Google wants variable-rate Ethernet
On: 04/01/2013 Views: 64
When it comes to the fill-rate fraction/ratio of digital-domain Ethernet frames in the underlying analog-domain physical medium, a senior network architect at Google wants to have more flexibility regarding the denominator to push a link's typical fill-rate closer to 100%. The current scheme of inter-Ethernet-frame idle capacity as represented by a numerator that is notably smaller than the (currently-standardized fixed-size) denominator in the fill-rate is claimed to be unsuitable when interconnecting data-centers. The Institute of Electrical and Electronics Engineers Inc. (IEEE) isn't working on a variable-speed Ethernet standard yet, but Google is pushing for one.
It was a point of focus for Bikash Koley, Google's principal architect and manager of network architecture, during a panel session on the last day of OFC/NFOEC last week. What he wants is variable-speed Ethernet. So, instead of running a connection at 100 Gbit/s or 400 Gbit/s, which are the two standard choices, he'd like to pick arbitrary speeds. The technology on the optical side is actually ready for what he's asking. Variable-speed transceivers and flexible-grid ROADMs exist. What's missing is on the packet side: a media access control (MAC) layer that's capable of dealing with a variable-bit-rate physical (PHY) layer.