Yeah, I know, 800G isn’t really ‘new’, it’s been around since 2020 so why am I writing about this now in 2024? Well, this isn’t your father’s 800G, it’s new and improved compared to those first-to-market solutions with better performance for enhanced support of multiple transport applications.
The 2020 version of 800G was based on what market research firm Cignal AI categorizes as Gen90P, electronics (DSPs) and optics operating at a minimum 90 Gbaud symbol rates that, while providing a higher bit rate channel, are somewhat limited in terms of delivering performance. Many of the ‘hero experiments’ and lab trials that were announced at the time touted distances up to 1000Km for the full line rate which sounds impressive but in real-world networks settled in to the 200-300Km range which is still good, but doesn’t quite meet the requirement of larger metro and regional networks.
Today we are moving into the Gen120P era in which symbol rates are a minimum 120Gbaud per channel but more typically run at 135-145 Gbaud to squeeze out extra performance while accommodating the faster 1.2 Tbps bit line rate. As with all previous generations, this new generation of technology will be available in high-performance transponders first before it is productized into smaller, pluggable form factors with more limited performance.
What’s different about Gen120P is that, unlike previous coherent generations, the headline rate is not the primary feature that service providers are after. What they really want to do is push the 800G and 400G line rates they have now, farther. The enhanced performance that the wider channel width provides for the now sub-rate 800G and 400G wavelengths means they can go longer distances than they can at 90 Gbaud before the OSNR threshold is reached. While the full 1.2T will be used by some hyperscale data center operators for shorter reach point-to-point links, 800G and 400G will remain the preferred line rates for a vast majority of operators because they align perfectly with the dominant 400GbE and newer 800GbE client optics making it easier to aggregate and transport their traffic on their transponders.
They also have the reach they need to close regional and long haul links they couldn’t with Gen90P. At 120+ Gbaud, a 400G wavelength can now travel thousands of kilometers making it useful for long haul networks replacing 100G and 200G spans, while 800G extends hundreds of kilometers moving it from being a pure DCI play to a true metro-regional solution replacing 400G. The effect this has is to double the bandwidth available for these applications. With this kind of performance, it expands the addressable market considerably for 800G, tripling it between 2022 and 2024 in terms of number of ports shipped. And this market will be addressed with Gen 120P optics that will grow at more than five times the rate as Gen90P now that the have become generally available in the market.
So what’s old (if you consider 2020 old) is new again, this time with better performance. While Gen90P was a fine as an interim solution at 800G, the real action starts now with a fully functional solution that can address all the applications with the line rates that service providers really want.
