Issue link: http://www.epageflip.net/i/1043933
26 I ICT TODAY The multimode standards are all based on 50GBASE-SR, a 50 Gb/s PAM-4 lane that can support up to 100 m on both OM4 and OM5 fiber. Since the 802.3cd PMDs operate only at 850 nm, there is no advantage to the multi-wavelength support offered by OM5 fiber. 100GBASE-SR2 is a two-pair solution, while 200G BASE-SR4 is a four-pair solution for 200 Gb/s. The latest IEEE task force to be formed is IEEE 802.3cm. This group has approval to develop two new 400 Gb/s multimode standards. The first PMD, 400GBASE-SR8, will use eight pairs of multimode fiber, each pair carrying 50 Gb/s. This was driven by a hyperscale customer who wanted the flexibility this solution offered, including breakout of 50, 100, and 200 Gb/s, as well as 400 Gb/s switch-to-switch links. There will be two different media interfaces for 400GBASE-SR8: the new 16-fiber MPO that was recently standardized in TIA and the older 24-fiber MPO connector that has two rows of 12 fibers. The second PMD is 400GBASE4.2. This will be the first standards-based application that will exhibit the reach advantage of wideband OM5 fiber. The task force has established several important parameters, including that the second wavelength (910 nm) and transmission will be bi-directional (BiDi). 400GBASE-SR4.2 plans to introduce a new naming scheme to clearly define the lanes used in the PMD: SRx.y, in which "x" indicates the number of fibers and "y" is the number of wavelengths. Conclusion Bandwidth demands in all parts of the enterprise continue to grow and application speeds are increasing to support those needs. Enterprise cloud, hybrid and hyperscale data centers will continue to deploy multimode optical fiber links, and multimode transceivers are evolving to support higher speed links needed in the newest data centers, including the hyperscale market. Multimode links continue to have cost and operation- al advantages over competing media types. Through the standards organizations and groups, such as the SWDM Multi-Source Agreement, the industry continues to develop new technological solutions to meet this explosive market demand. AUTHOR BIOGRAPHY: John Kamino, RCDD, is a senior manager of multimode optical fiber product management for OFS. His background includes product management, offer management, sales, and engineering. John has published numerous articles in technical publications and presented at multiple technical conferences. He participates in TIA and IEEE standards activities. He holds a BS degree in Chemical Engineering from the University of Nebraska-Lincoln, and an MBA from Mercer University. He can be reached at jkamino@ofsoptics.com. REFERENCES 1. In Support of 200G MMF Ethernet PMDs, NGMMF Study Group, January 2018. 2. Relative Link Costs for 100G Applications, NGMMF Study Group, January 2018. PMD Link Distance Fiber Count (f) and Media Type Technology 50GBASE-SR 100 m OM4/OM5 2-f multimode 1x50G PAM-4 850 nm 50GBASE-FR 2 km 2-f singlemode 1x50G PAM-4 1300 nm 50GBASE-LR 10 km 2-f singlemode 1x50G PAM-4 1300 nm 100GBASE-SR2 100 km 4-f multimode 2x50G PAM-4 850 nm 100GBASE-DR 500 km 2-f singlemode 1x100G PAM-4 1300 nm 200GBASE-SR4 100 km 8-f multimode 4x50G parallel PAM-4 850 nm TABLE 4: Standards under development for 50/100/200 Gb/s Ethernet (IEEE 802.3cd). What's Ahead for Ethernet? Table 4 highlights Ethernet standards under development for multimode fiber. IEEE802.3cd is working on a 50/100/200 Gb/s standard, which is expected to be published in the second half of 2018. Active – Publication expected in 2018