pluggables are introduced, 100GbE, 200GbE, and 400GbE will continue to be widely deployed client traffic speeds. Therefore, 800G pluggables need to support the ability to multiplex these lower speed protocols into 800G transmission, with requirements being established by the standardisation groups.
Figure 2. High-level block diagram comparing 800G MSA pluggable solutions utilising 800ZR standard transmission and 800ZR+ interoperable PCS mode for higher OSNR performance.
Power Consumption and Management Low power consumption. As with other MSA pluggable solutions, optimising for low-power operation is a priority. The leveraging of Moore’s law with decreasing CMOS node sizes along with increased ASIC functionality has been a reason for the success of coherent pluggables—providing high-capacity links in a small form-factor. Power- optimised designs continue to be a priority for the new generation of Class 3 baud rate coherent MSA pluggables, not only for compliance in 800G slots, but also for backwards compatibility into lower-rate 400G legacy ports which have more restrictive power consumption requirements. Coherent Content Management Interoperability Services (C-CMIS) compliance. In addition to industry standardisation efforts at the optical transmission and client traffic levels, there has been a concerted effort to ensure multi-vendor interoperability of the module management interface through C-CMIS, which is defined in OIF. This ensures a common and predictable management signalling interface between the module and the host switch/router from one module vendor to another. C-CMIS compliance, a key requirement for 400G MSA modules, is going to extend to 800G as well.
Driven by Open ROADM, the 800G interoperable PCS implementation provides a power-optimised method to boost the performance of 800G MSA pluggables. This additional performance allows 800G implementations to achieve similar reaches as 400G implementations based on 16QAM transmission. This Open ROADM interoperable PCS mode operates in the 130+Gbaud range, which is slightly higher than the 800ZR mode, but can still enable transmission in 150GHz channels.
THE ROAD TO 800G PLUGGABLES CONTINUES
As discussed, the features below are key functional requirements that operators are looking for to transition to 800G coherent MSA pluggables. • Support for OIF 800ZR and high- performance interoperable PCS modes • Multi-haul capable • High Tx optical power option • 800GbE client traffic support • Multiplexing lower speed 100/200/400GbE electrical client traffic • Low power consumption • C-CMIS compliance This solution can plug directly into switch/ router ports to further drive adoption of IP- over-DWDM router-based optical network architectures. The first 800G pluggable deployments are expected in 2024.
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ISSUE 34 | Q3 2023
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