The effort to create specifications for 400 Gigabit Ethernet (400GbE) has reached a major milestone with the formal creation of the IEEE P802.3bs Task Force. John D’Ambrosia, chair of the 400GbE Study Group within the IEEE as well as chair of the Ethernet Alliance, was named acting chair of the Task Force.
As noted by Stephen Hardy at cablinginstall.com's sister site Lightwave, D’Ambrosia, who should be formally installed as Task Force chairman at the IEEE 802.3/IEEE 802.1 Joint Interim Meeting in Norfolk, VA, the week of May 12, 2014, faces a very full plate of decisions and issues that must be cleared in the path toward a ratified standard.
The Task Force will tackle Ethernet Media Access Control (MAC) parameters, physical layer specifications, and management parameters for Ethernet transmission at 400 Gbps. This will include the creation of Physical Medium Dependent Sublayers (PMDs) for such applications as 100 m over multimode fiber and 500 m, 2 km, and 10 km via singlemode fiber.
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D’Ambrosia noted that several technological issues will need to be straightened out to achieve these goals. According to Lightwave's Hardy, among the most salient are:
-- Sorting among approaches based on the use of multiple wavelengths, multiple fibers, and/or such modulation formats as discrete multi-tone (DMT) and pulse-amplitude modulation (PAM) for each PMD.
-- Establishing an architecture framework that will support interoperability among what D’Ambrosia expects will be multiple generations of 400GbE. For example, the creation of an approach using 16 lanes of 25 Gbps can be expected, but D’Ambrosia predicts that there will be interest in establishing specifications for 8x50-Gbps and 4x100-Gbps flavors as well. If one looks at a technology such as forward error correction (FEC), how should the use of FEC be specified, possibly for both the electrical lanes as well as the optical ones, to minimize incompatibilities among the different generations?
-- Developing the necessary electrical interfaces for chip-to-chip and chip-to-module communications.
See also: Cabling infrastructure developers avow 400G union
"It’s too early to predict how all of this will sort out," writes Hardy. "But D’Ambrosia said he expects the multimode PMD will use a parallel fiber approach. A parallel approach also may be appealing for the 500-m singlemode PMD, particularly to support 100GbE breakouts. However, D’Ambrosia believes that, based on reaction to the IEEE 802.3bm 40 and 100 Gigabit Ethernet specifications, users prefer single-fiber approaches to longer-reach applications such as 2 and 10 km."
Full story:400 Gigabit Ethernet Task Force ready to get to work (lightwaveonline.com)
