January 4, 2018
Author Stephen Hardy
Editorial Director and Associate Publisher
The Ethernet Alliance says it's ready to help move the newly approved standards for 200 Gigabit Ethernet and 400 Gigabit Ethernet into commercial deployment. The new specifications, under IEEE 802.3bs, "Standard for Ethernet Amendment: Media Access Control Parameters, Physical Layers, and Management Parameters for 200 gigabit per second (Gb/s) and 400 Gb/s Operation," achieved full ratification December 6, 2017.
"IEEE 802.3bs represents a transformational moment in the move to next generation of networks. The delivery of 200G and 400G is arriving just in time to meet growing needs for reliable, high-speed connectivity from a diverse array of applications and markets," said John D'Ambrosia, chairman of the Ethernet Alliance, senior principal engineer at Huawei, and chairman of the IEEE P802.3bs Task Force (see "The journey to 400 Gigabit Ethernet"). "The exceptional effort resulting in the completion of this standard is only the start of the industry's investment in the networks of tomorrow. We've laid a firm foundation for 200G and 400G with our early interoperability demonstrations and plugfests, but it's time to kick things into high gear. The real work of testing and verifying multivendor interoperability begins now, and the Ethernet Alliance is ready. We look forward to building on past successes and helping accelerate 200G and 400G Ethernet's rollout and adoption."
The Task Force began its work in 2014 with only 400 Gigabit Ethernet on its plate. The group tackled both multimode and single-mode scenarios, with the single-mode specifications using PAM4 modulation. The specifications include:
-400GBASE-SR16, which covers at least 100 m over multimode fiber via 16 transmit and another 16 receive fibers, each transmitting at 25 Gbps (a study group has formed to investigate whether OM5 fiber and shortwave WDM technology could lessen the number of fibers required)
-400GBASE-DR4, for at least 500 m over single-mode fiber using four parallel fibers in each direction with 100-Gbps transmission on each fiber; the decision to target 100-Gbps transmission was the subject of spirited debate (see "IEEE P802.3bs Task Force adopts serial 100G for 400 Gigabit Ethernet")
-400GBASE-FR8, which uses eight-wavelength WDM to treat reaches of at least 2 km over a single-mode fiber in each direction
-400GBASE-LR8, which is similar with -FR8 except the reach is extended to at least 10 km over single-mode fiber.
These optical specifications are supported by a pair of electrical interfaces, the 8-lane 400GAUI-8 and the 16-lane 400GAUI-16.
Completion of the Task Force's work was delayed somewhat when it was also given responsibility for drafting the single-mode fiber specifications for 200 Gigabit Ethernet in 2016 (see "IEEE sets objectives for 200 Gigabit Ethernet"; the multimode fiber specifications are the responsibility of the IEEE P802.3cd Task Force, as described in "IEEE approves standards initiatives for 25 Gigabit Ethernet, 50, Gigabit Ethernet, 200 Gigabit Ethernet"). The rationale was that single-mode 200 Gigabit Ethernet could be based on variants of the 400 Gigabit Ethernet specifications. And so it is, particularly in the use of PAM4-enabled 50-Gbps transmission. The specifications include:
-200GBASE-DR4 for at least 500 m via four parallel fibers in each direction
-200GBASE-FR4 for at least 2 km via four-wavelength CWDM in each direction
-200GBASE-LR4 for at least 10 km via four wavelengths in each direction
The complementary electrical interfaces similarly are "half" of their 400 Gigabit Ethernet counterparts, four-lane 200GAUI-4 and eight-lane 200GAUI-8.
With the specifications formally in place, the Ethernet Alliance hopes to build on its previous work to help smooth the technologies' path to market. The group held a 400 Gigabit Ethernet demonstration at OFC 2017 in Los Angeles and suggests it will host interoperability tests and further demonstrations in the future.