Standards Update: 200GbE, 400GbE and Beyond with Pete Anslow – “Live” from Geneva
By Helen Xenos, Pete Anslow – IEEE 802.3bs defines the technical specifications to support MAC or Ethernet data rates of 200Gb/s and 400Gb/s – double and four times the capacity of Ethernet rates today – that can operate at distances to meet the requirements for most applications. The objective of the project is to define specifications that will enable multi-vendor interop, using appropriate technologies that will meet the performance and cost points required by the industry. Cost will be a function of volume and yield of components, so we aim to use existing components and technologies that can be supplied by multiple vendors.
The IEEE 802.3bs project defines physical layer specifications for operation over 100m (400GBASE-SR16), 500m (200GBASE-DR4 and 400GBASE-DR4), 2km (200GBASE-FR4 and 400GBASE-FR8), and 10km (200GBASE-LR4 and 400GBASE-LR8) distances.
The most popular formats to meet the majority of core router to transport distance requirements are the 2km and 10km devices.
While the per lane technology for 100GbE used 25Gbps NRZ signaling, we are now using PAM4 signaling for most of the new electrical and optical interface specifications. PAM4 stands for Pulse Amplitude Modulation with the “4” indicating 4 levels of modulation. 50G PAM4 requires a more sophisticated receiver design but allows for the doubling of capacity per lane while reusing existing high volume, reliable electro-optics. The signal operates at a symbol rate of 25GBaud (speed of the electro-optics), but carries 2 bits per symbol, thus doubling the capacity (50G per lane). more>