Ethernet: The Definitive Guide, 2nd Edition

Chapter 12. 40 Gigabit Ethernet

The development of a new Ethernet system that operates faster than 10 Gb/s began with a Higher Speed Study Group “Call For Interest” meeting in July 2006. In response, an IEEE task force was formed to develop a 100 Gb/s Ethernet system in the 802.3ba supplement. This effort was then expanded to include 40 Gb/s Ethernet, and the combined 40 and 100 Gb/s 802.3ba supplement was completed and published in 2010. The 40 and 100 Gb/s specifications were adopted into the standard as Clauses 80 through 89.

It’s unusual for a new Ethernet media system to operate at a speed other than 10x faster than the previous standard. However, the 40 Gb/s speed was added to the 100 Gb/s standards effort to address a concern about the adoption rates for Ethernet technology. Early in the standardization process, a presentation was made to the 802.3ba task force to lobby for the addition of 40 Gb/s. The core of the argument was that while a 10x evolution in speed had worked well for the older 10 Mb/s, 100 Mb/s, and 1 Gb/s Ethernet systems, the data showed that the adoption rate for the 10 Gb/s system had been much slower than for previous systems.

The major reason given for the slower adoption rate was that servers had not been able to support the 10 Gb/s speed for several years after the standard was first developed, leaving only a relatively low-volume market of switch-to-switch interconnections for vendors to sell into. When it came to developing a new 100 Gb/s Ethernet standard, ...