What will the 400G BiDi MSA group define?
The MSA group is dedicated to defining optical data link specifications based on a dual wavelength bidirectional transmission technology on multimode fiber (MMF) that enables a reduction in fiber count relative to other solutions. The 400 Gbps BiDi solution leverages both the widely adopted 40 Gbps and 100 Gbps BiDi solutions for Ethernet applications and is compatible with the widely available and deployed parallel multimode optical fiber cabling infrastructure.
The 400G BiDi MSA group will define optical specifications for transmitting 400 Gbps Ethernet traffic over “4+4” MPO connectorized multimode optical fiber (OM3, OM4 and OM5) – consistent with the optical fiber and connector currently used for 40GBASE-SR4 and 100GBASE-SR4. This enables a migration path for existing fiber infrastructure towards higher speeds. This optical interface is capable of being implemented in various form factor types, such as QSFP-DD and OSFP.
Multimode Link Distance 400G BiDi MSA
- OM3 MMF operating range: 0.5m ~ 70m
- OM4 MMF operating range: 0.5m ~ 100m
- OM5 MMF operating range: 0.5m ~ 150m
What are the key features of 400G BiDi solutions?
Optical bidirectional technology allows each single fiber to carry signals in both directions, thereby improving fiber utilization relative to existing 400G MMF standards. For a 100G BiDi link, one fiber pair is required (consistent with commonly installed infrastructure such as a duplex LC) running 53.125 Gbps on each fiber in both directions for an aggregate of 106.25 Gbps. The 400G BiDi specification is a quad version of the 100G BiDi approach utilizing four fiber pairs (consistent with commonly installed infrastructure such as a 4+4 fiber MPO). For all BiDi implementations, only one laser is launched into each fiber end, simplifying optical design and keeping costs low.
Why does the industry need another 400 Gbps optical specification?
The successful industry adoption of MMF BiDi technology is based on its ability to support the commonly installed fiber infrastructure at new, higher speeds. While there is a robust series of 400G optical interfaces being specified for single mode fiber solutions, the only 400 GbE multimode standard that has been defined by the IEEE is 400GBASE-SR16 (Clause 123 of IEEE Std 802.3-2018) using 16+16 optical fiber. The IEEE has begun standardization of 400GBASE-SR8 (expected to be an amendment to Clause 138 of P802.3cd) using 8+8 optical fiber, but this solution is not compatible with existing and commonly deployed 4+4 optical fiber infrastructure (such as used with 100GBASE-SR4 and 40GBASE-SR4). The 400G BiDi specification provides a solution for 4+4 optical fiber.
What does the 400G BiDi specification define?
The 400G BiDi specification defines the 50 Gbps per lane PAM-4 optical signaling, modulation encoding, lane assignments and link characteristics for 400 Gbps MMF Ethernet applications. It does not define a physical form factor, FEC or electrical interface.
What is the name of the new specification?
The specification will be named 400G-BD4.2, to identify the bidirectional use of four lasers each of two colors. Using the 400G-BD4.2 specification, two transceivers communicate over lengths up to 70 meters (OM3), 100m (OM4) and 150m (OM5).
Is 400G BiDi compatible with prior 100G BiDi solutions in the industry?
Yes, the 400G-BD4.2 8x50G bidirectional MMF optical specifications are, in 2x50G pairs, compatible with 100G BiDi QSFP28 solutions in the industry.
Source from: https://www.400gbidi-msa.org/
