Members of the IEEE at their January 2016 meeting agreed to objectives for 200 Gigabit Ethernet PMDs. They also decided to vote on a proposal to tie specification work to reach these objectives to a pair of other initiatives: 400 Gigabit Ethernet and a new 50 Gigabit Ethernet effort.
Final approvals of how to address the new standardization efforts related to 50 and 200 Gigabit Ethernet are pending, with final approval anticipated in May.
According to John D'Ambrosia, chairman of the Ethernet Alliance and senior principal engineer, IP standards, at Huawei Technologies Co. Ltd., the specification effort will build on current work within the IEEE to specify 50-Gbps electrical and optical lanes. That's why responsibility for the single-mode specifications likely will fall to the IEEE P802.3bs Task Force on 400 Gigabit Ethernet (400GbE). A vote will soon be held to make the multimode specifications part of a new task force that will also tackle 50 Gigabit Ethernet. That task force could be called P802.3cd, D'Ambrosia said.
It is anticipated that the 400 Gigabit Ethernet group will now be charged with developing specifications for 2 km and 10 km applications of 200 Gigabit Ethernet. It is expected that each PMD will leverage four optical lanes of 50 Gbps each; an electrical interface, called CCAUI, will also be specified. D'Ambrosia says given the adoption of PAM-4 for electrical interfaces in the 400GbE project that PAM-4 will most likely serve as the modulation format.
D'Ambrosia added that a PSM4-like approach for 500 m over single-mode fiber is also being considered. Developing a specification based on two 100-Gbps lanes, leveraging the short-reach 4x100G PMD also part of the 400GbE specification set (see "IEEE P802.3bs Task Force adopts serial 100G for 400 Gigabit Ethernet"), is currently not on the table, he added.
On the multimode side, the anticipated new task force will be entering uncharted territory when it comes to 200 Gbps, D'Ambrosia points out. The multimode version of 400GbE is based on 25-Gbps electrical and optical lanes, so pushing 50 Gbps across multimode fiber represents a new task. D'Ambrosia noted the task force will target 100 m reach, likely using some sort of forward error correction (FEC).
At 50 Gbps, the new task force will address backplane, twinax copper cable, multimode fiber, and 2-km and 10-km single-mode fiber applications, and also apply this 50 Gbps electrical signaling over 2 lanes to target 100 Gigabit Ethernet over backplanes, copper cables, and 100 m of multimode fiber, D'Ambrosia reports. Its work should begin this May.
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