100G per Lambda Optics Paving Fast Path to 25Tbps Switches with 100G Electrical I/O

With increased demand for global network bandwidth, the hyper-scale cloud providers are in a position to consume the next generation of higher capacity, 100G SerDes enabled switches as soon as they can get their hands on them.  Cloud providers are already operating at extremely high rates of utilization and would welcome a higher performance, intelligent and more efficient intrastructure boost.  The key technology building blocks are in place to prototype 25.6Tbps switch based networks in 2H2019 and ramp in 2020.  This is a year or two ahead of popular thought.

Today’s ramp of 100G per lambda optics which is enabling 50G SerDes based 12.8Tbps switches in the form DR4/FR4 optical modules are laying the groundwork for a rapid transition to 25.6Tbps switches based on 100G SerDes technology.  To understand the rapid tranisional possibility it is important to look back at optics transistions from 10G to 100G.  The move to 25G SerDes enabled switches required the optics to move from 10G to 25G per lambda.  This transition was challenging and caused a two year delay in ramping 3.2Tbps switch enabled networks.  The next big move to 100G per lambda for the ramp of 12.8Tbps, 1RU switches requires a doubling in baud rate and modulation (PAM2 to PAM4).  As a result, optics again are the delay to mass deployment of the latest generation of 12.8Tbps switches “BUT” this strategic, aggressive move to 100G per lambda as a mainstream technology in 2019 creates the unique inflection point of “optics” leading the next generation switch silicon for the first time since god knows when.  Moving from in-module 50G to 100G gearboxes to 100G to 100G retimers to match the switch single-lane rate is generally recognized as straight forward.

Moving to 100G end-to-end connectivity.  As discussed, the fundamental 100G per lambda optical PMDs are in place.  In parallel, Credo has been publicly  demonstrating low power, high performance 100G single-lane electrical SerDes manufactured in mature 16nm technology since December 2017.  We as an industry simply need to agree on some common sense items such as VSR/C2M reach and 800G optical module specifications and execute on a few strategic silicon tape-outs in the 1H2019 to bring the 25.6Tbps into the light.

In my next Blog I will layout the fundational silicon steps to make 100G single-lane, end-to-end connectivity a mainstream reality in 2020. Stay tuned…

By Jeff Twombly, VP of Marketing and Business Development at Credo, @twoms63.