Monday, April 6, 2020

Ethernet Technology Consortium focuses on 800G

The 25 Gigabit Ethernet Consortium, originally established to develop 25, 50 and 100 Gbps Ethernet specifications, has changed its name to the Ethernet Technology Consortium in order to reflect a new focus on higher-speed Ethernet technologies, the 800GBASE-R specification for 800 Gigabit Ethernet (GbE).

The 800 GbE specification introduces a new media access control (MAC) and Physical Coding Sublayer (PCS). It essentially re-purposes two sets of the existing 400GbE logic from the IEEE 802.3bs standard with a few modifications in order to distribute the data across eight 106 Gb/s physical lanes. As the PCS is reused, the standard RS(544, 514) forward error correction is retained, for simple compatibility with existing physical layer specifications.

The Ethernet Technology Consortium said its goal is to enhance the Ethernet specification to operate at new speeds by utilizing specifications that are developed or in development. This allows the organization to work alongside other industry groups and standards bodies to adapt Ethernet at a pace that aligns with the rapidly evolving needs of the industry. The ETC has more than 45 members with top-level promoter members that include Arista, Broadcom, Cisco, Dell, Google, Mellanox and Microsoft.


“Ethernet is evolving very quickly and as a group, we felt that having 25G in the name was too constraining for the scope of the consortium,” said Brad Booth, chair of the Ethernet Technology Consortium. “We wanted to open that up so that the industry could have an organization that could enhance Ethernet specifications for new and developing markets.”

“The intent with this work was to repurpose the standard 400GbE logic as much as possible to create an 800 GbE MAC and PCS specification with minimal overhead cost to users implementing multi-rate Ethernet ports,” said Rob Stone, technical working group chair of the Ethernet Technology Consortium. “The 800 GbE specification is an exciting first announcement under the consortium’s new name, reflecting the true capability of the organization. We are proud of the hard work of our member companies in completing this specification.”

https://ethernettechnologyconsortium.org

Low latency spec for 50GbE tweaks forward error correction

The 25 Gigabit Ethernet Consortium has completed a low-latency forward error correction (FEC) specification for 50 Gbps, 100 Gbps and 200 Gbps Ethernet networks.

The new spec cuts FEC latency approximately in half by using a shortened codeword FEC variant – RS (272, 257+1, 7, 10) that replaces the IEEE 802.3cd and 802.3bs standard FEC.  The shortened codeword contains 272 x 10-bit symbols rather than the 544 x 10-bit symbols originally specified. Nothing else changes in the symbol distribution process from the output of the encoder to the FEC lanes in the new FEC, but that process is implemented more quickly due to the shortened codeword.

This will have a significant impact on overall physical layer latency, in particular for hyperscale datacenter networks comprised of a large number of nodes, with multiple hops between servers.

“Five years ago, only HPC developers cared about low latency, but today has latency sensitivity has come to many more mainstream applications,” said Rob Stone, technical working group chair of the 25G Ethernet Consortium. “With this new specification, the consortium is improving the single largest source of packet processing latency, which improves the performance that high-speed Ethernet brings to these applications.”

The specification is available at https://25gethernet.org/ll-fec-specification

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