OIF approves CEI Rev. 3.1, starts new work on 56-Gbps interfaces

Members of the Optical Internetworking Forum (OIF) have approved revision 3.1 of the Common Electrical Interface (CEI) implementation agreement (IA) document, which specifies the electrical characteristics of transmitters, receivers, and channels for interface speeds up to 28 Gbps. The group also launched new work on 56-Gbps technology for 100-Gbps and 400-Gbps applications.

The new CEI revisions include two new clauses defining additional CEI-28G interfaces that are already being implemented. CEI-28G-VSR specifies a chip-to-module electrical interface for use in the range 19.6 Gsym/s to 28.1 Gsym/s, with up to 10 dB of loss and a single connector. This clause defines the characteristics required to communicate between an optical module and a host chip and meet interoperability requirements at the module connector. CEI-28G-VSR has been implemented for several optical module products, the OIF points out

CEI-28G-MR defines requirements for a chip-to-chip medium-reach high-speed electrical interface between nominal baud rates of 19.90 Gsym/s and 28.1 Gsym/s with 20 dB of loss. The new specifications address the need for medium reach, shorter length backplane channels with lower loss. Transmitters and receivers optimized to meet CEI-28G-MR and used in medium reach applications will offer power advantages over components designed for higher loss backplanes, the OIF points out.

The CEI-28G-MR signals the completion of the 28G IAs. “The OIF has focused on keeping the CEI IA up-to-date and forward looking,” said David Stauffer, of Kandou and the OIF Physical and Link Layer working group chair and board member. “These new interface definitions are important as the industry is currently deploying 100G applications and needs to continually support faster and more cost-effective electrical interfaces to optical components.”

Meanwhile, the OIF also is looking into electrical 56-Gbps specifications for higher-density 100- and 400-Gbps systems. The group plans to focus on specifications for both chip-to-module and chip-to-chip applications. A new project in this area launched during the Q1 meeting will address medium-reach applications; it complements ongoing work for 56-Gbps short-reach interface applications.

At the Q1 quarterly meeting the OIF conducted a 56G workshop to gather input on requirements for electrical link technology for 400G applications. The workshop provided a forum for input on where 56G is heading and how to address the next generation applications. The OIF says it will continue to seek industry input as necessary to help enable the success of 400G standards.

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