New COBO Specifications Prepare Industry for the Higher Speeds Ahead

By Amy Goetzman | May 07, 2018

The Consortium for On-Board Optics (COBO) has released the industry’s first on-board optics specification. What does this mean for you?

In April 2018, the Consortium for On-Board Optics (COBO) released its first specification for optics that reside on the motherboard. COBO has specified modules capable of 400G and 800G rates. The designs will also support 800G and 1.6TbE rates with the advent of 100G single-lane electrical signals.

Brad Booth, COBO

COBO President Brad Booth

The group formed in 2015 to develop interoperable specifications to lower power consumption and increase bandwidth for optics in the next generation of enterprise and data centers. COBO includes members from across the electronics industry and from connector companies including Samtec, TE Connectivity, US Conec, Sumitomo, Yamaichi, HUBER+SUHNER, Molex, and Amphenol. We talked to COBO President Brad Booth about the new specification and how it will influence future systems.

Connector Supplier: What advantages will a common specification for on-board optics provide?

Brad Booth: A common specification permits multi-vendor interoperability and supply. Proprietary on-board optics lack those elements, which was one of the biggest issues for companies using those solutions.

CS: What factors made now the right time to address these issues?

Booth: At the start of COBO, there were no faceplate pluggable module specifications that the industry wanted to use in their data center switches. While many knew the industry would solve this issue for 400G Ethernet, there was a realization that beyond 400G, the ability to continue to use faceplate pluggable optics would get more difficult due to signal integrity and increased thermal load. The founding members felt it would be better to create a solution while the industry still has alternatives rather than waiting until the last minute. On-board optic modules change the operating model; therefore, the industry needs to learn the pros and cons with these solutions now to enable further refinement and improvement for when the transition to on-board optics is necessary.

CB: How will data center design be impacted by the new COBO specifications?

Booth: The design of the data center will remain the same, but the operation of the data center will be impacted. COBO enables modules to be populated on switches and shipped to the data center fully tested and ready to go. The failure of a module has a different means of replacement than a faceplate pluggable, but COBO members enabled the ability for the industry to remove and replace a failed module. Only by building and using switches populated with on-board optics will the industry come to understand the true impact of data center design and operation.

CS: What other products will be impacted?

Booth: While COBO targeted a 1RU switch as its perceived worst-case environment, COBO is not limited to that market. It can be used on switches, routers, servers, transponders, etc. Any place that someone uses optical interfaces, COBO can be used.

CS: Two main connectors are used in the COBO design: One high-speed and one low-speed. What role does each of those connectors play in the design?

Booth: The COBO connectors serve multiple functions. The high-speed connector supplies the data interface while also serving as a landing spot for the module before it is inserted. The low-speed connector is the power, ground, and management interface for the module and helps align the module as it is lowered onto the connectors. Once the module is seated in the connectors, either connector can be used to latch and hold the module in place. The module is held in place by both connectors, giving it greater stability once seated.

CS: Are there currently connectors available that meet these requirements or will this standard inspire new products?

Booth: These connectors were created based upon merging two designs already in use in the industry. COBO exists to help its members and the industry improve and enhance the current design to either enable new markets or improve the overall design.

CS: How did connector companies work with the COBO group to help develop the specification?

Booth: Connector companies provided COBO members with a vast quantity of information on the performance and design of their connectors. The COBO members were able to use the data provided to perform signal integrity simulations, thermal modeling, optical connectivity studies, and more in the development of the existing specification.

CS: What challenges does the COBO group face in bringing the specification into widespread acceptance or use?

Booth: Time. It’s very easy to continue to use the same tools over and over, but very difficult to pick up and starting using a new tool. While there is a vast quantity of industry knowledge on the use of on-board or embedded optics, the access to an industry specification that supports such a broad range of technologies and applications is new. COBO has added on-board optics to the tool kit of what companies can use to develop optical interfaces, and with time and experience, the ability to use that tool will help the industry when the other tools may not suffice.

CS: At what point, in terms of speed and other factors, will new guidance be needed?

Booth: COBO’s publication of Release 1.0 of the x8 and x16 on-board optical module specification supports up to 28Gbaud electrical interfaces for modules that drive multimode and single-mode fiber. With three lengths (using the same connector footprint), COBO has created a specification that enables multiple power and thermal classes. COBO is already planning to release application notes on using the module for coherent optical modules, guidance on optical connectivity, and information on PCB material and thermal evaluations. The members are also discussing the high-speed electrical interface being able to support 56Gbaud, which would permit the x16 module to be capable of supporting 1.6Tb/s of bandwidth. That work is expected to commence once the standards bodies (OIF and IEEE 802.3) have made sufficient progress on their 56Gbaud specifications.

Visit COBO online to learn more about the working groups and the new specifications.

Amy Goetzman
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