The international Standards body that specifies the requirements for today’s optical data communications for Data Center and Enterprise applications is the International Electronic & Electrical Engineers, i.e., the IEEE. The specified protocol for point-to-point or point-to-multipoint communications is “Ethernet.” The name Ethernet comes from the ancient Greek word, Ether, meaning the air that fills the cosmos that the God’s breath.
The Working Group under the IEEE that specifies Ethernet is 802.3. Each time a new higher speed Standard is developed, the IEEE assigns a project number for the new Clause by appending letters to the 802.3 Working Group designation. For example, “ae” was appended to 802.3 to form 802.3ae, which was the 10 Gb/s Ethernet Standard (Clause 52). Once the IEEE approves the project, a Task Force is formed and the Standard is development.
On June 2, 2020, the next higher speed Ethernet project was approved, P802.3db, “100 Gb/s, 200 Gb/s, and 400 Gb/s Operation over Optical Fiber using 100 Gb/s Signaling.” The Standard represents the next step in transmission bit rate, which is 100 Gb/s per duplex fiber pair. Each higher data rate is achieved by defining communications over one or more duplex pairs of a “BASE” band data rate. For example, 40 Gb/s was achieved by aggregating 4 duplex pairs of the baseband data rate of 10 Gb/s. Each of the four 10 Gb/s fiber pair can be used independently (breakout) or collectively for 40 Gb/s.
The baseband data rates defined by 802.3 includes; 10 Mb/s, 100 Mb/s (Fast Ethernet), 1 Gb/s, 10 Gb/s, 25 Gb/s, and 50 Gb/s. The newly approved Task Force 802.3db, will define the requirements for the next base rate of 100 Gb/s over a single duplex pair. Combining two parallel duplex fiber pairs enables 200 Gb/s, and 4 pairs enables an aggregate data rate of 400 Gb/s. The IEEE nomenclature for these three Standards will be 100GBASE-SR, 200GBASE-SR2, and 400GBASE-SR4, where S = Short Wavelength, R = 64/66 bit encoding, and the postscript number defines the number of duplex fiber pairs. The absences of a number implies only one duplex fiber pair.
Panduit is recommending to change the reach objective for this new 100 Gb/s baseband Standard from 50 m to at least 70 m, which will support 40% more channels in the data center, thereby extending the use of multimode fiber.
The contested parameter for 802.3db is the maximum channel reach objective. At the time the Project Authorization Request (PAR) was submitted for approval, the reach objective was 50 m. However, this channel reach is neither the maximum achievable channel reach, nor the lowest cost transceiver we can specify.
Members of Panduit’s Fiber Research & Development team have been active participants in the development of EEE 803.2 Standards since 2003, and we are currently contributing measured channel performance and modeling data to 802.3db in order to demonstrate feasibility of longer reach. Panduit is recommending to change the reach objective for this new 100 Gb/s baseband Standard from 50 m to at least 70 m, which will support 40% more channels in the data center, thereby extending the use of multimode fiber. The advantage of multimode channels is a lower cost option compared to single-mode channels.
In addition, Panduit will be supporting a proposal for a second solution for a shorter reach objective of only 20 m over OM3 fiber (30 m over OM4) to address the switch-to-server application. A 20 m reach will result in the lowest cost transceivers providing the user with a more economical option to utilize structured cabling in place of Active Optical Cables (AOC).