COBO targets year-end to complete specification

Part 3: 400-gigabit on-board optics

• COBO will support 400-gigabit and 800-gigabit interfaces 
• Three classes of module have been defined, the largest supporting at least 17.5W 

The Consortium for On-board Optics (COBO) is scheduled to complete its module specification this year.

A draft specification defining the mechanical aspects of the embedded optics - the dimensions, connector and electrical interface - is already being reviewed by the consortium’s members.

Brad Booth“The draft specification encompasses what we will do inside the data centre and what will work for the coherent market,” says Brad Booth, chair of COBO and principal network architect for Microsoft’s Azure Infrastructure.

COBO was established in 2015 to create an embedded optics multi-source agreement (MSA). On-board optics have long been available but until now these have been proprietary solutions. 

“Our goal [with COBO] was to get past that proprietary aspect,” says Booth. “That is its true value - it can be used for optical backplane or for optical interconnect and now designers will have a standard to build to.” 

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Stitching together disaggregated chips

The Optical Internetworking Forum (OIF) has begun work on a 112-gigabit electrical interface to connect chips in a multi-chip module.

The ultra-short-reach electrical interface for multi-chip modules adds to the OIF's ongoing CEI-112G project, started in August 2016, to develop a 112 gigabit-per-second (Gbps) serial electrical interface for next-generation optical modules. 

Source: Gazettabyte, OIF data. The year 2018 is an estimate.

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OIF starts work on a terabit-plus CFP8-ACO module

The Optical Internetworking Forum (OIF) has started a new analogue coherent optics (ACO) specification based on the CFP8 pluggable module.

The CFP8 is the latest is a series of optical modules specified by the CFP Multi-Source Agreement and will support the emerging 400 Gigabit Ethernet standard.

Karl GassAn ACO module used for optical transport integrates the optics and driver electronics while the accompanying coherent DSP-ASIC residing on the line card.

Systems vendors can thus use their own DSP-ASIC, or a merchant one if they don’t have an in-house design, while choosing the coherent optics from various module makers. The optics and the DSP-ASIC communicate via a high-speed electrical connector on the line card.

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OIF document aims to spur line-side innovation

The Optical Internetworking Forum (OIF) has completed defining the CFP2-ACO (analogue coherent optics) module, used for coherent-based optical transmission. The industry body's CFP2-ACO Implementation Agreement document has been developed to help optical component vendors bring innovative line-side products to market more quickly.

The CFP2-ACO. Source: OIF

The pluggable CFP2-ACO houses the coherent optics, known as the analogue front end. The components include the tuneable lasers, modulation, coherent receiver, and the associated electronics - the drivers and the trans-impedance amplifier. The Implementation Agreement also includes the CFP2-ACO's high-speed electrical interface connecting the optics to the coherent DSP chip that sits on the line card.

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OIF moves to raise coherent transmission baud rate

The Optical Internetworking Forum (OIF) has started modulator and receiver specification work to enhance coherent optical transmission performance. The OIF initiative aims to optimise modulator and receiver photonics operating at a higher baud rate than the current 32 Gigabaud (Gbaud).

"We want the two projects to look at those trade-offs and look at how we could build the particular components that could support higher individual channel rates,” says Karl Gass of Qorvo and the OIF physical and link layer working group vice chair, optical.  

Karl Gass

The OIF members, which include operators, internet content providers, equipment makers, and optical component and chip players, want components that work over a wide bandwidth, says Gass. This will allow the modulator and receiver to be optimised for the new higher baud rate.

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OIF shows 56G electrical interfaces & CFP2-ACO

The Optical Internetworking Forum (OIF) is using the OFC exhibition taking place in Los Angeles this week to showcase the first electrical interfaces running at 56 Gigabit. Coherent optics in a CFP2 pluggable module is also being demonstrated.

“The most important thing for everyone is power consumption on the line card”

The OIF - an industry organisation comprising communications service providers, internet content providers, system vendors and component companies - is developing the next common electrical interface (CEI) specifications, as well as continuing to advance fixed and pluggable optical module specifications for coherent transmission including the pluggable CFP2.

“These are major milestones that the [demonstration] efforts are even taking place,” says Nathan Tracy, technologist at TE Connectivity and the OIF technical committee chair.

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OIF demonstrates its 25 Gig interfaces are ready for use

Eleven companies have been participating in nine demonstrations at the European Conference and Exhibition on Optical Communication (ECOC2013) being held in London this week.

The Open Internetworking Forum (OIF) has demonstrated its specified 25 and 28 Gigabit-per-second (Gbps) electrical interfaces working across various vendors' 100 Gigabit modules and ICs.

"The infrastructure over the backplane is maturing to the point of 25 Gig; you don't need special optical backplanes" John Monson, Mosys

"The ecosystem is maturing," says John Monson, vice president of marketing at Mosys, one of the 11 firms participating in the demonstrations. "The demos are not just showing the electrical OIF interfaces but their functioning between multiple vendors, with optical standards running across them at 100 Gig."

The demonstrations - using the CFP2, QSFP and CPAK optical modules and the 28Gbps CEI-28G-VSR module-to-chip electrical interface - set the stage for higher density 400 and 800 Gigabit line cards, says Monson. The CEI-28G-VSR is specified for up to 10dB of signal loss, equating to some 4 to 6 inches of trace on a high-quality material printed circuit board.

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