Terabit BiDi MSA Overview: A Beginner Guide

40G BiDi, 100G BiDi, and 400G BiDi transceivers are gaining popularity for multimode data center applications. Responding to future data center bandwidth expansion needs, some industry leaders, including II-VI, Alibaba, Arista Networks, Broadcom, and Cisco, have formed Terabit BiDi MSA in February 2022 to define and promote an open standard for next-generation Terabit Ethernet over multimode fiber cabling. This post will provide an overview of Terabit BiDi MSA, including its backgounds, advantages, and FAQ, hope it is helpful for the begginer.

Table of Contents

Background of Terabit BiDi MSA
Terabit BiDi MSA Overview
Advantage of Terabit BiDi Technology
FAQ about Terabit BiDi
Final Words

Background of Terabit BiDi MSA

Around 2014, the first 40G BiDi transceivers for commercial deployment in multimode data center applications hit the market. Using the 2x20G NRZ wavelength channels in each direction, these 40G BiDi transceivers could achieve a total data rate of 40Gbps over two strands of standard OM3 or OM4 fiber. This was a very attractive proposition for data center operators because it enabled them to upgrade their cabling infrastructure to support much higher bandwidth while still using the same fiber type and cable plant.

In the years that followed, 100G BiDi transceivers were developed and made available for commercial deployment. These 100G BiDi transceivers use 2x50G PAM4 signal channels in each direction to achieve a data rate of 100Gbps over two strands of standard OM4 or OM5 fiber. The development of 100G BiDi transceivers was a significant milestone because it enabled data center operators to upgrade their cabling infrastructure to support even higher Ethernet bandwidth.

In 2018, 400G BiDi MSA released an initial version of 400G-BD4.2 Specification. Then in 2019, Terabit BiDi MSA was established to define a next-generation Terabit Ethernet over multimode fiber cabling standard. Terabit BiDi MSA leverages learnings and innovations from 40G BiDi, 100G BiDi, and 400G BiDi to enable Terabit Ethernet over 8 or 16 strands of standard OM4/OM5 fiber.

The below tables list the comparison for 40G BiDi vs. 100G BiDi vs. 400G BiDi vs. Terabit BiDi

Compare	40G BiDi	100G BiDi	400G BiDi	Terabit BiDi
Media Type	OM3, OM4, OM5	OM3, OM4, OM5	OM3, OM4, OM5	OM4, OM5
Reach	100m@OM3 150m@OM4	100m@OM4 150m@OM5	100m@OM4 150m@OM5	TBD
Fiber Connector	LC Duplex	LC Duplex	MPO/MTP-8	MPO/MTP-8 MPO/MTP-16
Modulation Format	NRZ	PAM4	PAM4	PAM4
Wavelength	850nm/910nm	850nm/910nm	850nm/910nm	850nm/910nm
Fiber Count	2 Fiber	2 Fiber	8 Fiber	8 or 16 Fiber

40G BiDi vs. 100G BiDi vs. 400G BiDi vs. Terabit BiDi Comparison

Terabit BiDi MSA Overview

Terabit BiDi MSA was founded in February 2019 by founding members II-VI, Alibaba, Arista Networks, Broadcom, Cisco, CommScope, Dell Technologies, HGGenuine, Lumentum, MACOM, and Marvell Technology. Terabit BiDi MSA is an open consortium comprised of leading operators, optical transceivers, switches, and cable suppliers.

Terabit BiDi MSA’s objective is to define an open standard for Terabit Ethernet over multimode fiber cabling based on learnings and innovations from 40G BiDi, 100G BiDi, and 400G BiDi. Terabit BiDi MSA’s ultimate goal is to enable data center operators to upgrade their cabling infrastructure to support Terabit Ethernet with unprecedented simplicity and low cost.

The Terabit BiDi MSA group has not yet released detailed specifications. We expect to be able to soon share more information with you as it becomes available. Terabit BiDi MSA is an open consortium, and you can submit your company information to join Terabit BiDi MSA.

Advantage of Terabit BiDi Technology

#1: Optimize existing fiber cabling

Terabit BiDi MSA enables 800G or 1.6T Ethernet over existing OM4 or OM5 fiber, the most commonly deployed type of multimode fiber cabling in data centers today. Terabit BiDi reduces the cabling and infrastructure needed to support high-speed Ethernet applications, which can simplify data center deployments and operations. Terabit BiDi MSA also provides a clear upgrade path from existing 400G Ethernet deployments.

#2: Low cost and Low Complexity

Terabit BiDi MSA supports 800G or 1.6T Ethernet over low-cost multimode fiber, using a low-cost and low-complexity optical interface. Without deploying new fiber, Terabit BiDi MSA helps data center operators to achieve the next level of high-speed Ethernet performance while minimizing cabling and infrastructure costs.

#3: High Port Density

Terabit BiDi MSA supports up to 800G or 1.6T Ethernet in a single optics, enabling data center operators to achieve high port density and high bandwidth in their data center deployments.

FAQ about Terabit BiDi

Q: Is the Terabit BiDi MSA reliant on other standards activities?
A: The Terabit BiDi MSA will encourage interface solutions based on multi-mode 100 Gb/s per optical lane technologies and architectures for use at 800 Gb/s and 1.6 Tb/s, with various examples already specified or in development in IEEE 802.3 or by other MSAs. The Terabit BiDi MSA will also draw on and refer to form-factor-specific MSAs like the QSFP28, OSFP, QSFP-DD, and OSFP-XD MSAs, as well as the common module Interface Specification, when needed (CMIS).

Q: Will this comply with the forthcoming Ethernet requirements of 800 Gb/s and 1.6 Tb/s?
A: It will build on basic Ethernet specifications (including PCS).

Q: What is the difference between 100G BiDi, 400G BiDi, and Terabit BiDi?
A: First difference is the bandwidth. 100G BiDi supports 100 Gbps over two standard OM3, OM4, or OM5 fiber strands. 400G BiDi supports 400 Gbps over eight standard OM4 or OM5 fiber strands. Terabit BiDi supports 800 Gbps over eight standard OM4 or OM5 strands or 1.6 Tbps over Sixteen standard OM4 or OM5 fiber strands.

The second difference is the connector type. 100G BiDi transceiver usually uses LC duplex connectors, 400G BiDi transceiver uses MPO/MTP-8 connectors. Terabit BiDi MSA is still under discussion, and no agreement has been reached on the connector type.

Q: What is the Terabit BiDi technology application?
A: Terabit BiDi is mainly used in crucial high-volume connectivity between switches and server-switch interconnects in contemporary data centers.

Final Words

We hope this post has given you a basic understanding of Terabit BiDi MSA. Terabit BiDi MSA’s goal is to enable data center operators to upgrade their cabling infrastructure to support Terabit Ethernet with unprecedented simplicity and low cost. The Terabit BiDi MSA is an exciting development in the world of high-speed Ethernet, and we are looking forward to seeing how it unfolds. Stay tuned for more updates as they become available!

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Terabit BiDi MSA

Optical Transceiver